STATE OF FLORIDA
STATE BOARD OF CONSERVATION
DIVISION OF GEOLOGY
FLORIDA GEOLOGICAL SURVEY Robert 0. Vernon, Director
REPORT OF INVESTIGATIONS NO. 44
GROUND-WATER RESOURCES
OF POLK COUNTY
By
Herbert G. Stewart, Jr.
Prepared by the
UNITED STATES GEOLOGICAL SURVEY
in cooperation with the DIVISION OF GEOLOGY the
130ARD OF COUNTY COMMISSIONERS OF POLK COUNTY and the
SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT 1966
FLORIDA STATE BOARD
OF
CONSERVATION
HAYDON BURNS
Governor
TOM ADAMS
Secretary of State
BROWARD WILLIAMS
Treasurer
FLOYD T. CHRISTIAN
Superintendent of Public Instruction
EARL FAIRCLOTH
Attorney General
FRED O. DICKINSON Comptroller
DOYLE CONNER
Commissioner of Agriculture
W. RANDOLPH HODGES
Director
Lkarjlk OF TRANSMITTAL
J�4or~Id geoogi cal &Srve
August 16, 1966
Honorable Haydon Burns, Cluaivmn Florida State Board of Conservation Tallahassee, Florida
Dear Governor Burns:
The Division of Geology of the State Board of Conservation is publishing, as Report of Investigations No. 44, a detailed geologic and hydrologic study, covering the "Ground Water Resources of Polk County." This report was prepared by Mr.- Herbert G. Stewart, Jr., geologist with the U. S. Geological Survey, in cooperation with the Board of Conservation, the Board of County Commissioners of Polk County, and the Southwest Florida Water Management District.
The detailing of the geology and hydrology of Polk County provides the necessary data on many of Florida's *phosphate deposits, o!1 a large part of the Green Swamp water management area, and will contribute toward the further development of this area.
Respectfully submitted,
Robert 0. Vernon, Director
Divison of Geology
Completed Manuscript received
August 16, 1966
Published for the Florida Geological Survey
By Rose Printing Company
Tallahassee 1966
CONTENTS
Page
Abstract 1
introduction 2
Purpose and scope of investigation 2
Previous investigations 3
Methods of investigation 4
Well-numbering system 6
Acknowledgements 7
Geography 7
Location 7
Topography 9
Climate 1i
Transportation 12
Agriculture 13
Mineral resources 13
Industry 14
Geology 14
Stratigraphy 14
Eocene Series 20
Oldsmar Limestone 20
Lake City Limestone 28
Avon Park Limestone 80
Ocala Group 33
Inglis Formation 33
Williston Formation 35
Crystal River Formation 35
Oligocene Series 38
Suwannee Limestone 38
Miocene Series 39
Tampa Formation 40
Hawthorn Formation 45
Undifferentiated clastic deposits ---------46
Phosphate deposits 47
Coarse clastic deposits 47
Structure 48
History of structural movements 51
Solution features 52
Cavities 62
Sinkholes 65
Hydrology 69
Surface water 70
Streams 70
Lakes 72
Evapotranspiration 76
Ground water 77
Occurrence
Nonartesian aquifer 78
Characteristics 78
Water-level fluctuations 79
CONTENTS Pag,2
Uppermost artesian aquifer ------------Secondary artesian aquifer 83
Characteristics ------------- 83
The piezometric surface 85
Areas of artesian flow ------ 88
Water-level fluctuations 89
Floridan aquifer 89
Characteristics . 89
The piezometric surface . ---- 91
Areas of artesian flow -------- 100
Water-level fluctuations 100
Water-level history . 102
Hydraulics ------------ 105
Specific capacity of wells --------------- . 105
Vertical movement of water 112
Pumping tests ------------- 112
Hydrologic properties of selected limestone core samples 115
Recharge ------------- 116
Nonartesian aquifer ------- ------------- 116
Uppermost artesian aquifer ----------------- 117
Limestone aquifers ---------------_- ----------- 117
Secondary artesian aquifer . ___ . 120
Floridan aquifer _. . ____ . -------- 121
Quality of water _. ----------- ---------------- -------------- 129
Chemical constituents -------_------ _ . 129
Change of chemical quality with time 133
Change in chemical quality with depth -------_-------- 133
W ater temperature -------_-------------------_ ---- 134
Summary of chemical quality __. . ------ ---------- 135
W ater use -------------- - ------ - 136
Public supply -------- 136
Domestic supply --------------------------- 138
Industrial supply ---_-------------- 138
Irrigation supply .- ------- ------------- 139
Miscellaneous supplies ---------------_-- 140
Summary of water use -------------- 141
Special problems ------ -_._-.__ . 141.
Lake Parker 141
History and nature of problem 141
Water budget . 147
Conclusions 151
Scott Lake 153
History and nature of the problem 153
Water budget 158
Conclusions 161
Summary . ---- 161
References 165
ILLUSTRATIONS
Fiigure Page
1 Map of Florida showing the location of Polk County and the wellnumbering system ------ 6
2 Topographic map showing major physiographic features --- 8
3 Graph showing total annual rainfall at Lakeland, 1915-59 ------ 11 4 Map showing the location of selected wells --------- Facing page 14 5 Geologic map of the pre-Miocene formations 34
6 Geologic sections along lines A-A' and B-B'. Sections located on
Figure 5 43
7 Geologic sections along lines C-C' and D-D'. Sections located on
Figure 5 ---------- 44
8 Structure-contour map on top of the Inglis Formation 50
9 Map showing the location of wells penetrating solution features in
the limestones 63
10 Map showing location of recent sinkhole collapses 66
11 Photographs of recent sinkhole collapses _.-------. --------- 68
12 Hydrographs of water levels in Lakes Wire, Hollingsworth, Deeson,
Crystal, and Bonny near Lakeland and rainfall at Lakeland,
1954-59 74
13 Water-table contour of the Lake Parker area, June 25-30, 1956 ----- 80
14 Map showing water levels in selected wells penetrating the nonartesian aquifer, (October 29, 1959 to February 4, 1960) . _81
15 Hydrograph showing fluctuations of the water table in a well near
Haines City (810-136-2) in the nonartesian aquifer -- 82
16 Hydrographs showing fluctuations of the piezometric surface in a
well near Lakeland (803-153-18) and a well near Frostproof (744131-1) in the secondary artesian aquifer --- 85
17 Piezometric-contour map of the secondary artesian aquifer of Lake
Parker area (June 1956) 86
18 Piezometric-contour map of the secondary artesian aquifer in Lake
Parker area (October 1959 to February 1960) 87
19 Piezometric-contour map of the secondary artesian aquifer (October 1959 to February 1960) 88
20 Piezometric-contour map of the Floridan aquifer (October 1959 to
February 1960) Facing page 90
21 Piezometric-contour map of the Floridan aquifer in northwest Polk
County (June 1956) 98
22 Piezometric-contour map of the Floridan aquifer in Lake Parker
area (October 1959 to February 1960) 99
23 Hydrographs of fluctuations of piezometric surface in a well near
Lakeland (759-158-1) and a well near Davenport (810-136-1) in
the Floridan aquifer 101
24 Map of peninsular Florida showing the piezometric surface of the
Floridan aquifer in 1944 123
25 Piezometric-contour map of the Floridan aquifer at Lakeland (November 20, 1959) 128
26 Map showing hardness of water in selected wells in the Floridan
aquifer .---------- 132
27 Map showing water temperatures in selected wells in the Floridan aquifer 14
28 Graph showing total annual municipal pumpage by City of Lakeland, 1928-59 1317
29 Log of sediments penetrated in test hole 805-156-A, in Lake Parker. 144 30 Hydographs of water levels in Lake Parker and in wells 803154-10 and 806-154-1, 1954-56 145
31 Hydrographs of water levels in Lake Parker and in wells 805-155-1, 2, and 3, 1956-59-------------------------------146
32 Hydrographs of water levels in Lake Parker and in wells 805155-1, 2, and 3, during 1958 147
33 Hydrographs of water levels in Scott Lake and in wells 758-156-5, 757-155-3, and 757-155-6, 1954-60------------------154
34 Hydrographs of water levels in wells in the nonartesian aquifer in the Scott Lake area 155
35 Map showing water levels and other features of the Scott Lake area, July 1956 156
36 Map showing water levels and other features of the Scott Lake area, October 1959-February 1960 157
TABLES
Table
1 Mean monthly temperature and rainfall at Lakeland, Florida for
period 1915 to 1959 12
2 Total annual rainfall at U.S. Weather Bureau stations in Polk
County, 1954-59 12
3 Geologic data from wells in Polk County -16
4 Solutional features penetrated by wells in Polk County 54
5 Records of the occurrence of recent sinkholes in Polk County------.67 6 Annual runoff by drainage basins, 1954-59 71
7 Water levels observed during drilling operations---------------------- 92
8 Net change in water levels in wells in the Floridan aquifer, 1934-59 103 9 Specific capacities of selected wells in Polk County 104
10 Specific capacities of wells in Polk County .106
11 Hydrologic properties of limestone core samples f rom well 805154-8-----.------- -------------------_------- -113
12 Range of concentration of chemical constituents in waters of Polk
County 100
13 Annual metered punipage by municipal systems in Polk County,
1954-59-------------------------126
14 Stream-flow measurements in the vicinity of Lake Parker and Saddle Creek 148
GROUND-WATER RESOURCES OF
POLK COUNTY, FLORIDA
By
Herbert G. Stewart, Jr.
ABSTRACT
Polk County, Florida is located approximately in the center of the Florida peninsula, and is an area which requires large quantities of water for industry, agriculture, and municipalities. Nearly all water supplies in the county are obtained from ground-water sources. Domestic and small irrigation supplies are obtained from limestones of the Hawthorn Formation of Miocene age, and to a lesser degree from unconsolidated plastic deposits which range in age from middle Miocene to Recent. Large water supplies are obtained from the Floridan aquifer which includes limestones ranging in age from middle Eocene to middle Miocene. Geologic studies near Lakeland show that the Avon Park Limestone is the lowest unit of the Floridan aquifer, and that there has been no circulation of ground water in the underlying formations.
The southern end of the Ocala uplift extends into Polk County and the highest piezometric levels in the Floridan aquifer occur in the county. As a result of the Ocala uplift the rocks of the Floridan aquifer have been highly fractured which has resulted in solutional. development of the limestone and extensive cavern systems. The fracturing has also permitted the free circulation of water between all units of the aquifer.
Water recharges the Floridan aquifer principally by downward percolation from surficial sands and through the intervening Units to the Floridan aquifer. Only a few inches of rainfall per year enters the aquifer as recharge in the county. Water budget analysess for two lakes near Lakeland, during the first 6 months Of 1956, show that the lakes recharged the underlying limestone ;iquifers. Lake Parker recharged water to the Floridan aquifer at .1. rate of about 2.5 inches per month and Scott Lake recharged water to the limestones of the Hawthorn Formation at a rate of About 5 inches per month. Data suggest that other lakes in the
-ounty may also recharge the aquifers at slow rates.
During 1959, approximately 80 billion gallons of ground water ,vere pumped from the aquifers in the county. During the same ,7ear approximately 120 billion gallons were determined to re-
FLORIDA GEOLOGICAL SURVEY
charge the limestone aquifers within the county. The excess o_,' about 40 billion gallons moves through the aquifers into adjacen-*, counties. The potential availability of ground water in the county can be increased by using more ground water which in turn creates increased storage in the aquifers.
INTRODUCTION
PURPOSE AND SCOPE OF INVESTIGATION
The investigation upon which this report is based was begun in April 1954 by the U.S. Geological Survey in cooperation with the Florida Geological Survey and the Board of County Commissioners of Polk County. Preparation of the final phases of the manuscript was effected with the cooperation of the Southwest Florida Water Management District. The general purpose of the investigation was to provide basic information to assist in the intelligent development of the water resources of Polk County. The investigation was specifically designed to (1) determine the relationships between some of the lakes in the county and the ground-water aquifers, including the effects of large withdrawals of ground water on lake levels; (2) determine the mechanics and quantities of recharge to the principal ground-water aquifers and to locate areas in which such recharge is occurring; and (3) determine amounts of water being used and to estimate the total iIMOUnt available from the principal aquifers.
This report presents general information on the geology and hydrology of the county and specific information on two lake basins located in the northwestern part of the county. The relationship of the many lakes in this area to the ground-water supply and the effects of large withdrawals of ground water on both ground-water and surface-water levels are matters of great interest in the county. The complexity of the hydrology of the ares made it necessary to study the geology in considerable detail.
A preliminary report of the investigation was prepared by the author (1959) and presented detailed information on specific problems relative to two lakes near Lakeland.
This report constitutes the final interpretative report of the investigation. A companion report of basic data was also prepared (Stewart, 1963) and contains well data, chemical analyses, water-
REPORT OF INVESTIGATION No. 44
Ievel measurements and lake-stage measurements, and other data I;'athered during the course of the investigation.
PREVIOUS INVESTIGATIONS
Some geologic and hydrologic work has been done in Polk County as part of regional or statewide investigations. Most of this work has been done by the U.S. Geological Survey and the Florida Geological Survey.
Cooke (1945), Vernon (1951), and Parker, Ferguson, Love, and others (1955) described the general geology of central Florida and made many references to Polk County. Cole (1941, 1945), Mansfield (1942), Cathcart and Davidson (1952), Davidson (1952a, 1952b), Cathcart and others (1953), Carr and Alverson (1953, 1959), Puri (1953b, 1957), Bergendahl (1956), Cathcart and McGreevy (1959), Ketner and McGreevy (1959), Altschuler, Clark, and Young (1958), and Altschuler and Young (1960) discussed the geology of one or more of the formations which are present in the county. Fenneman (1938), Cooke (1939), MacNeil (1950), and White (1958) discussed the topographic features of central Florida, and their origin and development.
Sellards (1908), Sellards and Gunter (1913, p. 262-264), Matson and Sanford (1913, p. 388-390), and Gunter and Ponton (1931) prepared early discussions and data concerning ground water in Polk and other counties of central Florida. Stringfield (1935, 1936, p. 148, 172-173, 186) investigated ground water in the Florida peninsula and presented data from Polk County. An important result of his investigation was a piezometric map of the principal artesian aquifer of peninsular Florida (the Floridan aquifer in this report) which shows areas of recharge to and discharge from the aquifer in Polk County. The map was expanded to include most of northwestern Florida and part of southern Ceorgia by the work of M. A. Warren, V. T. Stringfield, and 1. Westendick', and was shown by Cooper (1944, fig. 2), Warren (1944, fig. 3), and Unklesbay (1944, fig. 5). Cooper (1944), tringfield and Cooper (1951a), and Cooper, Kenner, and Brown (1953) discussed the ground water of Florida and referred to ret arge of the principal artesian aquifer in Polk County. Papers by 3'erguson, Lingham, Love, and Vernon (1947), and Stringfield ,nd Cooper (1951b) described the geologic and hydrologic fea'Oral communication, H. H. Cooper, Jr., U.S. Geological Survey, May 4,
FLOREDA GEOLOGICAL SURVEY
tures of springs in Florida and presented flow measurements and other data for some springs. Peek (1951) discussed the cessation of flow of Kissengen Spring in Polk County.
Collins and Howard (1928), Black and Brown (1951), and Wander and Reitz (1951) discussed the chemical quality of ground and surface water in Polk County and other parts of Florida, and presented many analyses.
METHODS OF INVESTIGATION
Field work began May 1, 1954 with an inventory of water supplies in the northwestern part of the county. Later the inventory was extended to include the remainder of the county. Information on the depth, depth and diameter of casing, water level, yield, type of pump, use, and quality of the water was obtained for more than 1,300 wells.
During the inventory, specific wells were selected for the observation of water-level fluctuations. Water levels were measured periodically in most of the observation wells, however, continuous water-level recording instruments were installed on 13 of them. The levels of several lakes in the northwestern part of the county also were measured periodically and recording gages were installed on Lake Parker and Scott Lake, in the Lakeland area.
Current-meter and temperature logs were obtained from 12 wells in the county.
Samples of water were collected from wells and surface sources for chemical analysis. Composite water samples were collected from wells being pumped. Water samples were also collected from bailers, both during drilling operations and after completion of wells.
Consolidated rocks were found exposed at land surface in small areas of extreme northwestern Polk and adjacent counties. These out-crops were examined, mapped, and samples collected in reconnaissance with Mr. E. W. Bishop, Florida Geological Survey. During mining operations the phosphatic limestones of the Hawthorn Formation were briefly exposed in the bottoms of some of tho mine pits in the Lakeland area, and these were studied and described whenever possible. Unconsolidated deposits, below the' loose surficial sands, were found exposed in road-cuts, borrow-pi in the ridge areas along the newer highways, and 'in phosphate mine pits and these deposits were briefly studied and described.
Studies of rock cuttings were made during well-drilling opera-
REPORT OF INVESTIGATION No. 44
ti ins. Samples from about 250 wells in Polk County are presently filed at the Florida Geological Survey, most of which were colIe.-ted and donated by the local well drillers. Cuttings from 25 deep wells, 14 shallow wells, and 4 test holes were collected and examined during the investigation. Eleven other sets of samples from wells in the county were collected and logged by other geologists of the State and Federal Surveys. Most of these wells were drilled by the cable-tool method. A few wells were started and the casing installed by the rotary method, and the open-hole portions of the wells completed and samples collected by the cable-tool method.
Two deep exploratory wells drilled near Lakeland by private industry during 1959-60 made an important contribution to geologic and hydrologic knowledge in this county. The first well, 805-154-8, five miles northeast of Lakeland, was continuously cored from 58 feet below land surface to a total depth of 1,479 feet with more than 95 percent core recovery. The second, 801-2003, three miles southwest of Lakeland, was cored from near the top of the thick dolomite interval of the Avon Park Limestone (652 feet below land surface) to a total depth of 1,846 feet. The formations penetrated by the wells include formations deeper than those normally penetrated by water wells in the county.
The cores from these two wells provide the most complete and accurate record obtainable from Polk County of the rock formations penetrated and together with the electric and gamma-ray logs from the two wells, are used as basic control for all geologic studies in this report. Rock cuttings and electric logs from other wells studied during this investigation are u sed as second-order control; other sets of well samples and electric logs in the files of the Florida Geological Survey are used as third-order control; electric logs of wells from which no samples are available are used as fourth-order control.
Additional geologic information was obtained from 65 electric lofs of wells made with a single-electrode logger and from 61 ga)mma-ray logs. For geologic correlation 29 electric logs and 30 g,-mma-ray logs were made in wells from which rock cuttings w ~re available for study. The electric logs served as the basis for r', ich of the interpretation of geologic structure in this report. The g,' mma-ray logs were less useful as a geologic tool, but served as an ai xillary source of data with reference to pebble-phosphate deP: sits and the Miocene limestones. -Drillers and well owners have & 0o given to the State or Federal Geological Surveys 146 descrip-
6 FLORIDA GEOLOGICAL SURVEY
tive logs of wells from which cuttings were not collected. These descriptive logs have been of value in the interpretation of groundwater conditions, general lithology, and geologic structure.
WELL-NUMBERING SYSTEM
The well-numbering system used in this report is based on latitude and longitude coordinates. Figure 1 shows the wellnumbering system used in this investigation. The well number was assigned by first locating each well on a map that is divided into 1-minute quadrangles of latitude and longitude, then numbering each well in a quadrangle in the order of inventory. The well number is a composite of three numbers separated by hyphens: The first number is composed of the last digit of the degree and the
ge t IO llgd l .*lI Of the G,rlnwC. ECQIlo, p,Orl rnla.,on
. .G E R IG I A
4 "C"IA,'E. .
. O '
on,
3 0o SO o3o
ar3 .11 :Olii i3 O
I l iiIilll
W :.::"! t I. 'I
f t e.' mCo o f r- " , . . .g. .A
. 28I2 3
|All a 2 - 1i. 28 Cit
4 ,.r II m Wlodaoo t .l of m OoIlh 2 8 , cf
Figure 1. Map of Florida showing the location of Polk County and the well-numbering system.
REPORT OF INVESTIGATION No. 44
ti -o digits of the minute of the line of latitude on the south side of a 1-minute quadrangle; the second number is composed of the last digit of the degree and the two digits of the minute of the line of longitude on the east side of a 1-minute quadrangle; and the third number gives the order in which the well was inventoried in the quadrangle. For example, well 826-131-3 is the third well inventoried in the 1-minute quadrangle north of 28*261 north latitude and west of 81'311 west longitude. By means of this system, wells referred to by number in the text can be located on the various plates and illustrations of this report.
The same system is used in numbering test holes, exposed sections, sampling stations, and points of various observations that were collected or described, except that consecutive letters of the alphabet are used instead of consecutive numbers. For example, 805-156-A was a test hole. The test holes were filled and abandoned immediately after drilling, and therefore are distinguished from wells.
ACKNOWLEDGMENTS
The investigation was greatly facilitated by the interest, cooperation, and assistance of city, county, and industrial officials., residents, and landowners. Well drillers in the area have repeatedly made their time, experience, and records available to the author. Appreciation is here expressed to all of these people.
Grateful acknowledgment is here made to-E. W. Bishop, geologist, Florida Geological Survey, and F. W. Meyer, geophysicist, U.S. Geological Survey, for the many beneficial discussions and the exchange of ideas and concepts during the investigation.
GEOGRAPHY
LOCATION
Polk County comprises an area of about 1,860 square miles in t! e central part of peninsular Florida. (See figure 2.) The county w'.is established February 8, 1861, by separation from what was t! en Hillsborough County. Hetherington (1928, p. 14) records an a count of Mr. B. F. Blount that indicates that the population in C Aober 1851, of what is now Polk County, totaled about 20 fami-
8 FLORIDA GEOLOGICAL SURVEY
t WPL ANAY ON
'A L'.
.~
timethe opuatio hasinceae st'aily
The following population figure frtecutywr ae
fro pulse eotso5h .Bueuo ess
1890N 7 \0
1900 12,472O
1902,4
Tm he population has iocnraed teadily.an onsaon Thegefolloweingepopulationefigures.forvthelcuntye weure taken fro publisrhedn rprts of the u.S. Bn urea of Cesus: eas
the ~ ~ ~ 19 LaeWls7,905spreypouae.Th oter atC the ~ ~ ~ 10 12,472as pasl opltd Gnrlyteeara r
REPORT OP INVESTIGATION No. 44
poorly-drained grasslands and flatwoods, relatively low and flat, wid are largely devoted to cattle ranching. During the period of this investigation many isolated, well-drained hills and low ridges within the northern and southern areas were cleared and citrus trees were planted.
The three major ridges and much of the well-drained interridge areas are devoted to citrus groves. Numerous small truckfarms are also found in the inter-ridge areas. Vast areas in the southwestern part of the county have been mined for pebblephosphate. Much of the mined-out area has not been improved and now stands as rugged spoil piles.
TOPOGRAPHY
Polk County is part of the Central Highlands physiographic division of Cooke (1939, p. 14, fig. 3), the Limesink and Lake Regions of the Floridan Section of the Atlantic Coastal Plain province of Fenneman (1938, p. 46-65, and the Atlantic Coastal Plainground-water province of Meinzer (1923a, p. 309-314).
The county is part of the highland area that trends along the longitudinal axis of the Florida peninsula. The major topographic features of the county are three long, irregular, north-south trending ridges which are separated and bounded by relatively flat lowland. These and other topographic features are shown in figure 2. The easternmost of the ridges extends from the common corner of Polk, Osceola, Orange, and Lake Counties approximately south through Haines City, Lake Wales, and Frostproof, and into the southern part of Highlands County. MacNeil (1950, p. 101) has referred to the eastern ridge as the Lake Wales ridge, and White (1958, p. 10) also uses this name. This is the highest, longest, and narrowest of the three ridges in the county. Altitudes on the crest of the ridge range from 150 to 305 feet above msl (mean sea level) and are highest at Lake Wales and Babson Park.
The central, or Winter Haven ridge (White, op. cit.), begins al)ruptly at Polk City, and continues south-southeastward through Auburndale and along the east side of the Peace River valley to F',. Meade. It appears to merge with the Lake Wales ridge about 4 miles southwest of Frostproof. This ridge is actually a zone of siiall ridge-remnants approximately 8 miles wide. Between Bart(w and Ft. Meade this ridge becomes a much more massive unit, V oader and higher than the northern unit. Altitudes along the c) ast of the northern unit range from 150 to 200 feet ms], and
FLORIDA GEOLOGICAL SURVEY
much of the southern unit ranges from 200 to 230 feet msl.
The westernmost ridge, or the Lakeland ridge (White, 19.58, op. cit.), begins abruptly about 10 miles northwest of Lakeland and extends south-southeastward through Lakeland and betweeii Bartow and Mulberry, to the vicinity of Ft. Meade. Altitudes along the crest of the ridge range from 150 to 270 feet msl, and muchl of it lies above 200 feet msl. The Lakeland ridge is more continu-. o us and narrow than the Winter Haven ridge. The Lakeland and] Winter Haven ridges appear to trend slightly more north-west. southeast than the Lake Wales ridge.
All of the ridges aire being lowered and dissected by sinkholes. The Lake Wales ridge has been transected by sinks in the Frostproof area, and many other saddles in the ridge are approaching complete transection.
The northern part of the Winter Haven ridge has been thoroughly dissected by sinks. However, the massive southern unit retains a relatively juvenile linearity on the western flank, and is being slowly dissected on the lower parts of the eastern flank. Transection of the two units of this ridge has been complete in a broad area along Florida Highway 60, north of Alturas. The Lakeland ridge is being dissected much more slowly than the other two, though large non-lake sinks appear to be more numerous in this ridge than in the others.
The northern part of the county, west of the Lake Wales ridge and north of the other two ridges, is a broad poorly-drained flatland that slopes northwestward from about 140 feet msl to about 90 feet msl. It is an area of pine flatwoods, cypress swamps (called domes), and intervening grasslands.
On the eastern flank of the Lake Wales ridge there are two large areas of dune-covered terraces and sand hills, one located southeast of the city of Lake Wales and another north of Davenport. East of these is the broad, slightly rolling to flat, marshy lowland of the Kissimmee River.
Another broad, flat to rolling, lowland exists across the soulhern part of the county, west of the Lake Wales ridge and south of the other ridges. Much of this area is poorly-drained pine fiatwoods. The interridge areas are partly rolling lower land, a~i partly low flatwoods and marshes.
Maximum local topographic relief in the county is 219 feet in the Lake Lenore basin, southeast of Babson Park. 'Total relief in the county is 255 feet (from 50 to 305 feet mnsl).
Surface drainage is poorly developed in the county. On the &lit-
REPORT OF INVESTIGATION No. 44
hinads there are hundreds of perennial and ephemeral swamps and b~zsins of interior drainage. In the ridge areas, basins of interior drainage are even greater in number, depth, and diameter than on the lower flatlands. In both types of topography some of the basins of interior drainage (sinkholes) contain lakes.
CLIMATE
All climatic data used in this report are taken from the published records of the U.S. Weather Bureau. The data from the Lakeland station aire believed to be generally representative of the county.
The area has a humid subtropical climate and only two pronounced seasons-winter and summer. The average annual temperature is 720F, and the average monthly temperatures range from 621F in December and January to 821F in August. The average annual rainfall is 51.43 inches, about three-fifths of which occurs from June through September. Most of the rainfall comes from thunderstorms, which average about a hundred per year. Total annual rainfall at Lakeland, for the period of record, is shown graphically in figure 3. The mean monthly temperature and rainfall through 1959 are s-hown in table 1.
Total annual rainfall at the Weather Bureau stations in the county during the period of this investigation is given in table 2.
8~o
70
7 AVERAGE 7
//7 77
/X/
40
Figure 3. Graph showing total annual rainfall at Lakeland, 1915-59.
FLORIDA GEOLOGICAL SURVEY
It is to be noted that the rainfall at Lakeland, Bartow, and Lake Alfred Experiment Stations in 1959 established record highs for these stations. The Mountain Lake station lacked 31/2 inches that year of equaling its record high. The second lowest rainfall of rec. ord for Lakeland (36.30 inches) occurred in 1954, and the lowest rainfall of record at Lake Alfred in 1955. Table 2 clearly indicates the great difference in local precipitation in this'area. The difference between highest and lowest total annual rainfall for the stations shown exceeded 20 inches in 1957 and 1958.
TABLE 1. Mean monthly temperature and rainfall at Lakeland, Florida', for period 1915 to 1959.
Ier(prturo Rainfall
Month (0F) (inches)
January 62.4 2.21
February 63.9 2.47
March 67.3 3.69
April 72.0 3.24
May 77.0 4.43
June 80.4 7.38
July 81.6 8.02
August 82.0 7.30
September 80.3 6.42
October 74.7 2.88
November 67.2 1.72
I)ecember 63.0 1.97
Annual 72.7 51.79
1 U.S. Weather Bureau. Local Clinatological Data with comparative data,
L.akeland, Florida for period 1915 to 1959.
TABLE 2. Total annual rainfall at U.S. Weather Bureau stations in Polk County, 1954-59.
Mean
Station 195.1 1955 1956 1057 1958 1959 annual
Bartow 51.19 41.41 40.34 . 73.72 61.82 83.44 "54.12
Lake Alfred Exper. Sta. 38.27 35.66 44.40 57.99 49.89 o76.57 51.47
Lakelaad 36.30 44.08 45.12 62.38 41.74 70.24 51.43
Mountain Lake (at Lake Wales) 46.05 43.98 41.35 58.21 55.09 71.42 52.70 Winter ILfv,.n 38.68 38.78 44.65 66.07 52.73 73.28 1
Babson Prk - - 36.54 51.14 57.50 66.97 2
1 U.S. Weather Bureau "Climatological Data-Florida-Annual Summary' 1954 through 1959
s Not computed-less than 20 year record available
a From U.S. Weather Bureau long-term records
e estimated
TRANSPORTATION
The principal highways in the county are U.S. Highways 93, 27, and 17, which are north-south routes, and U.S. Highway 92 and Florida Highway 60, which are east-west routes. These aie
REPORT- OF INVESTIGATION No. 44
augmented by a network of additional state and county roads. However, in the less populated northern and eastern parts of the county there are only a few graded roads.
Most of the towns and cities of the county are served by main Iiiies of the Seaboard Air Line or Atlantic Coast Line Railroads.
In general, the area is poorly served by direct air service; only Lakeland has regularly scheduled flights.
AGRICULTURE
Various types of agriculture play an important part in the economy of the area, and many are important water users. The most important type of agriculture is the growing of citrus fruits, principally oranges and grapefruit. Cattle ranching is also an important part of agriculture. Truck-farming, lumber, and other agricultural pursuits are of less importance in the economy of the county.
In the 1954 Agricultural Census (U.S. Bur. Census, 1957, p. 149), Polk County ranked first in the State in the production of citrus fruits, having 8,012,894 orange, grapefruit, and lemon trees. The county is also a leader in the production of the less common citrus fruits, such as limes, tangeloes, and kumquats. Normally, the citrus groves are irrigated one or more times a year as required.
Locally the growing and marketing of truck-farm crops such as strawberries, peppers, beans, squash, and other vegetables is important. The truck farms are relatively small, and normally several different crops are grown in rotation during a single year. These crops are generally irrigated heavily 'and often.
In 1954 Polk County ranked first in the State in the production of cattle (U.S. Bur. Census, 1957, p. 107) with a total of 12.1,773 head. Ranches are usually large, and are located on the flatlands in the peripheral areas of the county.
MINERAL RESOURCES
At present eight companies are actively engaged in open-pit mining of pebble-phosphate in the county. Production in 1959 to7
taled 10.2 million long tons of phosphtae rock2 . The mining process utilizes large quantities of water; however, extensive storage, settlilg, and recirculation practices reduce the amount withdrawn
Personal communication, Mr. E. W. Bishop, Florida Geological Survey, November 7, 1960.
50' 45'
I I I
390C~12'
Lj
i
i;
~~i
"Yi j
rg f-o
I \ '-
i I I I I I I I
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3 miles--
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SCALE FOR INSETS
.2 ( I I
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. * ROCK ' i
r fRIDGE
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EXPLANATION
Ie Well
Number is identifcation number in I-minute quadrangle
I I.
DAVENPC 2#3 4 21
ES CITY
Ifr~I ~I
)- -.-5
*- J
1-. ,
r ,5O r4 -'*I
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0
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LAKE HAMILTC.N
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,* 2'
COUNTY
,,
.7 1 2~
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DUNDEE I'
, 2. 1._3 iW
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3 2
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6 PROOF
62.
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/ -I , 2-HIGHLAND o2 _T Y,
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8BABSON PAR
2; 1:2
MANATEE CO IF HARDEE
-~i ! 1 9 i i
86O 05
COUNTY
it1 1'
35'
8200'
H-IGH LANDS COUNTY
II I II I I I I I I I II
27*38' 10' 81007'
3ase compiled from L S. Geological
3 - ro tographic quadrangles.
O I 2 3 4. -5 6 miles
Figure 4. Map showing the location of selected wells.
82*8t' 05'
82"00'
' I
I II
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o G I
I
I 4 I I I I
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m
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(630)
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r 1 ! I l I J.1 2 1
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f II~. i. I -BT Y ~
3 I I I i, I ~ id L,,- I
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INSET A
192
r
i
i
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2 3
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/
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! RON', - -
a
FLORIDA GEOLOGICAL SURVEY
from ground-water aquifers.
More than ten companies were mining (dredging) silica sanJ from the unconsolidated deposits in the county in 1960. Five of these companies are located in the Lake Wales ridge, where the thickest deposits are found. Other companies were operating in or near Mulberry, Bartow, Ft. Meade, Waverly, and Winter Haven. Sand and gravel production totaled 3.3 million short tons in 1959 (U.S. Bur. Mines, 1959, table 5). Most of the water used in this production is readily obtained from the excavations, and does not represent significant industrial consumption of ground-water supplies.
Limestone has not been mined in the county due to the thickness of the unconsolidated overburden, low purity of the uppermost limestone in some areas, and high ground-water levels. However, a relatively large, previously unmapped area of silicified limestone, cropping out in the northwestern part of Polk County and southern parts of adjacent counties, which may become important to the economy of the county, is discussed later in this report. Silica replacement of the limestone surface and artesian ground-water conditions present problems in the newly mapped area, but an economic potential is clearly present. In 1960, agricultural limestone was being obtained from the Ocala-Brooksville area to the north or from western Manatee County to the southwest.
INDUSTRY
One of the major industries in the county is the packing, canning. and concentrating of citrus fruits and juices. Another, and less prominent, allied industry is the production of cattle feed from the peelings of citrus fruit. Juice concentrate plants are among the large consumers of ground water in* the county.
The refining of pebble-phosphate and the preparation of commercial fertilizers is a very large and important industry of the area. Polk County ranks first in the State in the production oC both the refined triple-super phosphate and fertilizers. These plants use very large quantities of ground water.
GEOLOGY
STRATIGRAPHY
A knowledge of the geology of the rock formations is essential in the evaluation of aquifers as sources of water. The texture an(
REPORT OF INVESTIGATioN No. 44
,,)mposition of the rocks affect the chemical composition of the ,-ater contained and the rate of ground-water movement through ttem. The thickness, areal extent, and fracturing of the various r ocks will also influence the rate of ground-water movement and yield of wells. Structural deformation and chemical alteration also AfTect the rate of movement through individual rock units and betwveen units.
Vernon (1951), Cooke (1945), and many others have described the rock units present in Polk County, their general relationships aind geologic history, the origin of the different unit names, and the criteria for their identification. However, there has been no previous work which describes the geology of the county in sufficient detail to understand the hydrology of the rock units.
The areal extent of the various units has not been previously established. The literature notes cavernous limestone in central Florida but does not detail the occurrence nor adequately consider the origin of these solution features which are so important to ground-water movement. The work of Vernon (1951, pl. 2) suggests the presence of extensive fracturing in the rocks of Polk County which would also greatly influence the hydrology. The existing literature does not define the thickness or depth of rocks which contain fresh water. Thus, a considerable part of this investigation was devoted to geologic studies that were aimed at providing more detailed information on hydrology.
All of the consolidated rocks of the county that are normally penetrated by water wells are limestones or dolomitized limestones. Over most of the county these are buried by phosphatic clays which are in turn covered by a blanket of sand that constitutes the surficial material. Consolidated rocks crop out in a few, relatively small, areas in the northern part of the county. Most of the geologic information for this report was obtained from rock cuttings taken from wells and by the interpretation of electric and gamma-ray logs of wells. Figure 4 shows the location of wells in Polk County.
Table 3 shows the depths to the tops of the various geologic ormations as determined during this investigation. Table 3 does ,lot include a summary of open-file geologic logs of wells by the 11iorida Geological Survey and which were used in the present tudy. In the following paragraphs the rock formations penetrated )Y wells in this county are discussed from oldest to youngest.
The stratigraphic nomenclature used in this report conforms c the usage of the Florida Geological Survey. It conforms also to
TABLE 8, Geologic data from wells in Polk County Approximate depth to top of each formation given in feet Data source: D, driller's log; G, gamma-ray log;
below land surface: a, absent; c, cased off; e, estimated. S, samples; X, electric log.
-, --v . r - - A
APPROXIMATE DEPTH TO TOP OF FORMATION
FOS IHawthorn Oeala Group
USG well Altitude Formation Avon
well number of land (limestone Tamps Suwannee Cr stal Park
number (W-) surface only) Formation Limestone River Williton [ails Limewtone Data ouroe Remarks
742 150-2 . 744-131-1
744-167-1 8852 745-14-1 536851
74&- 6853-1 2804 745- 568 .
745 * .9-2
7V7- 14-1 1726 7~7- 32-1 4963 747- 48-1 1062 747- 58-8
74T8 19-2 4288 7+9- 49-1 751-' 645 4185 752- 50-1 752- 50-2 8802 752- 50-4 2431 75' 28-1 4381
753-129-2
753-89-1 7538--3
754- 1-4
754" 55-2 155-' 51-83 75-134-2. 757-152-1 757-153-2
757-155757-1554 757-18&-7
758-144-1
7b9-144-2
4190
2742
1441 4255 4684
4902
98 98
148
e185
108
187 e160 eel6
202
115
180 100
120 173
e125 123 133 136
110
121 124
101
120 218 216
o109
264 117
128
265 266 258
140
e137
a
202 c219
140
50 o
112 185
250 090
58 e250 e52 @85 05, 125
80 220
130
92
a
040
120 85
29 250
cl50
140
60
210
a
282 o300 a?
230
a
250
a
a
e140 220
190
125
a?
124
C
0
64
250 250 72 293
a
a
200
a
a
703 0
71 ' 710 D . 8
*275
@394
a
320 c198 277
a
210 245 205
190
a
o236
120 300 300 80so 323
e55 150
290
155
140
380
447
285 370 354
310 385
210
140
258 250 248
435
0
203 250
425
250?
230
5007 027
495
590
474
405
300
309 370 382 368
545
541 324
565?
000 058
34b 540 632
487 500
350
333 395
407 392 610
582 330
590
- 330
630 D, 8 717 X
300 D., , X
010 D, X
X
D, 8
440 D. 8
444 G, X
49 X
450 G, X 605 D, 8
X
658 X 375 D, G, X
X
. .G X
G X
650b D, S
400 D, S
P-51
Tampa clay not renaeented
in samples; no driller's log
available.
Tampa not evident in samTampa not evident in samples or driller's log.
FGS Wgi-714 P-47
La intervals between samTampa clay not evident in samples or driller's los do.
- 4-- r~ _o _ -. Lot/U--- --4-- --- -a ~ r ~-
759-20-1 800-138-1
800-142-1 800-143-2
800-z46-1 80S0-5-1 800- 53-3 800-1 -3 800-54-6
800o 59-1 801 38-2 801-148.1 801" 54-5
801-8 54-
884 3200 724 4775
8420 4493
4253
801-2008- #2 core
802-139-2 5098
802-148-3 83307 802-144-2 5443
802-146-2 3851
802-149-4 80-15"-3
802-151-10 802-161-19
802-152-10 802-157-16
802-200-1 803-137-1 808-143-2
803-145-2 803-148-6 803-148-7 803-151-11 803-153-3
808-1534 803-153-24
3083
8422 4153 4737 1416 5353
2925
4050 4215 3772
8425
150
132 123
147 165
152
127 119
e124 e140 146
128 151
147 148
el35
120
145
el68
152
130 119
111 113 110 191 136
164 el38
155 133
141 113
128 127
124
0
cl51
104 cSO
140
90 75
c40 88 60
50 94 0
58 100
18
100
145
105
14.0
05
.34 40 60
24 081
a 155 140
72
80 80?
44 c055
c42 600
0
c75 118
132 190?
a
89
cOS 120 100 96
101
a?
c140 103
a
147 200
185
127 0110 186 130 106
128 1707
222 123
a
260 246
217
270?
83 129 214
i0 2907?
ISO ***
110 89 63
75
c15
90
a
76
82 688
a?
143 125
82 88
102
a
100
160 130 98 110 106 107
c18
314 '
8309 362
329 333
209
200
400 380
392
400?
e390
270
380 398
*** **-
243? 388
ei6i
240 200 230
i66 232
4287 325
444
310
G, X
A, 8, X G, S
S
8
G,X D, X G; r D, S
S'
D, S
e440 D, G, B, X
310
470 563?
, 8 D, 8 8S
D, S
x
S
D' S
DG x D, 8
'1VV --V A,1
from driller's log or sampies.
0-45
Contaiinated samr les.
Not chaaoteristio--my be
absent.
Very large ample interv!. ach formation top may be higher than shown. Tampa not evident in samples or
driller's log.
Los of circulation and collapse of hole prevented sampling and electric log: Lake City 1198 Oldsmar
1588.
Tampa clay not evident in
samples or driller's log. Ist sample 290 Tampa clay not evident in
samples; shown on driller's
log.
Large sample interval.
Large sample interval. Tampa clay not evident in
samples-no driller's log.
Tampa not clearly evident in samples, may be 10'.
TABLE 3 (Continued) a
APPROXIMATE DFPTIf TO TOP OF FORMATION. Fo8 Lrawthom Ocla Group
Us8G well Altitude Formation Avon
well number o land (lirestone Tamp. Suwrnae Cryst Park
number (W-) aurface only) Formation Limestone River Williston Inll Limestone Datasouree Remarks
88-353-28 3424
80-1-34 5444 136
S03-164-5 524 el41
80-1&6-11 3773 147
806-138-1 1733 131
804-138-2 5338 e133
614-143-1 4412 e133
804-151. . 129
804-152-2 3707 1S
804-153-4 3770 110
801-165-17 3764 148
830200-1 3838 157
805-I52 3841 131
805-154-8 11 core 130
X%- 55-2 'At- 554 xt5- 5-2 805- 57-16 M15- 59-1
-900- 37-2 806-JS-.]
006-40-1 8- 42-1
806 55.4 808- 86-2 806- 527 8St 556
807- 54-2
807-, 54-4
807-201808-153S08-15580-185-
3765
3765 3769
3312 3207 aml
8799 3876
1753 1781 3768
.3423 3771
3763
8836 3883 2774 3837
4254 2ss 2860
." S
.30
366 367
Tampa from
D, S D. 8
D G, S
D, S
S
*82 115
a
a
6
a 58 68
a
a
a
a
185 135 136 165 207 178
145 132 123 18839
163
140 136
e210 1836
135
142 137
138 152
-125
8
OX G. S GS D G. 8 D, G, s D, G, 8 D, S D, S. X
D' G, 5, X
. G. S
38 D. S
JI S
D; ,
8
DIS
, , S
S
DG, 8, x A8 D, S D, 0, S D, S 'x. , s D, G, S, X G X
D".
not elearly evident
samples-no driller's
Fust sample at no driller * log.
140'-
Top Lake City 1028~ top Oldmar 14-15 W 50' west of W-148
Questionable samples. Top lake City 111(Y.
&lOI-136-2 4863 809-136-4 2013 80-147-1 4275 809-148-2 5045 809-153-3 386
8 0-136-1 . 8 .0-144-1 4990 8"0-148-1 . 8-0-151-2 . 8_0-154-1 3867 ' 8 0-155-1 3866 8 1-138-3 4919 & 2-135-1 46412
8 3-249-1 50416 1 -201-1 5352 . .4-139-4 5348
8 4-148-1
4 5-188-1 4906 4 5-142-1 2133 8 5-157-2 3839 8 6-148-1 4689 8 8-151-2 . 8 9-140-1 5016 8 9-147-1 .
Sumter County: 821-2023 5054
Pasco County: 816-206-1 5850
Hillsborough County: 742-216-1
744-226-10 .
745-215-1 .
751-203-1
io 131 135 179 136 113 138
168 152
129 129S 175 116
132 105 e150 130 173
143 109
128 124 213 128
clil 92
a 122
a 83
a
c
a
a
222 110
a
a 167
a
a
a
a
a
a
a
c
96 a
a
a
a
a
a a21 l147
e@s 230
a
a 17
a
a
a
a
a
a
a
a
a
21
147 302
115
C 17
155
200
257
246
219 128
260
247
125 220
160
154 90
123
145 126 235 C97
D. c. S, X D, S D. S D, S
X
D, 0, X
S
X"
D, G. X
S
D, 8 D. , S
D, G, S, X
S
D, S
S
D, G, S. X D. S. X D. , X D. S
P.S
72 101 136 D, G, SO .
40 e310
460 2M8
8) 157
irreui;ar sanidta
.44
Wgi to 65 Buried sinkhole
Tampa Elay not indicated in samples or driller's log.
Wgi 1077
Avon Park top indicated also
by gammaray lops.
190 D, 8, X
S
,. . - --.
S
. . . X
. . . I
. . . X
Intelpretation by HI. 31.
Peek9,(959, fi 15)
FLORIDA GEOLOGICAL SURVEY
the usage of the U.S. Geological Survey, with the exception of the Ocala Group and its subdivisions, and the Tampa Formation of Miocene age. The Florida Geological Survey had adopted the Ocala Group as described by Puri (1957), but the U.S. Geological Survey includes these strata in the Ocala Formation and the underlying upper part (= Inglis Limestone of former usage) of the Avon Park Limestone. The Tampa Limestone, as used by the U.S. Geological Survey, is referred to as the Tampa Formation by the Florida Geological Survey.
EOCENE SERIES
OLDSMAR LIMESTONE
Vernon (1951, p. 87, 92) and Cooke (1945, p. 40, 46) indicate that the Oldsmar Limestone probably underlies all of peninsular Florida, and that the thickness of the formation may range from 300 to 1,200 feet. They further indicate that the Oldsmar unconformably underlies the Lake City Limestone.
Four test holes in Polk County penetrate the Oldsmar Limestone. Applin and Applin (1944) examined the samples from well 750-148-1 and placed the 670-feet interval from 1,960 to 2,630 feet in the Oldsmar. The cores and logs from two deep exploratory holes drilled near Lakeland furnish much of the geologic information used in this and the following sections on stratigraphy. One core hole, about 3 miles southwest of Lakeland (well number 801200-3), was drilled to a depth of 1,842 feet. The other core hole, about 5 miles northeast of Lakeland (805-154-8), was drilled to a depth of 1,479 feet. Both of these holes terminated in the Oldsmar Limestone. The abstracted logs of these two holes are given here to aid in the discussion.
Core Hole 3 Miles SW of Lakeland (801-200-3)
Altitude of Land Surface is Approximately 135 feet above msl.
DEPTH IN FEET,
MATERIAL BELOW LAND SURFACE
Undifferentiated:
Sand and clay. 0-14
Hawthorn Formation:
Limestone. 14-93
Tampa Formation:
Clay, blue-green. 93-135
REPORT OF INVESTIGATION No. 44 Core Hole 801-200-3-Continued
MATERIAL
DEPTH IN FEET,
BELOW LAND SURFACE
Suwannee Limestone (start core at 139 ft.
3 in.): Chert, dark gray, very hard; replaced limestone, with pre-chert solutional cavities up to 2 ', inches, filled with cream limestone containing Sorntes ap. Drilling
water circulation lost at 138 feet. Identified:
Not cored from 142%A to 652 'd; all drilling water circulation lost, no cuttings returned.
Avon Park Limestone:
Open cavern.
Sand and mud (driller's interpretation),
probably cavern-fill, very soft.
Open cavern, casing slipped to bottom of
hole.
Casing set by water-jetting only; probably
sand and mud cavern-fill, very soft.
Casing set by water-jetting and casing rotation only; probably extensive honeycomb, and/or sand and mud cavern-fill, very soft. In Avon Park Limestone (cored from 652 ft. 11 in. to total depth 1,842 ft.):
Dolomite, replaced limestone, dark brown, dense, broken and highly fractured (some
re-cemented). (See figure 4.)
Dolomite, as above, with solution cavities up to 2% inches, and one open vug (after gypsum) containing small amounts of loose brown dolomite sand. Cavities are developed along fractures in cavern collapse
rubble.
Dolomite, as above, cavern-fill developed in
dolomitized collapse rubble (fill).
Dolomite, as above, badly broken to resemble coarse gravel. May include a continuation of pre-dolomite collapse zone above.
Dolomite, as above, a collapse rubble of angular dis-oriented inclusions in finer grained matrix. Cavities developed and partly filled with brown dolomite sand (?).
Dolomite, as above, badly broken in zones.
Dip-slip faulting or slumping, and repetitive thin beds due to overriding thrust.
135-1421/
440-445
445-455 540Y'2-5471, 547Y/2-576
576-653
653-665
665-670 670-673 673-684
684-685% 685 %-703
703-
FLORIDA GEOLOGICAL SURVEY Core Hole 801-200-3-Continued
MATERIAL
DEPTH IN FEET,
BELOW LAND SURFACE;
Thrust fault cutting a chert nodule. Slicklenslides on nearly horizontal beddingplane thrust.
Dolomite, as above, locally broken and fractured. A few small solution cavities developed (vugs after gypsum?)
Dolomite, as above, a dolomitized rubble.
Angular inclusions up to 1% inches, in finer grained matrix, have random orientation. Believed of collapse origin, but possibly a pre-lithification sedimentary rubble.
Dolomite, as above, badly broken and fractured in some zones.
Dolomite, as above, collapse rubble, angular inclusions up to 2 inches in heterogenous matrix, with random orientation of
inclusions.
Dolomite, as above, massive and dense to badly broken in zones, occasional solution
cavity up to % inch.
Clay. a sedimentary rubble.
Limestone, soft, chalky; some fine to very fine honeycomb development and occasional
cavities up to 1 inch.
Limestone. soft to hard in zones, solution tubes
up to '. inch diameter and fine honeycomb
development.
Limestone, dolomitic?, hard with fine honeycomb development.
Limestone, moderately soft, with tubes and
cavities up to % inch.
Lake City Limestone:
Limestone, soft to hard, chalky zones, low permeability with occasional fine honeycomb, abundant nodules and nests of nodules of gypsum altered from anhydrite.
Abundant and general impregnation by selenite. Some open pore-space and molds,
but not common.
Dolomite, replaced limestone, very hard, general selenite impregnation, but some open pore spaces, small tubes and cavities, gypsum nodules altered from anhydrite.
Fractures, vertical to high-angle, in lower
part are re-cemented by selenite.
703Y
703-722%M
722 %-725 %, 725 1-742 %
742 -746Y 740 'A-778Ma 778 -780
780-875 875-951
951-1,068 1,068-1,128
1,128-1,451
1,451-1,588
REPORT OF INVESTIGATION No. 44 Core Hole 801-200-3-Continued
MATERIAL (Con't)
DEPTH IN FEET,
BELOW LAND SURFACE
01,1smar Limestone:
Dolomite, hard, pore space as molds and fine honeycomb, generally selenite impregnated; gypsum nodules altered from anhydrite, some selenite cemented fractures.
Sonic thin zones of dolomite sand (?).
Dolomite, as above, dolomite sand (?) zones more numerous and thicker with very high porosity; a few scattered open vugs after gypsum (?) excavation. Gypsum nodules altered from anhydrite. Selenite impregnation of dense dolomite zones.
Dolomite, as above, abundant nests and scattered gypsum nodules altered from anhydrite; selenite as impregnation and fracture cement.
Anhydrite, white, massive, single bed.
Dolomite, as above, scattered anhydrite and gypsum nodules, scattered occurrences of dolomite sand (?), extensive selenite impregnation of massive dolomite, and postdolomite fractures.
1,588-1,688 1,688-1,746
1,746-1,812 1,812-1,816 1,816-1,842
Core Hole 5 Miles NE of Lakeland (805-154-8)
Altitude of land surface is approximately
130 feet above msl.
Undifferentiated:
Sand and clay.
Ilawthorn Formation:
Limestone.
Tampa Formation:
Clay, blue-green. Stiwannee Limestone:
Limestone, detrital, very soft, chalky, little
evidence of solutional activity. Oc'la Group Cr,7stal River Formation:
Limestone, soft, granular to very chalky,
little evidence of solutional activity. N illiston Formation:
Limestone, soft to moderately hard, granular, local dolomitized zones, some solutional
removal of calcite matrix.
0-50 50-58
58-60 60-151
151-276
276-286
FLORIDA GEOLOGICAL SURVEY
Core Hole 805-154-8-Continued DEPTH IN FEET, BELOW LAND SURFACE
Inglis Formation:
Limestone, granular, soft to hard, locally dolomitized, note solutional removal of cement and fossil molds, fine solutional tubes,
and local honeycomb. Avon Park Limestone:
Limestone, hard to soft, granular to chalky, visible porosity moderate to very
high in granular zones.
Dolomite, replacement of limestone, very hard and dense; solution tubes I inch x 14 inch diameter. (First such features noted.)
Lost drilling water circulation.
Dolomite, replacement of limestone, very hard; dense to granular, low to very high
visible porosity.
Lost drilling water circulation.
Fine honeycomb.
Dense, badly broken, as dolomite
6"gravel."
Dense, thin bedded, with zones of fine
honeycomb.
Badly broken, as gravel, some solution
along fractures.
Badly broken, as gravel, in zones.
Collapse rubble zone; angular inclusions up to 4 in. Random orientation, one 3 in. piece is thin-bedded with beding-tipped vertical, matrix fine-grained
and thin bedded.
Collapse rubble, angular, badly broken.
Dense, badly broken.
Collapse rubble, very angular inclusions up to 2 in. Random orientation, yellow thin-bedded inclusion tilted with bedding at high angle to core. Some solution along fractures through interval.
This interval may be essentially continuous from 574 .
Dense, badly broken.
Limestone, moderately soft, very fine honeycomb developed.
Limestone, soft to moderately hard, some small tubes and fine honeycomb. At 685 feet first open vug from removal of gypsum alteration of anhydrite nodules.
286-345%
346-4441/k
4441/-449%
512
521-615
529
534-536 538-542
542-552 552-553
556-564
566-567 5741/2-575
575-5781'A
578 %-588 597-610% 621 'A -623 %
623% -685
25
REPORT OF INVESTIGATION No, 44 Core Hole 805-154-8-Continued
Limestone, collapse rubble, middle 1% foot
dolomitized. Post dolomite fractures.
Collapse rubble continues from 695; core shows old cavern wall and fine-grained fill with larger inclusions. Badly broken in lower part; fine second-stage solution honeycomb developing in dolomite.
Dolomitized collapse rubble with postdolomite fractures.
Limestone, generally chalky and soft to moderately hard in thin local partially dolomitized zones. Visible porosity low to moderate due to fossil molds and fine honeycomb development. Numerous large (to 2 -in.) irregular vugs resulting from solutional excavation of gypsum altered from rubble of anhydrite nodules. Abundant calcite crystals in vugs below 879 feet, and a few quartz crystal growths noted. Occasional silicified clay beds a few inches
thick.
Lost drilling water circulation; regained and partial loss of circulation again at 796
feet.
Limestone, chalky, very soft to moderately soft, heavy selenite impregnation of pores and molds. Nodules of gypsum (after anhydrite) up to 1/ in.
Lake City Limestone (1,028-1,445%h):
Limestone, chalky, soft; contains irregular, rounded, nodules of gypsum altered from anhydrite rubble. Profuse selenite impregnation of pore space, but some small open solutional cavities and fossil molds noted.
Visible porosity generally low.
Limestone, dolomitic, with gypsum as above.
Dolomite, replaced limestone, hard, crystalline. Gypsum nodules as above, selenite impregnation, and some small open pore
space.
Dolomite, as above, with small cavities containing dolomite-sand fill. Gypsum as
above.
Limestone, dolomitic, moderately soft to moderately hard, low porosity. Selenite impregnation and gypsum as above. Occasional open vug after gypsum.
DEPTH IN FEET,
BELOW LAND SURFACE
695-698
698-704 716-717
717-1,015%
785
1,015% -1,028
1,028-1,295 '/
1,295%-1,374%
1,374/2-1,386
1,386-1,3921%2
1,392h-1,445
FLORIDA GEOLOGICAL SURVEY
Core Hole 805-154-8-Continued
DEPTH IN FEET,
BELOW LAND SURFACE
Oldsmar Limestone (1,445%-1,479):
Limestone, dolomitic, moderately hard.
Small gypsum nodules as above, a few small vugs after gypsum. Some selenite
impregnation and fine honeycomb. 1,445Y -1,459
Dolomite. replaced limestone, dense, hard; scattered gypsum as above, and some selenite impregnation; fine honeycomb zones
and rare small open vugs after gypsum. 1,459-1,479
On the basis of the major change in character of the electric and gamma-ray logs, and lithology, the lower 331/ feet (1,4451. 1,479 feet) of well 805-1,54-8 and the lower 258 feet (1,588-1,846 feet) of well 801-200-3 are tentatively designated as Oldsmar Limestone.
In wells 801-200-3 and 805-154-8, the Oldsmar is a grayish-tan to brown, very hard, finely crystalline, highly dolomitized, gypsiferous limestone. Generally, dolomitization appears to follow bedding planes and is inter-bedded with a few soft, calcareous zones. Color of the formation becomes more grayish downward with increasing amounts of disseminated peat.
The formation contains rubble-beds which are generally less than a foot thick, which were formed before the sediments were firmly cemented and lithified. These are interpreted as bottom sediments which have been broken up by wave action while in a semi-plastic state, then re-deposited and cemented. Such changes may reflect storm waves of greater than normal proportions. The formation also contains sequences of thin, individual graded-beds, each bed being only 1 or 2 inches thick. These graded-beds, and the rubble-beds, indicate rapidly changing sedimentary conditions iii a relatively shallow sea or embayment. Such changes may have been short-lived and of generally small magnitude. Thick peat a,,,cumulations at the top of the formation were interbedded with rubble-beds. Other rubble-beds were found throughout the formttion. Further study of such features in these two wells will provide more information about the environment of deposition of tie formation.
In wells 801-200-3 and 805-154-8 in the Lakeland area, the corltinuous cores from the Oldsmar Limestone contain considerable amounts of anhydrite, gypsum, and selenite, a clear crystalline variety of gypsum. A solid bed of anhydrite was encountered frown
REPORT OF INVESTIGATION No. 44
1,1 [2 to 1,816 feet in well 801-200-3. With this exception, the an iydrite and gypsum in the Oldsmar occurred as rounded irregulhtr nodules that are several inches long in the greatest dimension. The nodules were not apparently oriented and were scattered as individual nodules or deposited in clusters that seldom exceeded a foot in thickness. The nodules were originally anhydrite and all but a few in the lower part of the formation have been partly or completely altered to gypsum by varying degrees of hydration. Most of the gypsum nodules contain a large core of unaltered anhydrite. This alteration is accompanied by a 30-50 percent increase in volume (Pettijohn, 1949, p. 356), and the increase was evidenced by the fracturing and filling of adjacent limestone stringers and walls. The evaporites usually originate as bedded deposits in closed shallow basins. The occurrence here as separate nodules is interpreted as being the rubble of originally bedded deposits which have been destroyed by wave action. The size and shape of the nodules suggest that the rubble was transported a relatively short distance before re-deposition. Such an interpretation is consistent with that of the pre-lithification sedimentary rubble beds mentioned previously. Selenite occurred in much of the formation as an impregnation of pore spaces and as fracture filling or cement. The selenite probably represents a further alteration, or solution and precipitation, of gypsum. Several small nodules of gypsum have been completely dissolved leaving open vugs in the rock. These vugs have intricate irregular walls like those enclosing the nodules cut by the drill, and there can be no doubt as to the origin of the vugs.
In the core samples from wells 801-200-3 and 805-154-8 the contact of the Oldsmar with the overlying Lake City Limestone is iiidefinite and appears to be a disconformable zone, rather than an erosional unconformity. The disconformable zone appears to be about 30 feet thick and contains large quantities of peat or low-grade lignite. The peat is thought to be of marine origin and to represent a long period of very shallow water conditions and ll tie deposition. The presence of gypsum and anhydrite nodules in th:e disconformable zone and subjacent beds of the Oldsmar indic:Le the absence of fresh water erosion or circulation of fresh . 'ound water after deposition.
Excellent correlation of the disconformable interval was made b' gamma-ray logs of the two wells, which showed marked inc eases in radioactivity in the thick peat zone at the top of the f ration. The disconformable zone appears to be unfossiliferous,
FLORIDA GEOLOGICAL SURVEY
but this may be partly due to intense dolomitization and resultiutl destruction of fossils. The peat occurs as beds from 6 to 14 inches thick, as thin seams and bedding-plane films, and as disseminated! flakes. Only a slight change in color and lithology may be noted iln passing downward from the Lake City Limestone into the Oldsmalr Limestone.
In wells 801-200-1 and 805-154-8 the formation has very lov. visible porosity and permeability. Both porosity and permeability seem to increase in fractured dolomitized zones, but some of these zones have been partially re-cemented or filled with selenite. The presence of selenite, gypsum, and anhydrite throughout the for. mation clearly shows that there has never been a significant amount of fresh ground water in it, because these minerals ar soluble and would have been removed.
LAKE CITY LIMESTONE
The Lake City Limestone is penetrated by relatively few wells in this county, and only four wells are known to pass entirely through the formation.
According to Cooke (1945, p. 46), the formation underlies all but the northwestern part of the state. Samples were not collected from this formation in well 811-149-1. According to Cooke (1945 p. 48), the Lake City was encountered in well 750-148-1 at a depth of 1,540 feet, and it extends to a depth of 1,960 feet.
In well 805-154-8 a selenite and peat (?) replacement of Dictyoconus amcricanws, the index fossil of the Lake City, was recovered from the core at a depth of 1,0281/, feet. Identificatioji was based on the internal cell structure as illustrated by Applib and Jordan (1945, p. 136, fig. 2). Other specimens were observed in the core at this depth.
The electric log of this well shows a decrease in both resistivity and self-potential at a depth of 1,028 feet in a moderately soft, clayey, chalky zone of low visible porosity. The top of the forration is therefore placed at 1,028 feet in this well, and the forriition continues to a depth of 1,4451/ feet. The formation top oil this electric log correlates very closely with the electric log of nearby well 807-154-4 at a depth of 1,110 feet. This depth (1, 10 feet) also coincides with the first occurrence of chert and gypsili in the well according to a log prepared by E. W. Bishop of .hc Florida Geological Survey (FGS W-3883, July 17, 1956). BisIoP (op. cit.) designates the interval 1,110-1,198 feet as Avon Purk
REPORT OF INVESTIGATION No. 44
linestone. In well 801-200-3 the Lake City Limestone is identified in the interval from 1,198 to 1,588 feet by correlation of electric and gamma-ray logs with those of well 805-154-8. On the basis of these three wells, the thickness of the Lake City Limestone ranges from 417/_ to 420 feet in Polk County.
In wells 801-200-3 and 805-154-8 the Lake City Limestone is a white to cream, moderately soft to hard, chalky limestone. The lower 75 to 130 feet of the formation contains finely crystalline, highly dolomitized zones which appear to follow bedding planes. Thlie formation contains abundant peat films on bedding planes. Scattered chert nodules occur in the upper part of the formation and few thin apparent chert "beds" in the lower part of the formation may actually be small nodules or lenses. All of the chert appears to be of secondary origin as a replacement of limey sediments. Pre-lithification sedimentary rubble-beds, generally a few inches thick, are abundant throughout the formation in both wells 801-200-3 and 805-154-8.
In wells 801-200-3 and 805-154-8 the Lake City Limestone contains abundant anhydrite, gypsum, and selenite. The nodular mode of occurrence of these minerals in the Lake City is the same as that previously described in the Oldsmar Limestone. The same interpretation of origin and alteration, from original bedded anhydrite to nodular gypsum and selenite, also applies to the Lake (ity. However, the Lake City in these two wells does not contain bedded, or unaltered nodules of anhydrite. In general, the anhy(trite cores of the nodules decrease in size upward and completely altered nodules of gypsum are common. Individual nodules reach as much as 12 inches in their greatest dimension. Selenite impregnation of pore spaces, small solutional tubes and cavities, small vugs, and fractures occur throughout much of the formation. Open vugs, generally less than 1 inch in diameter, resulting from solutional removal of anhydrite-gypsum nodules occur throughout the formation. These are relatively few in number, but are more numerous than in the Oldsmar.
Cooke (1945, p. 46) and Vernon (1951, p. 92, 99) indicate that t'!e contact of the Lake City and the overlying Avon Park Limes one may be unconformable. In the cores from wells 801-200-3
Id 805-154-8 the contact zone is not obvious. In well 805-154-8 V JPSum nodules occur at 1,038 feet, 10 feet below the contact. In i' ell 801-200-3 gypsum nodules occur throughout the contact zone " id adjacent beds. The occurrence of gypsum nodules and the cont nuity of lithology strongly suggest that the contact is transi-
Pages Missing or
Unavailable
FLORIDA GEOLOGICAL SURVEY
and their significance will be discussed in more detail in the see tion on solutional features.
The Avon Park contains anhydrite-gypsum nodules in the same, mode of occurrence as has been previously described in the Oldsmar and Lake City Limestones. The same interpretations of origit and alteration, from original-bedded anhydrite to nodular gypsun and selenite, stated for these earlier formations is also applied to the Avon Park. However, in wells 801-200-3 and 805-154-8 the Avon Park does not contain unaltered anhydrite, and it now contains considerably less total anhydrite, gypsum, and selenite thani the two underlying formations. In well 801-200-3, the cored well southwest of Lakeland, the Avon Park contained scattered gypsum nodules and clusters and selenite impregnations only in the lower 70 feet (1,128-1,198). In well 805-154-8, northeast of Lakeland, the Avon Park contained such deposits only in the lower 13 feet (1.015-1,028). In both wells the gypsum nodules contained cores of anhydrite.
There is no doubt that the Avon Park once contained a much greater amount of the evaporate nodules. In well 805-154-8 many open vugs with irregular, concavely rounded walls, occurred at depths of 685 to 885 feet. It seems clear that these vugs result from the complete solutional removal of evaporite nodules. The open vugs were scattered and sparse in number from 885 to 1,015 feet. Only a few vugs were found in the cores from well 801-200-3 and these occurred from 829 to 1,128 feet.
The Avon Park Limestone contains numerous thin, porous, granular, sand-like zones of dolomite, the origin of which is unknown. There are several suggested origins that may be possible:
(1) Some zones may be a depositional dolomite-sand in solutional cavities; (2) some zones may be an ultra-fine honeycomb developed along fractures and other openings by solution; and (3) some of the zones may be the result of precipitation of ultra-fine dolomite crystals. Such zones are also found in the dolomitized zones of the underlying Lake City and Oldsmar Limestones.
The formation also contains, particularly in the lower part, numerous chalky or clayey zones; some thin, well-defined calcareous clay beds; and abundant peat as thin films on bedding planes. There are also chert nodules, apparent chert beds, and diffused silicified zones.
Vernon (1951, p. 99) states that both of the formational contacts are erosional unconformities. The present studies of cores from wells 801-200-3 and 805-154-8 in the Lakeland area, and
REPORT OF INVESTIGATION No. 44
,any sets of cuttings indicate that the contact in Polk County is .:nconformable. The lower few feet of the overlying Inglis For.ration generally contain pieces of dark, granular rubble up to I-inch diameter and abundant eroded Dictyoconus sp. and oskiolia sp. from the Avon Park. This is interpreted as weathered Avon Park Limestone, eroded and re-deposited in the early stages of Inglis deposition and hence an unconformable contact.
Permeability of the formation ranges from very low in some of the clayey or chalky zones to extremely high in cavernous zones. The visible porsity and permeability of the formation, as a itit, is high and it is the greatest water-producing unit in the Floridan aquifer in Polk County. Local areas in which the forination as a whole is of low permeability have been encountered, but these are relatively few in number.
OCALA GROUP
In recent years the Florida Geological Survey has subdivided the rocks formerly grouped within the Ocala Limestone. Vernon (1951, p. 113-171) divided this sequence of rocks into the Ocala Limestone (restricted) and the Moodys Branch Formation. He divided the Moodys Branch Formation of his usage into two parts. The lower unit was named the Inglis Member, and the upper unit wtas named the Williston Member.
Puri (1953a, 1957) gave the name Crystal River Formation to Vernon's restricted Ocala Limestone and gave formation rank to Vernon's Inglis and Williston Members of the Moodys Branch Formation. The Crystal River, Williston, and Inglis Formations are now referred to as the Ocala Group by the Florida Geological Survey and the name Moodys Branch Formation is no longer used in Florida. The northeastern half of Polk County is underlain by the Ocala Group as shown in figure 5.
Inglis Formation
The Inglis Formation underlies almost the entire county except in local areas in northeastern part and is a white to cream to dark brown, generally hard to very hard, granular, partially to highly dolomitized, highly fossiliferous limestone with some local soft chalky zones. In the area lying generally north and west of Polk City, the formation is highly dolomitized, very hard and contains many sand-filled solutional cavities.
In the central part of the county the formation has a relatively
FLORIDA GEOLOGICAL SURVEY
uniform thickness of 35-45 feet. In well 821-202-3 in Sumter County, northwest of Rock Ridge (fig. 4), the Inglis is 29 feet thick. This well is located along the crest of the major structural feature in the area. In well 805-154-8, northeast of Lakeland, the Inglis is approximately 50 feet thick. It thickens slightly along the extreme western part of the county to about 45-50 feet. In the southeastern part of the county the Inglis is as much as 95 feet thick.
Figure 5. Geologic map of the pre-Miocene formations.
The Inglis is the uppermost limestone in extreme northeastern Polk County due to erosion of the overlying beds along the crest of a structural high. The Inglis conformably underlies the Williston Formation, and unconformably, overlies the Avon Park Umestone. (Vernon, 1951, p. 212).
In well 805-154-8 the Inglis appears to have low to moderate porosity in the upper part of the formation. Moderate to high visible porosity in the lower part of the formation is due to the
REPORT OF INVESTIGATION No. 44
-emoval of the calcite cement and matrix in the granular and ossiliferous zones. The Inglis is one of several formations usually penetratedd by water wells in this area. Locally it may be a good producer due to cavernous conditions and/or its generally granular texture. However, wells are not usually drilled for the purpose of obtaining water from this formation.
Williston Formation
The Williston Formation is a white to cream to brown limestone, and is a generally soft, coarse, coquina of foraminifera, set in a chalky calcite matrix. The lower 5-15 feet are usually harder than the rest of the formation due to dolomitization. The formation has moderate visible porosity. The Williston is generally less highly dolomitized than the underlying Inglis Formation.
T he formation underlies most of the county with a thickness which ranges from 10 to 100 feet, and averages about 30 feet. These thicknesses are based principally upon electric-log determinations. In extreme northeastern Polk County the formation is missing, having been removed by erosion, and may be missing from other local areas near the crest of the structural high.
Vernon (1951, p. 143) states that the formation lies conformably between the Inglis and the overlying Crystal River Formation. The lower contact is marked by a distinct lithologic change, but the upper contact is transitional and very difficult to define.
The Williston is one of several formations usually penetrated by water wells in this county, and it is believed to contribute some water to wells. The general character of the formation (soft, coquinoid, and chalky matrix) results in a lower porosity and permeability, as compared to the more productive underlying formations.
Crystal River Formation
In the subsurface the Crystal River Formation is a white, gray, cream, or tan, generally very soft, coarse, granular, limestone of very high purity which contains great numbers of large foraminifera in a chalky carbonate matrix. Locally it may contain thin hard -dolomitized beds or zones which are controlled by bedding.
The Crystal River is easily recognized from the abundance of disc-shaped foraminifers of the genus Lepidocyclina. In some of the species the disc has a saddlelike shape. The formation com-
FLORIDA GEOLOGICAL SURVEY
monly is referred to as "Ocala," "shell," or "limeshell" by local drillers.
The formation ranges in thickness from 80 to 125 feet in an east-west belt across the county between Lakeland and Ft. Meade. South of this belt it thickens gradually southward to 150 feet, possibly even thicker locally. North of the belt, it ranges from 30 to 60 feet in thickness due to erosion and has been entirely removed from broad areas lying northeast of Polk City. The formnation has been removed by erosion in the vicinity of eastern Winter Haven, where the Williston Formation appears to be directly overlain by the Suwannee Limestone. Both the Crystal River and Williston have been removed by erosion from the vicinity of Haines City and the Inglis is directly overlain by the Suwannee Limestone.
The Crystal River is the uppermost Limestone in the northern part of the county due to erosion of the overlying Suwannee and younger formations. Along the crest of the structural high area in northwestern Polk and adjacent parts of Lake and Sumter counties, the Crystal River Formation is at, or within a few feet of the surface over an area of approximately 100 square miles. This outcrop area has not been previously mapped or described in any literature. The outcrop area was mapped and studies in a reconnaissance by E. W. Bishop, geologist, Florida Geological Survey, and the author in April 1957. The results are discussed here with the permission of Mr. Bishop."1
Throughout the area of surface exposure the limestone is silicitied by replacement with hard, dark gray to white chert. In these exposures the fossil content has been generally destroyed by the replacement, but locally small concentrations of Lepidocyclina nealaa were found. Lepidocyclina ocaloana is a diagnostic fossil of the Crystal River and is usually abundant in the formations.
Numerous echinoids were observed in many parts of the outcrop area. In some locations the echinoids were found adjacent to occurrences of Lepidocyclina ocakina. More than 40 specimens of echinoids were collected, and they appear to represent a single species. Nine of the best specimens from the area of outcrop, and one from a limestone pit at Lacoochee, Pasco County, were identified as Rhyncholampas (Cassidulws) gouldii (Bouve) by 1Mr. Porter Kier, Associate Curator, Division of Invertebrate Paleontology and Paleobotany, U.S. National Museum .4 CassiduPersonal communication, E. W. Bishop, December 12, 1960.
Personal communication, Porter M. Kier, April 10, 1961.
REPORT OF INVESTIGATION No. 44
ius gouldii (Bouve) is a diagnostic fossil of the Suwannee Lime-,tone of Oligocene age, which normally overlies the Crystal River.
The echinoids are preserved as filled molds, the filling being .t miliolid-rich granular limestone. In one such echinoid, a specimen of Dictyoconus cookci was found and, although this foraminifer is diagnostic of the Avon Park Limestone, it is also frequently found in the Suwannee Limestone.
Because of the observed association of Suwannee and Crystal River fauna the outcrop area is interpreted as being the. eroded remnant of the original contact zone of the two formations. Such interpretation thus places the thickness of the Crystal River on the crest of the Ocala uplift at 60 feet or less. Only one outcrop of slightly calcareous limestone was observed.
A well in the outcrop area in southern Sumter County, 821202-3, penetrated 72 feet of the Crystal River Formation.
Surrounding the area of outcrop is a broad belt of boulders and isolated boulders and cobbles. The closeness of the formation to the surface is inferred by the presence of many silicified and sparsely fossiliferous boulders and cobbles in the spoil piles or in the bottoms of the extensive shallow drainage canals in the area. Many of the boulders and some of the outcrops showed extensive solutional erosion prior to silification. It is evident that some of the boulders were originally geodes or parts of small caverns' that were armored through replacement by, or deposition of, gray to white chert, while the main body of limestone remained unaltered and soluble. Subsequently the soluble limestone portions of the formation were removed by chemical and! or mechanical erosion, during exposure at land surface, leaving the resistant silicified solutional features. Several boulders contained solutional cavities lined with banded, botryoidal, amorphous chalcedony, and geode-like, clear, quartz-crystal growths.
The Crystal River, according to Vernon (1951, p. 160) lies conformably upon the Williston Formation and is unconformably overlain by the Suwannee Limestone of Oligocene age, or by younger unconsolidated clays and sands.
In well 805-154-8 the Crystal River is 124 feet thick and has low to moderate visible porosity and permeability. Small incipient solutional tubes and cavities were observed in the interval from 182 to 224 feet. Cores were not taken from this formation in well 801-200-3.
The yield of wells terminating in the Crystal River Formation is considerably less than those drilled into the Avon Park Lime-
FLORIDA GEOLOGICAL SURVEY
stone, due to the very soft, chalky matrix. The yield of such a well can usually be increased by deepening the well into one or more of the underlying formations. The formation will generally produce a sufficient quantity for domestic supplies.
OLIGOCENE SERIES
SUWANNEE LIMESTONE
The Suwannee Limestone is white, cream, or tan, generally very soft, granular, detrital limestone which is generally - very pure. Locally, however, it contains a small amount of fine quartz sand as disseminated grains. It contains abundant bryozoa, small mollusca, and large echinoids. Local drillers refer to it as the "4coquina." In some places the upper surface, and/or a zone near the middle of the formation, is replaced by dark-brown or gray chert which commonly ranges from a few inches to a few feet thick. The greatest thickness of chert encountered, or reported, in the county was 10 feet in well 803-156-11 in Lakeland. The chert zone occurred from 208'/A to 218%/. feet, near the middle of the formation. The area of Polk County underlain by the Suwannee Limestone is shown in Figure 5.
In well 805-154-8 the formation is 91 feet thick and contains thin hard dolomitic zones from 73 to 75 feet. The formation contains some small solutional tubes and cavities which are lined with small calcite crystals. The lower portion of the formation is chalky and less granular than the upper part. The Suwannee in this well has a moderate to low visible porosity and permeability. The lower few feet appear to be an indistinct pre-lithification rubble zone, and contain films of black peat along bedding planes.
The thickness of the Suwannee' in well 801-200-3 is unknown due to loss of cuttings and circulation at 136 feet. In this well, however, the upper 3 feet of the formation was cored, and is a complete replacement by gray chert. The silicification preserved in detail many solutional cavities in the limestone. Some of these cavities contained a filling of cream colored sandy limestone, which contained a number of Sorites sp., and which is tentatively identified as limestone of the Hawthorn Formation of Miocene, age. This clearly establishes one reason for the finding of this particular fossil, as reported by Stewart (1959, p. 22), in what might otherwise be considered as slightly sandy Suwannee Limestone.
REPORT OF INVESTIGATION No. 44
Thickness of the Suwannee generally ranges from 80 to 120 Fleet in the central and southern parts of the county. It thickens rather abruptly from 70 feet in a well southwest of Lakeland (759-201-1), to 195 feet in a well in south-central Hillsborough County (746-209-1). In the northern part of Polk County the formation thins considerably due to both depositional and erosional thinning, and is absent in much of the northern and eastern parts of the county (fig. 5).
In several sets of well cuttings the Suwannee Limestone contained some fossils that are diagnostic of the Crystal River Formation. Some of these samples also contained a few specimens of the Suwannee foramanifer Rotalia mexicanct, which is not a durable fossil. Such rocks, though containing predominantly Crystal River fossils, are interpreted as Suwannee Limestone. They indicate local erosion and re-deposition of Ocala rocks during deposition of the Suwannee. An example of such deposits was found in the upper 36 feet of limestone in well 800-142-1.
The yield of wells terminating in the Suwannee Limestone is considerably less than those in the Avon Park Limestone, but is generally greater than the yield of wells in the Crystal River Formation. The Suwannee furnishes adequate supplies for domestic and small irrigation wells, and it is widely used for these purposes.
MIOCENE SERIES
The correlation of the formations of Miocene age in Florida and adjacent states has long been a major geologic problem. Recently great strides have been made with this problem in the Florida panhandle by Puni (1953b). Major problems still exist, however, in the peninsular part of the state. Reports by Bergendahl (1956, p. 69-84), Cooke (1945, p. 109 ff), Vernon (1951, p. 178-186), Puni (1953b, p. 15 iff), and others contain summaries of the problem.
In recent years the Miocene and younger deposits in the central part of the peninsula have been studied by many geologists of the U.S. Geological Survey. Some of the findings are reported by Cathcart and McGreevy (1959), Ketner and McGreevy (1959), Carr and Alverson (1959), Altschuler, Jaffee, and Cuttitta (1956), Altschuler, Clarke, and Young (1958), Altschuler and Young (1960), and others. With these recent contributions some of the questions regarding the Hawthorn and Tampa Formations may have been resolved, but in the case of the limestone units
FLORIDA GEOLOGICAL SURVEY
ofT these formations, which are widely used ground-water aquifers, a basic practical problem of identification and delineation still exists.
The chemical and lithologic constitution (Carr and Alverson, 1953, p. 175 iff) of the limestone units of the two formations is identical for field mapping purposes. The fossil fauna is largely mollusca which are not individually diagnostic of either formation, and faunal assemblages are only generally diagnostic of the early and middle Miocene ages presently assigned to the Tampa and Hawthorn Formation respectively (Vernon, 1951; Puri, 1953b; Espenshade and Spencer, 1963). Identification of .these formations is made even more unlikely in Polk County because of dolomitization and because most of the geologic work must be done from wvell cuttings, in which large mollusca molds are rarely recovered intact. Sorites sp., common to the Tampa but not diagnostic of it, has not been found in known exposures of the Hawthorn, but has been found in well cuttings in both typical Suwannee and Hawthorn lithology, thus complicating the problem further. Archajias floridanus, a foraminifer commonly accepted its diagnostic of the Tampa, has not been found in well cuttings in this area.
TAMPA FORMATION
Cole (1941, p. 6) identified the Tampa between the depths of 117 and 180 feet in a well 4 miles north of Lakeland (805-157-15) at the Carpenter's Home, on the assumption that the Tampa Formation underlies all of Polk County, and on the basis of general lithology, and an interpretation of fossil evidence. In his diagrammatic illustration of the well (op. cit., p. 5, fig. 2) he also includes the interval of 180 to 250 feet in the Tampa. This well was in use during the entire course of the present investigation, and exploration of the well was not possible. However, on the basis of an electric log obtained in well 805-157-16, approximately 50 feet west of the well described by Cole, the interval 117-250 feet was determined to be the Suwannee Limestone.
Cooke (1945, p. 132) states that the Tampa probably underlies all of Polk County south of Lakeland. Vernon (1951) does not discuss the Tampa Formation in his description of stratigraphic units. Cathcart an~d McGreevy (1959, p. 228) found the Tampa Limestone in western Polk and adjacent parts of other counties, and report it to be a sandy, clayey, limestone containing abundant chert fragments and very few phosphate nodules. They
REPORT OF INVESTIGATION No. 44
tate that the limestone is interbedded with clay and sandy clay, nd describe a locally developed residual mantle of green calcare(us clay which contains chert and limestone fragments and a ew phosphate nodules.
Ketner and McGreevy (1959, p. 59-65) consider the Tampa Limestone to consist of three units, only two of which are present inl Polk County. Their upper, so-called "phosphorite unit" lies ilorth of this county and does not occur in the area of this investigation. In northern Polk, according to Ketner and McGreevy, the Trampa is represented by a limestone unit and a clay unit. The clay unit consists of "greenish-gray to brown clay containing well-sorted, very fine- to fine-grained quartz sand. Sand ranges from 5 to 80 percent, averaging about 35 percent." They further state that the clay unit "apparently grades into the limestone unit of the Tampa about where the limestone unit of the Hawthorn Formation appears." Their limestone unit of the Tampa is described from an exposure in the Tenoroc Mine of the Coronet Phosphate Co., northeast of Lakeland, as being "fossiliferous, yellow, somewhat soft, clayey, and sandy. The sand consists of very fine- to fine-grained quartz and sand- to pebble-sized, rounded, polished phosphorite nodules." They do not describe the areal extent of the limestone unit, but identify it in two drill holes.
Carr and Alverson (1959, p. 14-33) present the most complete studies and discussions of the Tampa in recent years and extend the formation eastward from Tampa Bay as far as central Polk County. According to these authors, the Tampa is a white to light yellow, soft, moderately sandy and clayey, locally phosphatic, finely granular, and locally highly fossiliferous limestone. They state that both marine and fresh water limestones are present, and that both upper and lower contacts of the formation are erosional unconformities. Further, they state that limestone commonly interfingers with calcareous sandy clay which may be equivalent to, or be, the Chattahoochee facies of Puri (1953b, p. 20). If so, this is the first such recognition in this area. They describe a section of the formation near the Hillsborough River Dam as illustrating the interfingering of the clay and limestone beds. They state-"Most clayey beds in the Tampa limestone are small lenses, but several wells in Polk County, including two drilled in 1952 at the Davison Chemical Corp. in western Polk County, were drilled through about 50 feet of rather uniform greenish-gray dolomitic sandy clay. This unit is tentatively placed at the base of the Tampa; in the Davison wells it
FLORIDA GEOLOGICAL SURVEY
rests in sharp contact upon pure, white limestone containing Cassidulus gouldii (Bouve). The wells in which the unit 'was noted roughly delimit an area with corners near Mulberry, Lakeland, Winter Haven, and Fort Meade." The Davison wells referred to here are wells 754-155-1 and -3 of this report.
The Tampa Formation has been identified in relatively few wells in this county. Open-file logs of the Florida Geological Survey by E. W. Bishop and R. 0. Vernon identify the Tampa Formation from faunal evidence in a well south of Frostproof (742-131-2), and ' a well at Lake Wales (753-134-4). Examination of cuttings of the thick Miocene section in a well southwest of Lakeland (801-200-3), revealed no limestone in the Tampa Formation. Cuttings from wells 754-155-1 and -3 were studied and no evidence was found on which to base identification of Tampa Umestone units in these wells as identified by Carr and Alverson (1959, p. 25, and fig. 7).
Field evidence obtained during the.earlier phases of this investigation (Stewart., 1959, p. 22) did not justify an identification of limestone in the Tampa in northwestern Polk County. A slightly sandy limestone, similar in lithology to early descriptions of the Tampa was noted in northwestern Polk, and was tentatively placed in the Tampa. This has since been identified as Suwannee Limestone. The same report (Stewart, 1959, p. 23) also included in the Tampa Formation a "variegated (blue-gray or blue-green and cream) silty sandy clay" which was thought to overlie the limestone unit of the Tampa.
Figures 6 and 7 are geologic sections showing the formations penetrated by wells in the Polk County area. These sections were constructed from electric and sample logs. Data for the eased sections in wells were interpreted from drillers' logs. In order to identify the Tampa Formation in Polk County, it was necessary to examine logs in southwestern Hillsborough County where the Tampa Formation is better known and well defined. The correlation of the Tampa Formation in the Polk County area is based on electric logs from Hillsborough County.
In the Hillsborough County wells, the Tampa consists of a limestone unit approximately 80-110 feet thick, and an overlying sequence of interbedded, bluish to greenish gray sandy clays with, stringers of sandy limestone and calcareous sandstone which may be weathered limestone remnants. The limestone unit overlies, and is in direct contact with, the Suwannee Limestone. The clay unit of the Tampa underlies limestones of the Hawthorn Forma-
REPORT OF INVESTIGATION No. 44
FOMYD t oo
IM:. . . . . . -t. . . . . - oo
If00
-- 00
~Oft4*i~0
Figure 6. Geologic sections along lines A-A' on Figure 5.
and B-B'. Sections located
tion. The clay unit of the Tampa is cased-off in most wells. Some of these limestone beds have been almost completely replaced by gray, dense, very hard chert in wells west of Plant City, Hillsborough County (Menke and others, 1961, figs. 51, 54). The interbedded limestones and clays of the upper unit of the Tampa in Hillsborough County appear to thin up-dip and merge with the limestone unit. These units, along with very similar units of the overlying Hawthorn Formation, appear to have been deposited in a shallow littoral marine environment suggestive of oscillatory stages.
The Tampa is readily traced across Hillsborough County and into Polk County, and it is evident that the individual beds of this
tO VS
N~W5I0N
-.to
t0
too
i
1 00
300 .
too
-D to-
A .
F '-"
A,
FLORIDA GEOLOGICAL SURVEY
5 "" ( INGLIS
AVON
c'
S--200 ITS -100
- SEA
- LEVEL
-100
- 200 - 300 -400
0 1 2 3 4 5 miles
0
400
SLEVEL
z
Soo--2
. 400Figure Figure 5.
0
Figure .5.
SuWANNEE LIMESTONE
RIVER
CRYSTAL
ING IS -AVON PARK
9-4. -4u' iles
7. Geologic sections along lines C-C' and D-D'. Sections located o
200 to10 SEA
LEVEL 100, 200
300 400
-200 100 SEA
LEVEL 100 200 300 400 500
600 706
REPORT OF INVESTIGATION No. 44
formation become thinner northward. This thinning is probably 1ue to deposition rather than to removal by erosion. In eastern fillsborough and western Polk County the Tampa changes up-dip,
a predominantly limestone sequence to a predominantly clay sequence, and becomes the well-known "blue-clay" of local (Irillers, the 50 feet of greenish-gray sandy clay of Carr and Alverson (1959, p. 2-5), and the variegated sandy clay of Stewart (op. cit.). Possibly this clay is also related or identical to the 49 residual mantle of green calcareous clay" of Cathcart and McGreevy (1959, p. 228), and to the "clay unit" of the Tampa Limestone as described by Ketner and McGreevy (1959, p. 64).
The electric logs available do not indicate any significant change in character in the rocks above the blue clay of the Tampa, and it is believed that in Polk County these generally constitute only the Hawthorn Formation.
To summarize, in Polk County the Tampa Formation is generally composed of a bluish- to greenish-gray, calcareous, locally phosphoritic, sandy, shaley clay that contains lenses, fragments, and occasional thin beds of white to gray sandy limestone. The blue clay unit of the Tampa was found to be more extensive than stated by Carr and Alverson (1959, p. 25). This unit underlies the limestone members of the Hawthorn Formation in all but local areas along the northern edge of that formation, and east of the Lake Wales ridge.
The Tampa Formation ranges in thickness from about 10 feet in well 805-155-2 to about 80 feet in well 752-150-1, although possibly even greater thicknesses exist.
The blue clay in the Tampa Formation is important in the hydrology of the area because it is the lower confining bed of one artesian aquifer and the upper confining bed of another.
The interpretations of the Tampa Formation in the present investigation tend to agree with those of Carr and Alverson (1959, p. 21), postulating the existence of Puri's (1953b, p. 19-21) Chattahoochee faces of the Tampa stage of the Miocene Series in peninsular Florida.
HAWTHORN FORMATION
In Polk County the Hawthorn Formation consists of massive, interbedded sandy limestones and sandy clays which are not individually distinctive. The clays are soft, sandy, phosphatic, and usually a gray to- dark bluish- or greenish-gray. The limestone beds are light-cream to yellow or tan, very hard to soft,
FLORIDA GEOLOGICAL SURVEY
very sandy, clayey, and phosphatic. The beds are areally extensive but not really identifiable or distinguishable. Some of the beds appear to be nonfossiliferous but where the beds are fossiliferous, they contain casts and molds of large marine mollusca, silicified and phosphatized bones, and a few silicified shells. In mine pits east of Lakeland, the invertebrate fossils occurred in definite zones or beds that were traceable across the mine.
Generally the basal limestone units have been dolomitized and
-ire highly crystalline, hard, and resistant. This characteristic shows on the electric logs as a zone of very high resistivity and appears to be a more massive bed, as much as 20 feet thick. Along the northern edge of the formation the limestones are more highly weathered and earthy, and the dolomitic beds are less pronounced. Thickness of the formation differs greatly over the county, ranging from a few feet thick immediately north of the Lake Parker area to about 160 feet thick in well 747-158-3 at Bradley Junction. This is perhaps the greatest thickness in the county.
The tipper 2 to 10 feet of Hawthorn limestone were exposed occasionally in 1954-55 during mining operations in the Saddle Creek Mine just north of U.S. Highway 92 near Saddle Creek. A number of sections were measured,' described, and photographed in these mines. Mining has since terminated in this location and all of the sections described have been mined-out, buried, or flooded. The upper surface of the limestone in these pits is usuially highly eroded and overlain by 1 to 6 feet of brown, sandy, gritty clay. Locally the limestone is overlain by brown, well-indurated, clayey, sandstone which, in places, fills the irregularities on the limestone surface. In a few small areas the limestone is overlain unconformably by lenses of white to dark-green, massive, dense, blocky clay. Both the clayey sandstone and the dense clay are included in the Hawthorn Formation.
The limestones are sufficiently perm 'eable to supply water for domestic and small irrigation requirements, and locally they contain well-developed solutional cavities which enable them to yield large quantities of water.
The Hawthorn Formation overlies the Tampa Formation unconformably, and unconformably underlies sands and clays of Miocene to Recent age.
UNDIFFERENTIATED CLASTIC DEPOSITS
Overlying the limestones of the county are sands, clays, clayey sands and sandy phosphatic clays. The age of these materials ranges from middle Miocene to Recent.
REPORT OF INVESTIGATION No. 44
PHOSPHATE DEPOSITS
Over much of the area lying west of the northern unit of the 'Tinter Haven ridge and the southern part of the Lake Wales )-idge, and generally south of the latitude of Polk City, the 11awthorn Formation isoverlain by sandy clays containing pebble I)hosphate, which are in turn overlain by sandy clays and sands that have been largely leached of their original phosphate content. In part, these phosphate-bearing beds are a weathered residuum of the Hawthorn Formation, and in part constitute the Bone Valley Formation generally considered to be of Pliocene age.
North of the latitude of Polk City and west of the Lake Wales ridge, outside of the general pebble-phosphate area, the limestones tire overlain by sandy clays which have variously been described and placed in the Alachua, Tampa, and Hawthorn Formations by Vernon (1951), Cathcart and McGreevy (1959), and Ketner and McGreevy (1959), respectively. For the most part these sandy, slightly phosphatic clays are not readily identifiable in the field as to formation.
In the area generally east of Polk City, Winter Haven, and Frostproof, and south of Polk City and Haines City, the limestones are overlain by sandy, slightly phosphatic clays, and marls, or by clayey sands. In general, these materials are less dense than the phosphate-bearing clays in the western part of the county. These clays function as a confining bed for the artesian aquifers developed in the limestones of the county.
In the remaining part of the county, north and east of Haines City, the limestones are overlain by generally less clayey and more permeable marls and sands. In the north end of the Lake Wales ridge and other parts of this area, the limestones are overlain by relatively clean or only slightly clayey sands.
COARSE PLASTIC DEPOSITS
Overlying the clays in some areas of the county is a deposit of clayey, poorly- to well-indurated, quartz sand which is generally white and very clayey in its lower portion and red to purple to orange and less clayey in its upper portion. These sands are micaceous and contain stringers and beds of discoid quartzite pebbles. Bishop (1956, p. 26) describes these sediments as grading downward into the Hawthorn Formation in Highlands County to the south of Polk and as a deltaic unit of that formation. Pirkle (1957, p. 21) describes them in Alachua County as a marine deposit of probably Pleistocene age. Ketner and McGreevy (1959, p. 71-
FLOREDA GEOLOGICAL SURVEY
73) discuss this unit, and assign it to the late middle Miocene or the early late Miocene.
The unit is very thick in the Lalie Wales ridge. However, the unit appears to be absent from well 811-138-3 and others along this ridge. It is found in many lowland locations, though it is most prominent in the ridge areas. For example, remnants of the unit constitute the many low hills and knobs along Fla. Highway 33 in the area north of Polk City.
The unit is used locally as a source for small domestic water supplies and is a part of the nonartesian aquifer. It is of considerable importance to the hydrology of the county because of the high storage capacity available and resultant recharge to the underlying limestones.
The entire county is blanketed by unconsolidated quartz sands, on which the present soils have developed. These deposits have been customarily assigned to the Pleistocene, as marine terrace deposits- Recently, however, Altschuler and Young (1960, p. 202203) have established that the surface sands in the Lakeland Ridge and the phosphate-mining area of west-central Polk County are "mainly an insoluble residue of lateritic, alteration of the Bone Valley formation, and not a transgressive Pleistocene deposit." The observed lack of marine terraces, shorelines, or related topographic features at supposed terrace elevations in this part of the county strongly supports these findings.
Some terraces do exist in the eastern part of the county. These are best developed and preserved on the east Rank of the Lake Wales ridge, south and east of the city of Lake Wales.
STRUCTURE
The rocks in Polk County dip at low angles and thicken'to the southeast, south, and southwest, from the north-central part of the county around the southern end of the Ocala uplift. This broad dome, or regional anticline, is developed- in the Tertiary formations of northern and central Florida, and it has been mapped and discussed in considerable detail by Vernon (1951, p. 47-58, and plate 2). -The Ocala uplift is an elongate dome whose long axis trends
-northwest-southeast on an approximate line from Cross City, Dixie County, to Haines City in- northeastern Polk County. According to Vernon (1951, p. 53) the structurally highest point on the crest of the uplift is in eastern Citrus and Levy counties.
REPORT OF INVESTIGATION No. 44
Vernon's. structure map of the Inglis Member (now Formation) (1951, pl. 2) shows this high point to be outcrops of the Avon Park Limestone at altitudes of approximately 50 feet above sea ;evel.
Prior to the work of Vernon (1951, p. 47-52), fracturing and faulting of the rocks in Florida had not been recognized. He attributes the development of these features to the compressive forces, and the relief of tensional stresses, associated with the formation of the Ocala uplift during the late Tertiary. Vernon states (op. cit., p. 50) "-The poorly consolidated sediments-composing Tertiary rocks of Florida favor adjustments to strain by step fracturing rather than by bending.
Because the tensional and shearing stresses would be greatest over the parched area of the Ocala uplift fracturing developed by them would tend to occur in groups along the axis of the fold and to indicate the direction of greatest stress and of the elongation of the arch. If these joints are tensional they would tend to die out with depth because stretching is greatest toward the outside and least toward the inside. Available geologic data indicate that only tensional fractures are present in the area and that these are shallow."
The present investigation shows that the crest of the Ocala uplift in north-central Polk County is within a few feet of being as structurally and physically high as the crest in Citrus and Levy counties. Figure 8 is a map of the geologic structure in Polk County, shown as contours on the top of the Inglis Formation. The contact of the Inglis Formation and the overlying Williston Formation is conformable and hence represents an un-eroded horizon which is suitable for structural studies. Structural relationships are also shown by the geo logic cross-sections -in figures
6 and 7.
The configuration of the Inglis surface is the result of (1) the highly irregular surface of the underlying Avon Park Limestone, because the Inglis is relatively thin and did not fill in preexisting irregularities, (2) erosion of the -overlying rocks down to the surface of the Inglis, and (3) faulting due to uplift, after the Inglis was deposited. The northwest-southeast lineation, and the less prominent northeast-southwest lineation in the county align with the structural trends established by Vernon (1951, pl. 2). These features are the result of deep erosion of the Avon Park Limestone prior to deposition of the Inglis Formation. The parallelism of the hills and valleys strongly suggests that
50 FLORIDA GEtOLOGICAL SURVEY
r T t t ~ .
.~~ .~ iLt r L:
(33
I ' * ~I7w
Fla I" Y k
Figure 8. Structure-contour map on top of the Inglis Formation.
this erosion was controlled by fractures which parallel the axis of the Ocala uplift. The work of Vernon (1951, pl. 2) suggests that many of such fractures may be faults developed parallel to the crest of the uplift. These faults are the parallel, step-type faults. The vertical displacement along most faults is 60 feet or less. Irregularities in the structure contours in figure 8 suggests that numerous fractures and faults of small vertical displacement exist in the county, but the available geologic control is inadequate to define them.
During this investigation faults were observed in limestone of the Hawthorn Formation at mine pit exposures in the Lakeland area. Two of these faults, mentioned by Stewart (1959, p. 24), are located 0.15 miles north of U.S. Highway 92 and 0.45 miles west of Saddle Creek (fig. 2). The maximum vertical displacement of beds in one fault zone is 1 foot. Four separate fractures occur in this zone, which is the site of a -solutional
REPORT OF INVESTIGATION No. 44
ct.vern from which a spring is flowing. A second fault zone is located about 150 feet to the east and the vertical displacement along this fault is 6 feet. A spring also flows from a cavern developed in this fault, but the flow is at water level in the ditch and is less spectacular than in the first zone described. Normally water levels in the Hawthorn Formation are about 20 feet above the top of the limestone in the vicinity of the faults. However, water levels were temporarily lowered by continuous pumping from this excavation for mine water supplies, and to keep the active pits dry.
Another fault was observed in this area, approximately 1,000 feet southwest of the faults described above. The fault (zone?) strikes N30W, with approximate dip of 80ONE. The southwest side of this fault was downtown approximately 6 feet. The fault appeared to be a reverse fault, both from the apparent dip of the fault plane into the upthrown block and the slight dragging of beds on opposite sides of the fault.
The existence of the faults observed in mine workings could not be detected in the subsurface except by a long line of test holes spaced a few feet apart- and then only if the beds contained identifiable distinct lithic or faunal zones which could be used for correlation across the faults. The exposures in mine pits conclusively establish the existence of such faults and their relationship to the occurrence of solutional caverns and the occurrence and movement of ground water.
HISTORY OF STRUCTURAL MOVEMENTS
Vernon (1951, p. 62) states that the movements which formed the Ocala uplift are post-Oligocene and pre-Miocene in age. He also indicates that some structural movements may have continued irregularly throughout later epochs. One of the criteria that Vernon used for dating the uplift was an apparent lack of Miocene sediments over the structural high. However, Cathcart and McGreevy, Ketner and McGreevy, and Carr and Alverson (all 1959) each report the presence of Miocene sediments over the crest of the uplift. Carr and Alverson (1959, P. 66) indicate a late Oligocene time for the inception of the uplift, with renewed movement along a major fault on its crest in Polk County at the close of Tampa time.
Several lines of evidence collected in the present investigation strongly suggest that the Ocala uplift started prior to the deposition of the rocks of the Ocala Group:
FLORIDA GEOLOGICAL SURVEY
(1) Pronounced thickening of the Inglis and Williston Fo>,, mations in present structural lows. This strongly indicates that the faulting was recurrent through much of Eocene time. Sonie of the structural lows are probably downthrown fault blocks.
(2) Pronounced thinning of the Inglis and Williston Formations over present structural highs, and particularly over the crest of the uplift in the north-central part of the county.
(3) In a number of places all of the individual beds or units of the C"rystal River Formation and the Suwannee Limestone thin markedly over structural highs and thicken in lows. This change in thickness is particularly true in the Hilisborough County and western Polk County and in northern Polk County. Such thinning and thickening is depositional rather than erosional.
Thus, it is believed that some areas which are presently structural highs associated with the Ocala uplift were also structural highs during deposition of the Ocala Group and later rocks, and that movements which produced the Ocala uplift as presently known had their beginnings during the Eocene. The data also indicate that -some movement occurred as late as Miocene time.
SOLUTION FEATURES
The limestones of Polk County contain many inter-connected openings, ranging from a fraction of ain inch to many feet in size, which are the result of solutional removal of the limestone by circulating ground waters. Small cavities have been observed in pieces of limestone that were recovered during well drilling fromn depths greater than 1,300 feet below land surface. Many large cavities, ranging from 1 to 40 feet or more in height, have been reportedly by local well drillers. Such openings greatly increase the water-transmitting ability of the rocks and hence the yield of wells. Knowledge of these solutional features, therefore, is Considered essential to the understanding of the hydrology and geology of the limestone aquifers in the county, and in the remainder of the state as well.
Limestone (calcium carbonate) is slightly soluble in pure water. However, water which contains a small amount of acid will dissolve limestone much more readily. Rain reaching land surfac. has absorbed carbon dioxide from the atmosphere, and the ga:; and water combine to form carbonic acid. During infiltration o.: the surface and percolation downward through the soils the water
REPORT OF INVESTIGATION No. 44
'i ill absorb and combine with additional quantities of carbon C(oxide from the soil. When the weak acid is in contact with 1 mnestone for a long period of time, very large amounts of the i ,)Ck will be dissolved. Many factors influence the amount and yate of solution, but two of the most important ones appear to be the amount of contact area and the length of time in which the water and limestone are in contact.
The solution of limestone by circulating water is greatly facilitated by, and localized in, fractures, joints, and bedding planes in the rock because water moves more freely through these relatively large, continuous openings than it does through the original or primary pore spaces of the rock. Solution and removal of limestone is, therefore, more effective and rapid along the fractures, joints, and bedding planes and is most effective at their intersections. An extreme development of solutional features along fractures occurs along fault zones in limestones of the Hawthorn Formation in the Saddle Creek Mine, east of Lakeland. These faults have only I to 6 feet of vertical displacement. One cavern developed along the fault zones measured 8 feet deep, and another measured 3 feet deep. These are minimum depths, because accurate measurements could not be made. Both caverns were 2 to 4 feet wide and were confined to the fault zone. The limestone elsewhere in the exposure is relatively devoid of smaller solutional tubes, cavities, and honeycomb as noted in the older limestones in table 4. Though fractures provide the avenue of easiest and greatest solutional excavation, and hence the largest caverns, the primary porosity in most of the limestones of this area is sufficiently high to permit some passage of water in response to natural gravity flow.
In inter-fracture areas, water moves much more slowly; hence, the quantity passing a given point per unit of time is less, and solutional excavation is much slower. Small primary pore spaces slowly enlarge and coalesce and the limestone develops a finetextured, honeycomb or spongiform appearance. This type of solution is speeded by the removal of the shells and tests of marine invertebrates, particularly those of large mollusca and echinoids, leaving relatively large open pores. Honeycomb development was :dso observed on many random pieces of rock recovered during drilling operations in other wells.
With the continual movement of ground water and solution, ,extensive honeycomb and tubular networks develop simultaneously with major cavern development along fractures, where the rate
TAzLE 4. Solutional features penetrated by wells in Polk County (e, estimated)
Altitude of Apgareas
USS FS Altitude of bltomude of height Probable
well well lad in feet feature in of feature Geoloiec
number number above rol feet below Inu in fees Type of feature Unit Source of dala Reimarks
739-121.4 741-139-2
741-140-1 741,141-1
742-129-1 743-157-1
744-148-1 745147-1
745-148-3
746- 58-1 745- 58 745- 59-2 746- 48-1 746- 48-1 748. 50-1 747- 14-1 747- 33-2 747- 87-1
747- 42-2
747-143-1
747-144-2 747-1443 747-153-2
W-668
- 'S W-981
W-4123
W-2304
Wgi-M W-1 726 W-978 W-1110
W-912 Wgi-348 Wg*348 Wi-1008
748-131-1 Wgi-1012 748-144-2 Wi-342 748-145-1 W-2139 748-148-1 W-1050 748-148-4 W-995
748-145 W-6839
749-144-1 Wgi-364 749-145-1 Wgi-471 749-145-2 Wi-378
62 149
147 132
104
140 180
129
138
163 137 1600
223' 149 153 61
128 147
160
182
216
206 167
243 212e 210 110 110
115
232" 217 231
733
782
+71 273
746
100
+2 +114 +108
-76 689 705
605
667
691 677
206 500 812 035
640 643 6O4
649 13 639
646 1,060
632 612 277
618 630 637 6483 669 680 684
760 10
|Honeycomb Cavern
do do
Cavern fill Cavern
do do
do do do do
Porous zone
do
Cavern
do do
Porous zone
do do
Cavern
Porous zone Cavern
do do
Cavern fill Porous zone
do
Cavern fill Cavern
do
Porous sone Cavern
do
Honeycomb Cavern
do do
Porous zone
Cavern fill Honeycomb
Avon Park
do
IHawthorn
Crystal River Avon Park Hawthorn
do
do do
Tampa Avon Park
do do
Tampa Avon Park
do do
Hawthorn Avon Park
do do
Avon Park
do do do
Suwannee Avon Park
do
Lake City? Avon Park
do
Crystal River Avon .?"rk
fo
to
co
to
Avon -ark Hawthorn
FOS geologic log Owner
Driller Owner
Driller's log Owner Driller
Owner
do
Driller's log
do do
Electric log Driller Driller's log
do
Driller Electric log Driller's log
do
Owner
Driller's log
co
Co
to
Co0
to
co Co
Electric log Driller's log
to
co to c.o
Driller's log
do
Additional small cavities reported above this
Honeycomb? "Loas of cuttings"
Honeycomb? "Lme with crevices" "Brown lime with crevices" Size not given, depth to top of
cavern
"Brown lime with crevices"
"Break"
"Big water" "Green shale and sand" "Loss of cuttings" "Loss of enuttings-water" "Brown lime and sand" "Break"
Occurs in interval 815-822 ft Honeycomb?
"Brown lime rock crevices" "Lime shells and sand"
749-149-1
749-1-1 749-159-1 750-142-3
750-145-1 750-148-1
750-151-4 750-158-1
751-140-1
761-141-1 '761- 45-1 '751- 45-2 751- 45751- 46-2 '751- 48-1 751- 55-2 752- 84
752- 41-3 762- 42-1 752- 42-7
752-1445-3
752-1454 752-146752-146-4
752-150-1 762-201-2
752-201-3
753-133-1
753-134-2 753-143-1 753-145-6
7.3-149-2 753-149-3 753-150-3
Wgi-1044
Wgi-344
Wgi-485 W-41
W-1395
Wgi-M3
W-928 W-974 Wgi-363 Wgi-352 W-1006
W-2&6 W-2M Wgi-1019 W-4189
W-1111
Wgi-355
Wgi-359 Wgi-460
W-1 113
Wgi-1020
Wgi-1021
Wgi-1023
W-500
W-2151 Wgi-167 W-2425 Wgi-371 W-945
126
160e 1550 1760
190 85
136 151 1350
163 176
2120 1860 171 113 183
201 144 171 159
176 1670 209
196
1250
120e
1200
183
242 151 162 101
1220 116
539
243 292 605
44 522 524
407 665
2,467
4,455
641
4
889 693
487 608 815
507
485 516
233 572
384 551 665
615 53
456
507
524
77 520
591
734 565
620 177
626 617 583 6M9
448 342
329
5o
3
1
5 15
3
2
2 24
62
37
2
5 68
4
8
7
22 11 46 i8
16 11
5
107 112 71 16 90 50
8 68
1
4 35
5
43 12 32
20 20 18 is
do
Porous zone
do
Cavern Honeycomb Cavern Groavel
Cavern Cavern fill
Honeycomb Porous zone
Cavern
do
Porous zone Cavern
do do
Porous zone
do
Honeycomb Cavern
do
Cavern fill
do
Cavern Honeycomb Porous zone
do
Honeycomb Cavern fill
do
Porous zone
do do
Cavern
do
Porous zone
Cavern Cavern fill
Porous zone Cavern fill
do
Porcus zone Honeycomb Cavern fill
do
Avon Park I-lawthorn
do
Avon Park Hawthorn Avon Park
do do do
Oldsmar Lawson
(Cretaceous) Avon Park Hawthorn Avon ?ark
Co r 0
C o
co
Avon 7ark
C-o C-0
Williston Avon Park Williston Avon Park
do do
Suwannee Avon Park
do do
Tampa Avon Park
do do do
do
Crystal River
Avon Park Avon Park
do do do
Inglis
Williston
do Electric log
do Driller's log Owner Driller's log
do do do
do do
do Owner Driller's log
do do do do do Driller's log
do do do do Owner Driller's log
do
do do do do do
Electric log Driller's log
do do do
do do
do Driller's log
do
do do do
do
Cavity fill?
"Cave-in"
"Water, sand, heavy flow of
water"
"Porous limestone with sand
lenses" (cavity fill)
"Brown lime with cavities"
"Crevices" "Crevices"
"Sand"; at top of Inglis? "Clay with silt" At top of Inglis?
"Brown lime-crevices" "Brown lime with crevices" At top of formation? "Water sand" "Shells and water sand" "Hard brown lime, crevices in
lower section"
At top of Suwannee? "Hard lime rock with small
openings"
"Vicksburg llme, small opening. no returns"
Well 25 ft east of well above "Sand coming into well"; at
top of Williston? "Full of crevices" "Sand"
"Water, sand, and gravel" "No cuttings returned"
"Brown sand and soft lime
rock". at top of formation? "Lime rock and sand"
TABL 4. Solutional features penetrated by wells in Polk County (Continued)
(e, estimated)
Altitude of Aplarent
USGS FOS Altitude of bottom of eigt robable
well well U d in feet feature in of feature (reologie
number number labve sa~ld feet below inil in feet Type of feature Coilt ollmrr of data Remaarks
763-150-3 W-304 753-151-2 W-0S 754-144-I Wgi-353
74-1502
751-52-2 W-1801
754-152-3 W-1802 ?74-1- W-110
7 5-1- W-2098
758430-1
756-13-34
756-150-1 767-133-1 757-133-2
Wgi-1031 Wx-30 WOi-300
767-140-1 W-952 757-152-1 W-1441
757-153-2
757-1534 757-154-3 767-154-5 '758-139-1
758-144-1 758-152-3 758-153-1
758-1534
758-155-2
759-134-1
Wgi-340 W-2241 Wgi-47 Wgi-404
W-1864 Wgi-365 Wgi 41
Wga-338 Wgi341
1240
122
147
140 136
200
95' 118
215 185
142
122 117
128
122 167'
234
142 145 1200 123
130
128
258
204
018
510 53o
+23
928 009 039
502
235
82 596
545 233
332
540 99
275
321
457 31
272
473 552 532
470 480 390 237
465 527
124 225 422
553
491
7
4 33
2
7
8
50
2
10
5
2
G
25 30
85
2
2
7
8
2
2 40
8
4
110 40+
2
2 79
7
6
8 11
Porous zone Cavern Porous zone
Cavern IIoneycormb
do
Porous zone
Cavern
Cavern and cavern fill Cavern fill Cavern
do do
Cavern fill
do
Cavern Porous zone
do do do
do
Cavern
do do do do
Cavern ill Cavern
do do
Porous zone
Cavern
do do
Porous zone Cavern
Avon Park
do do
Taiia Avon Park
do do
Suwaunce
Avon Park
Inglis
Crystal River Avon Park
do
Inglis
Avon Park Avon Park Cry-stal River Avon Park
do do
Suwannee Crystal River Avon Park
do do do
do do
Inglis Avon Park
do
Suwannee Williston Avon Park
do do
Driller Driller's log
do do
do
do
lo do
do do
do
do Driller's log Electric log
do do do do Driller Driller's log
do do Tenant Driller's log Driller Driller's log
do do
do do do do do1
"No cuttings returned"
"Brown lime with open crevices"
At top of Lake City?
"Changed by solution action.
likely cavernous"
Exacet depth not reported.
cavern occurs in the internal
from 119 to 158 ft
"Water, sand. gravel, and
small cavern'
"Sand"; at top of Avon Park?
"Coral and white sand"; at
top of Avon Park? "Coral and white sand"
Reported by a local driller "Cavern, gravel-filled"
Present when drilled "Lime and water sand" Full depth not measured "Sand'
"Brown lime. rock with crevices"
At top of Crystal River? SAt top of 1nlis?
"Crevices-big water" Apparent diameter not, given
759-143-2 7I9-156-1 759-159-1 759-200-1
W-1445 W-2153 W-2129 W-2954
759-201-1 W-632 759-201-2 W-633 800-135-1 Wgi-801 800-1533 W-724 800-156-2
800-156-8
800-157-1 W-2015
800-159-1
801-138-2 801-139-2 801-139-8 801-146-1
801-200-38
801-201-3
802-134-1 802-136-2
802-136-8
802-148-1 802-143-2
802-143-4 802-149-4
802-150802-151-19
802-152-10 802-154-2
W-3420
W-4493 Wgi-1042
Core 2
Wgi-1043 W-3305 W-3306 W-3307 W-36033
W-3422
136
155
143 136e
132 135 170 119 139 132
204
146 128 139 149e
150e 1350
134 130 193 '204
147 144 145
130
119
+21 110
1420
511
521 526
552
556 +86
+76 +60 255 530 535 326
341
611 581 138 516 568
+13
52
392 281 20
810 320
412 597 26
412 417 574 65 81
435 +10 672
497 433
820
-+0
5
+45
?
37
7
37
7
314
4
3
2
2 10
5
6
2 15
20 20
50
12
11
4
5 10
?
5
10
7
2 10 55
3
2
6
14
7
4 11
12
8
5
5
5
8
?
Cavern and sand Cavern-no sand Porous zone
Cavern
Porous zone Cavern
do do do
Porous zone Cavern
do
do
Cavern fill Porous zone
do
Cavern fill Honeycomb? Cavern? Cavern fill
Cavern Cavern fill Porous zone Cavern
Cavern Cavern fill Cavern
do
Porous zone Cavern
do do do
Cavern fill Cavern
do
Porous zone
do
do
Cavern and fill
Porous zone
do do
Cavern
do do
Avon Park
di
do
Hawthorn
do Tamps Inglis
Avon Park
do do
do do do
Crystal River Avon Park
do
Suwannee
Hawthorn Avon Park
do
Suwannee
Avon Park
do do do
Suwannee Avon Park
do do
Crystal River
do
Avon Park Suwannee
Avon Park
do do
do
Tampas Suwannee Hawthorn
?
do do Driller's log
do
do
do do di)
Electric log Driller's log
do do
do do Driller
do Driller's log
do
Observation
Driller's log Driller Driller's log Driller
Observation Driller's log
do do Driller Local driller Driller
do Driller's log
Co
to .o
C-0 Co Co c.o
Co
do
Electric log
do
Observation Owner
"Three or four 1- and 2-ioot
cavities"
Probably not bottom of well
-depth not given in log "No cuttings returned"
At top of Suwannee? At top of Avon Park? "Creices-hard rock"
"Sand in bottom of this
stream"
"Brown rock with some sand" "No cut tingsreturned" "Lost circulation" "Sand"
"Water"
Dark organic clay, with small
clusters of satin-spar
"Sand and gravel" "Lost cuttings" Top of cavity-depth not reported
At top of formation? "Sand and mud"
"No cuttings returned"
"Blue mud"
"Breask"; at top of formation? "No cuttings returned" "Series of caverns" "Several openings with water"; at top of formation? "Opening of mud and odor of
gas"; at top of Lake City? At top of Suwannee? At top of formation? Loss of cuttings Depth to feature and height Snot given,probably in bottom of well
TAsLI 4, Solutional features penetrated by wells (e, estimated)
in Polk County (Continued)
Altitude of Appaorent
USOB FOS Altitude of bottom of height Probable
well well lad in fees feature In of feature Geologic
number number above nal feet below nusl in feet Type of feature Unit Source of data Remarks
am-M_ I-qao &- 1.r 4 do Suwannee Driller
802-157-7 802-157-16
802-158-1 803-134-1 803-138-1 803137-1
803-145-1 803-145-2
W4153 W-2767 W-458
W-1416
W-3444 W-2925
803-146-2 W-2720 803-147-4 W-872
803-147-12 803-153-12
803-153-14
803-1M-24 808-153-28 808-1&5.31
803-154-43 803-25614 803-158-1
804-143-1
805-136-1
805-186-4
805-136-
Wgi-1051
W-3425 W-424 W-1800 Wg-80.5
W-24
W-4412
Wgi-105.
210 191 193 11)
174
164
1465 155
183
169
141 124' 1250 124 127 138
141 148 218
133e
175e 202 190e
+i10
40
471 523 530
459
418 298 326
7
+13
.+0
-62
476 +61 +27
67
-h-0
12 429 442
402 524
19
25
+17
92
Cavern
do do do
Cavern fill
Cavern
do
Porous sane
Cavern
do
Porous zone
do
Honeycomb
Cavern
do do
Cavern fill Cavern
do
Porous zone Cavern Porous zone Cavern fill
Cavern
Cavern fill
do
do
do
Suwannee
Avon Park
do do do
do do do
7
Hawthorn
do
Suwannee
Avon Park Hawthorn
do
Suwannee
do
Suwannee Avon Park
do
Avon Park
do
Hawthorn
Crystal River
do
do
do Owner
Driller's log
do
do
FOS Geol. log
Tenant Driller's log
do
do
do do
do do
do do Driller
Observation Driller
do Driller's log
do Driller's log FGS Geol. log
Driller's log
Owner
do
Driller's log
!
CM 00 1
At top of formation?
Depth not given, probably in
bottom ofwell
"Fine quartz sand and finely
powdered limestone" Present when drilled
::Bond$@
"Lost cutting" and "Honeycomb chunks"
Depth and size not given-probably in bottom of well
"io cuttings returned--soft .honeycomb"
"No cuttings returned" "No lawge cavities-only 4- to 6-ineh opening." Depth Intervals not reported.
"Open cavern and Loss of cuttings"
Sand-filled honeycomb
"Lost cuttings" Size not given "Occional crevice of Cavern" "Quartz pebbles, peat, porous limeone, blue clay, and pyrite"
"Sand, dry, under rock"; at top of formation? "Sand pocket"; at top of formation?
'Top of sand ocket--not drilled into'; at top of Williston?
808-148-2 W-393 808-147-34 805-149-2 W-4188 805-158-4 W4018 805-154-8 Core #1l
805-155-2 W-3766 805-166-2 W-3769 80-189-1 W-312
806-187-2 W-3207 806-137-3 W-3799 806-187-4 W-3802
806-187-5 Wgi-109
806-187-9 W-402 806-188-1 W-464 806-186-2 W-3771 807-185-1
807-154-4 W-3883 807-157-2 W4884 807-159-1 Wgi-10859 807-201-1 W-2774 808-157-1
808-200-4 Wgi-1063 809-1854-
809-147-1 W-4275
156 1550 1859
182 180
135 186 206
178
145 143
133
178 129 186 181 135
154 1756
143 1660 199 155 135
810-141-1 810-147-1
502 347 426 +48
382
399 644
664 664
+43 +56
54 +34 360
290 338 82
184 372
419 201
317
489 512 484
+41
119
417 426 +6 85
+69
506 +1
5
876
377 72 824
329
334
9
2
4 43 10 1+ 10
3
5
S
2
8
4
20
4
6 10 33
7
15
2 75
1
2
10+
14
2
6 18
1+
5
1
I
1
Cavern do
Porous zone do
do
do
Cavern fill Porous zone Cavern fill Cavern Cavern fill
Porous zone Cavern Porous zone Cavern fill Cavern Cavern fill Cavern Porous zone Cavern Porous zone
Cavern and fill
Cavern Cavern fill
do
Honeycomb
Cavern
do
Honeycomb Cavern
do
Cavern and fill
Porous zone Cavern Cavern fill Cavern
Porous zone Cavern
do do d3
Avon Park do do Suwannee
Avon Park
do do do do Suwannee Tampas Suwannee Hawthorn Avon Park Avon Park
do
Crystal River Avon Park
do do do
do
do do do
Suwannee
Crystal River Avon Park
do Suwannee
do
do
Avon Park Crystal River
do Avon Park
do do do do do
do
Driller
Driller's log "No cuttings returned"
do '!Lost ciroulation"; at top of
. formaton?
Driller's log "Lost.all circulation"; at top
and observation of formation. Driller's log Do
do "Sand poket"
do "Lost all circulation"
do "Sand coming into hole"
Observation
do At top of formation.
Driller's log 'Honeycomb"
do
do "Water and sand"
Driller's log "Soft sand"
c.o
Lo "Sand"
cLo
c o "Creviced brown lime"
to
co "Cuttings pae off into subsurface streams" do "Cavity with coarse brown
sand"
do
FGS GeoL log "Sand"
do "Sand with some limestone
fragments"
Observation "6- to 8-inch cavitiee-88 to
95 feet"
Driller
Driller's log
Driller
do
Driller's log Depth to cavity not given-probably at bottom of well Driller 10-ft cavern, then into clean
sand
Driller's log "No cuttings returned"
Driller At top of formation?
do "Sand"
Observation (Dolomite pebbles up to 1inch diameter recovered from floor of cavern) do "Honeycomb"
Driller's log At top of formation?
do do do
C1t -
TABL.e 4. Solutiunal features penetrated by wells (e, estimated)
In Polk County (Continued)
Altitude of Aptreas
U180 FOR Altitude of bottom of Probable
well well Iad in fees feature in of feature Gelolie
number number above mal fest below mel in fees Type f feature Unit Source of dta Remarks
810-147-1
810-155-1 W-386 811-188-3 W-4199 811-149-1 25 813-189-1 Wl-1068s
813439-2 813-149-1
813-201-1
W-548
W-5352
814-138-1
814-139-1
815-139-1 Wgi-009 815-157-1 W-3810 815-157-2 W-8839
816-146-1
817-139-2 817-150-1
818-140-1 818-161-2
344 349
372 61
305 315
447 347 469
49
95 105 130
140 118
361 3941
14 20
21 31
36
41
406
17
261
264 276
94 287
216 602 602 +34
W-4680
Wgi-1073 w-i-1074
3
2
2 60
5 27
27
5 10
10
91
3)
13 1I
s
1.
1
do do do
Porous zone
do
Cavern Cavern fill Porous zone Cavern fill
do do do do do
Porous zone Honeycomb Cavern
do do
Cavern fill Porous zone Cavern Porous sone Cavern Porous zone Cavern
do
Honeycomb Cavern fill Cavern Cavern fill
Cavern
do
Cavern fill
Cavern Cavern
Cavern
do do do
Suwannee Crystal River Avon Park
co
t'o
co C.0 do
Williston Inglis Avon Park
do
do do do
Crystal River Williston
do Inli U
do do do do
do
do
Avon Park
do do
Avon Park
do do do do
Crystal River
do
do
do
Elctrie log
do Owner
do
Drillers log Driller
do do do
Observation
do
Observation
do
do do Driller Driller's log
do
Observation
eo
eo to
to
to to Co
Driller
Observation
do do
Driller's log
do do Driller
do Owner
"Bad"
"No cutiup returned" "and bed'
Do
Do; at top of Lake City? Do
nart sand cavity ll
No Cutting returned Few cuttings returned
Limestone and sand beds "No cuttings returned"
"No cuttings recovered"
Do
Small cavities With quarts sand
Sand avityfll prevents further drilling
Size not reported; at top of
formation?
No cuttings recovered Quarts sand-preventu drilling
"Sand"
At top of Wjoillisn?
818-155-2 Wgi-10io
Filled caverns, Cavern Cavern fill
Ingis
do do
do do
Dnller do
do
- top of formation? "Sand and muck"
N
'U 0P
IL-oMA GEoLoGicAL SuRvEy
of development is much faster. Tributary flow thus becomes established in an elementary pattern, controlled by fractures, and the cavern system is enlarged and extended with time, much as surface drainage systems are developed. This process progressively increases the water-transmitting ability of the limestones.
As the solutional caverns become larger the roofs, in some instances, may slowly become incapable of supporting the overlying materials and eventually collapse. If the collapse extends upward to land surface, a sinkhole is formed.
Obviously cavern systems functioning as ground-water conduits or drainage systems must have a terminus, or point of discharge. In artesian aquifers, such as those in this-'area (Stewart, 1959), the cavern systems will not discharge at land surface unless land surface is below the piezometric (pressurehead) surface of the aquifer concerned. In such discharge areas, concentrated flow at lapd surface, as artesian springs, will occur where the confining beds are breached. It is likely that most of the discharge of cavern systems of Polk County occurs through the multitude of artesian springs in Hillsborough and other adjacent counties to the south and southwest. The only significant artesian spring in Polk County is Kis4engen Spring, southeast of Bartow. The so-called "Ft. Meade Spring," just east of the town of Ft. Meade, is actually a man-made pool fed by a flowing artesian well.
Diffuse discharge at a low rate probably occurs as general upward leakage through confining beds in areas where the artesian head is great, and confining beds are not visibly breached. In Polk County such an area probably exists over much of the valley floor of the Kissimmee River below Lake Kissimmee, and of the Saddle Creek-Peace River system below U.S. Highway 92, east of Lakeland.
CAVITIES
During this investigation data was compiled on open-cavities, honeycomb zones, and zones in which drill cuttings were lost at depth in the limestones of the county. Beds of unconsolidated quartz sand and similar sands encountered in the bottoms of open caverns are all interpreted as cavity fillings, because such deposits are not known as regular primary sedimentary deposits in the rocks of Tertiary age in central Florida. Such deposits, along with the other solutional features, are tabulated and presented in table 4. The locations of these wells and the altitude of the base of the deepest feature encountered are shown in figure 9.
REPORT OF INVESTIGATION No. 44
, .-.-._ .T F ,,,E,,C_ & *,
. _ - .- \.,u E . .
/6 ' O POLK COUNTY , j
A,5aEE CO' PRDEE ?C 0U N TY J HG ANS COUNTY ~U8 05" ~ ro 5" '" 2' 20r
Figure 9. Map showing the location of wells penetrating solution features in the limestones.
The preponderance of solutional features in the harder, more crystalline, Avon Park Limestone is evident, and these total 65 percent of all solutional features recorded. Many of the wells shown in table 4 do not penetrate the Williston and Inglis Formations and the Avon Park. Thus the number of solutional features in the Avon Park may actually exceed the proportion indicated. The table includes data from 190 wells and it records 274 separate features. It is believed that if detailed drilling logs were available from all Wells in the county, the actual number of wells which penetrate solutional features would be vastly more than the wells now tabulated. However, such logs are available for less than 400 of the more than 1,300 wells inventoried during this investigation (Stewart, 1963, table 1).
A number of general observations may be made from figure 9: 1. Multiple zones of cavern development, at different altitudes, exist in the same local area, as in the area west of Lake Hancock.
FLORIDA GEOLOGICAL SURVEY
2. Locally the data show a definite correlation of altitude of cavern zones, as in the area immediately west of Lake Buffum. at -650 msl, and in the area southwest of Lake Parker at -550 msl. These zones may be part of an integrated cavern system.
3. Four wells (750-148-1, 754-152-2, 747-137-1, and 741-139-2) penetrated cavern systems or solutional features at depths in excess of -900 ms]; one of these (750-148-1) penetrated a honeycomb zone at -4,455 msl.
4. Numerous solutional features exist at altitudes above msl, particularly in northeastern Polk County.
5. Caverns have developed in areas where the limestone is deeply buried, as in the southwestern part of the county.'
6. In general, the caverns of the Lake Wales ridge are at shallower depths below sea level than those of other parts of the county in the same latitude.
A comparison of figures 4, 5, and 9 suggests that the general distribution of wells known to penetrate solutional features is more closely related to the distribution of well data, than to the geology of the area. Data are very sparse for southeastern Polk, because few wells have been drilled in this area. As this is an area of general artesian flow and upward leakage, it may be assumed that large caverns such as those known and reported in Hillsborough County may exist in greater numbers than the map indicates.
In general, there appears to be an increase in depth below both land surface and msl of the deepest local cavern zones with increasing distance from the north-central part of the county, following the slope of the piezometric surface and formational dip.
The study of the cores from wells 805-154-8 and 801-200-3 produced detailed data on the solution features of the underlying limestones. The cores show a concentration of solutional features in the Avon Park Limestone. A series of cavern developments and subsequent collapse and filling in the Avon Park Limestone, and a few features in the underlying Lake City Limestone, occurred prior to doloinitization of these formations. These caverns. show, in many cases, a second stage of solutional excavation and fill which occurred after dolomitization. In several instances. these solutional features strongly suggest a third stage of solutional excavation, now occurring in the second stage fill. Abstracted logs of these, two test holes and of well 815-157-2. presented earlier indicate the extent of solutional features observed.
REPORT OF INVESTIGATION No. 44
In addition to this series of features, three separate caverns were penetrated in the Avon Park Limestone in well 801-200-3; these were in the intervals of 440-445 feet, 5401/,.-5471/, and 729 /L-731 X) feet, respectively. The upper cavern (440-445 feet) was underlain by quartz sand and mud fill from 445-455 feet. The middle cavern was apparently underlain by 1051/2 feet of soft mud and sand fill, and/or very soft honeycomb limestone, because casing was set through this interval without drilling.
Limestone-filled solutional cavities were also found in the upper surface of the Suwannee Limestone in well 801-200-3. After development of the solutional features, the surface of the Suwannee was replaced by chert. Limestone of Miocene age [Tampa (?) Formation] which contained numerous Sorites sp. was then deposited and' filled the preserved solutional features.
No significant solutional features, other than some fine honeycomb, were observed in the soft, chalky, highly calcareous Suwannee Limestone or Crystal River Formation in wells 801-200-3 and 805-154-8.
SINKHOLES
Undoubtedly the most spectacular surficial evidence of solutional activity is the formation of collapse sinkholes. Thirty active sinks were recorded in west-central Florida from 1953 to 1960. Nineteen of these have occurred in Polk County, including those referred to by Stewart (1959, p. 13-16), and all of these are listed in table 5. Location of these sinkholes are shown in figure 10.
Because of the relatively small diameter and observable depth, all of these sinks are believed to have had their origin in the upper-most limestone of the area concerned. Study of the data in table 5 and the piezometric, structural, and geologic maps presented elsewhere in this report indicate a wide variety of local conditions at the different sites. None of the sinks occurred on local topographic highs. Land surface at the sites did not exceed 150 feet above sea level. Land surface at 13 sites is 70 feet or less above limestone; at 5 sites the depth to limestone ranged from 100 to 225 feet. Only six sites were not closely associated with, or adjacent to, pre-existing sinkhole areas. Figure 11 shows two of the sinkholes developed recently in the county.
Between -1953 and 1960, 11 sinks were formed in adjacent Hillsborough, Pasco, and Hernando counties, and probably others occurred elsewhere. Though most of these sinks have been of
FLORIDA GEOLOGICAL SURVEY,
EXPLANATION
0to
Sinkhole
Location number refers to number in Table 5.
sPolk C-ly
!4 I 12
iLAAELAP4O
9
I
! TwSS
1C1venpo t INHaires City
3 AuburidoloI Eoton Park
0 7
ONARTOW
1,10
mforht~aven IDu
138
5
lluraol 0
D6 ift Meode
ndee4
ELake Wals
*Fms toroof
L.
Figure 10. Map showing location of recent sinkhole collapses.
small dimensions, their sudden appearance has caused considerable local alarm. The formation of sinkholes is a completely natural occurrence and perhaps most vividly illustrates the principal geomorphic process operating in this area. Other such collapses in the future are a certainty.
The multitude of round, closed-in basin lakes in central Florida and Polk County are widely held to be of sinkhole origin, and as such are evidence of considerable solutional activity in- the geologic past. Though many of them may have occurred prior to the historic past, they are none the less spectacular due to their size and numbers. The smaller lakes in Lakeland, such as Lakes Mirror, Wire, and Morton, are almost certainly single sinks. Because of their very circular shoreline, larger lakes, such as Hollingsworth in Lakeland, Ariana in Auburndale, and Howard in the City of Winter Haven, and scores of others in the county, are also believed to be single sinks. A number of large lakes, with
TABLE 5. Records
of the occurrence of recent sinkholes in Polk County
(Reported data shown by "r")
Location Diameter Depth in Altitude in
Number Date of Mode of in feet at feet below feet above Quarter Township Range Nearest
(on fig. 13) collapse occurrence land surface land surface land surface section Section south east town
1 1953-64 (4) Instant 8-12 12-40 r 1154- SE 6 30 25 In Bartow
NE 7
2 4- -54 do 8 r 8 r 130 NW 15 28 24 Lakeland
3 9- -54 do 22 4+ 110- NW 11 28 24 Lakeland
4 5-8-55 do 30 30 136 SW 14 29 24 Highland City
5 4-756 do(40 r)
204-7-56 do +8 20 120 NE 7 30 27 West Lake Wales
(40 r
6 4- -56 do 40r 4r 175k: NW 34 30 26 Alturas
7 4-9-56 (2) 3 months 30 1-1k 126 NW 23 29 25 Bartow
2 hours 100
8 4-10-56 Instant 75 r 10 r 180;k SE 34 28 26 Winter Haven
9 7- -57 Co s0 16+ 10 NW 22 29 24 Lakeland
10 9-1G-57 C-0 8r lOr 115 NE 7 30 25 In Bartow
11 11-8-58 Co 00 r 40 r 100d1 SW 0 30 25 Bartow
12 4-17-89 Lo 5 9-10 140 SW 30 27 24 Lakeland
i1 5-5-69 C-o 70 r 40 r 130 NE 38 28 26 Winter Haven
14 5-28-60 .o 30 unknowil 140 SW 17 27 23 Kathleen
REPORT OF INVESTIGATION No. 44
Irregular or complex arcuate shorelines, such as Bonny, in Lakeiand; Gibson, near Lakeland; Crooked Lake, at Babson Park; ,ind many others, are a coalescent group of smaller sinks, or are 1nore properly referred to as valley sinks. For example, Lake Bonny-in Lakeland, at a stage about 6 feet below normal in June 1956 was shown to be formed by a group of smaller adjacent or coalescent sinks by aquatic grass and other vegetation growing around the periphery of the small sinks in the shallow water.
Many sinkhole basins contain only ephemeral lakes or ponds. Such basins range from several hundred feet in diameter and scores of feet deep to a few feet in diameter and depth. The larger, deeper sinks are profuse in the Lake Wales ridge section where the relatively porous overburden is very thick.
The original depth of the sinks (or depth to point of collapse or cavern) is generally unknown. Wells on, or near, the floors of sinkhole basins are few because well drillers have found that unconsolidated materials in such basins may extend to great depths. This requires great amounts of well casing, and frequently presents considerable difficulty in drilling, installing the casing, and developing the well. To further complicate drilling in such locations, the honeycombed, fractured, or cavernous limestone, is commonly impregnated by sands, silts and muds which reduce the yield of the wells, and require additional casing in most instances.
HYDROLOGY
Hydrology is the science that relates to water on and within the earth and in the earth's atmosphere. Water moves continually from one to another these environments, and man diverts a part of it, temporarily, for his use before releasing it back into the cycle.
A relatively small part of the rainfall runs off over the land surface because of the permeable sand cover. A larger part of the rainfall is returned to the atmosphere by evaporation from the soil, bodies of surface water, and the vegetation. Part of the rainfall infiltrates the surface and percolates downward into the soil, and much of it is held as a film on soil particles, taken up by plants, and subsequently transpired back into the atmosphere. The water in excess of these requirements percolates downward through the soil and remainder of the zone of aeration, and eventually reaches the zone of saturation to become ground water.
FLOUDA GmomcAL SuRvEy
Within the zone of saturation, water moves through the earth materials, in response to gravity, to points of discharge such as springs, lakes, streams, oceans, and wells.
The appraisal of the ground-water resources of the county is at best only an approximation, because none of the quantities involved in the various factors can be measured directly runoff and precipitation. Techniques for accurate measurement of evaporation and transpiration do not exist as yet, and even adequately detailed measurement of rainfall and runoff are seldom possible and always costly.
Because of variations in climate, and the requirements of man, it follows that the quantity of water available in an area will differ from year to year.
SURFACE WATER
STREAMS
In general, surface drainage in the county is poorly developed and is almost entirely of two types: (1) basins of interior drainage (without surface outlet), and (2) streams of very low -gradient w'L.ich, for the most part, do not occupy well-defined- valleys. In many places these streams have not cut well-defined channels. The county lies within six major drainage basins, as ordinarily defined, and these are shown in figure 2.
Approximately 15 percent of the county is drained by the Withlacoochee River which forms part of the northern boundary of the county (Heath, 1961, p. 8 and fig. 8). The river flows west into Pasco County, where it turns sharply north and empties into the Gulf of Mexico near Inglis in Levy County.
About 4 percent of the west-central part of the county west of the Lakeland ridge is in the headwaters of the Hillsborough River and about 8 percent of the southwestern part of the county (Heath, op. cit.) is in the headwaters of the Alafia River.
The area between the Lakeland and Lake Wales ridges, and south of Providence, Auburndale, Lake Alfred, and Haines City, is in the basin of the Peace River. Approximately 35 percent of Polk County lies in this river basin (Heath, op. cit.).
A narrow finger of the headwaters area of the OklawahaSt. Johns River basin extends into northeastern Polk County, along the west flank of the Lake Wales ridge, north of -,Haines City. This area (2-3 miles wide) represents 3 percent of Polk County (Heath, 1961, p. 10), and is drained by Green Swamp Run'.
-REPORT OF INVESTIGATION No. 44
The eastern 35 percent of the county -(Heath, op. cit.) is in the basin of the Kissimmee River.
Tributaries of all of these rivers are generally short, poorly defined, and few in-number. The cour se of the Withiacoochee in this county is a thickly timbered cypress river-swamp that ranges from about a hundred feet to more than a mile in width. Where the channel of the river can be defined within the swamp, it is generally less than a hundred feet wide. The Peace River has a well-defined channel between Bartow and Ft. Meade.
Table 6 shows the annual runoff in three drainage basins TABLE 6. Annual runoff by drainage basins, in inches of water over the basin
(Data supplied by Surface Water Branch, UJ.S. Geological Survey, Ocala, Florida)
Station 1954 1955 1956 1957 1958 1959
Alafia River at Lithia,
Hillsborough County 14.28 8.40 5.37 18.56 13.26 .34.42
Area: 335 sq. mi.
Peace River at Bartow,
Polk County 8.00 3.89 4.47 14.40 10.49 28.16
Area: 390 sq. mi.
Peace.River at Zolfo Springs,
Hardee County 12.21 5.63 5.42 14.63 12.10 27.52
Area: 840 sq. ini.
Kissimmee River below Lake
Kissimnmee, Polk County 10.93 4.28 2.60 9.30 9.27 20.38
-Area: 1,609 sq. mi.
during this investigation. Runoff is given in inches of water over the basin area. The stations listed here are those nearest to, or within, the .county, in the drainage basins. Runoff from the Withilacoochee and Hillsborough basins can-not be evaluated because of diversions through the Withlacoochee-Hillsborough overflow. The Withlacoochee and H~illsborough basins therefore are not included in Table 6 or in the sections on recharge. Numerous other stations -exist on tributary streams and canals within the county. The records of these basins, only a few years of~ which are given here, show great differences in runoff from each drainage basin from year to year, and between basins during the same. year.
The ridges are drainage divides, however, actual surface runoff from them is almost nil due to the thickness and permeability of the surficial -sands, and to the numerous closed basins- of interior drainage located on the ridges. For this reason large areas within a drainage basin actually. contribute very little direct surface run-
FLORIDA GEOLOGICAL SURVEY
off to streams. Rainfall in these areas infiltrates to the water table and percolates through the nonartesian aquifer in response to downward loss, lateral flow, and storage. A part of this water is eventually discharged into surface-water bodies, but only a few such bodies are a part of stream courses.
LAKES
Heath (1961, p. 8) states "Nearly 500 lakes, ranging in size from less than an acre to more than 35,000 acres (55 square miles), lie within the county and along its borders." Nine of the largest lakes are within the broad eastern lowland. They are connected to the drainage systems by means of natural or artificial channels. It is unlikely that these lakes lose water downward through the bottoms because they are within areas of significant artesian flow. Most of the other large lakes in the county are likewise connected to drainage systems. A majority of the lakes in the county, however, are closed basins of interior drainage at the present time.
The entire length of the Lake Wales ridge in this county is pocked with and flanked by innumerable closed basin lakes. There are also many sinkhole basins without lakes, and like most of the lake basins they have no surface outlet. The porosity and permeability of the thick surficial sands of the ridge do not permit surface runoff, and the thickness and permeability of the materials filling the bottom of these sinks likewise do not permit ponding of water. The bottoms of these dry sinks are 20 to 50 feet or more above the water levels in the underlying artesian aquifers, while water levels of the lake-filled basins are generally 2 to 10 feet above these ground-water levels. It seems likely that in much of this area, ground water percolating down the slopes of these dry basins is going into- the artesian limestone aquifers as recharge.
These dry sinks range from 100 to 1,000 feet in diameter at the top of their funnel-shaped basins, but most are 200 to 500 feet in diameter. Topographic depth of the sinks ranges from 9-5 to 75 feet, the smaller and more shallow basins being found on lower parts of the ridge Ranks or within larger and deeper basins.
In the Winter Haven and Lakeland ridges, and in the central and northern inter-ridge areas, dry sinks and basins are few in number, though lake basins of interior drainage are numerous. In these areas the surficial sands are not as thick as in the Lake
-REPORT OF INVESTIGATION No. 44
Wales ridge. In these two areas the surficial sands are underlain by greater thicknesses of less permeable materials, and, being lower topographically, the water table is closer to land surface. The water levels of the artesian systems are also closer to land surface except in the highest parts of these ridges. These factors all operate to increase the percentage of lake-filled basins in these areas.
The lakes of the county are of significant value to the hydrology and economy. They serve to moderate temperatures and climate, they function as reservoirs for water which might otherwise leave the area more rapidly as streamflow, and they provide large supplies of water for irrigation and recreational purposes.
Lakes supply numerous lawn irrigation systems in the cities and towns along the Lake Wales and Winter Haven ridges. In Lakeland and the Lakeland ridge section generally, the use of lakes for lawn and citrus irrigation is relatively much less than in the other areas.
The City of Lakeland pumps water from Lake Parker and Lake Mirror for cooling purposes in adjacent power'plants. Lakes Gibson, Crystal, and Bonny have been used for citrus irrigation in the past, but such usage has been discontinued in recent years largely because of legal proceedings and injunctions. Scott Lake, south of Lakeland., is still used extensively for citrus irrigation whenever irrigation is necessary in the surrounding groves.
Lakes and ponds fluctuate in response to rainfall, groundwater inflow, evaporation, downward loss to underlying aquifers by percolation through the lake bottom, to surface inflow and outflow, and to pumping. The quantities of water involved in these transfers are dependent on topographic, climatic, and geologic factors, and the hydrologic setting of the individual lake basin. The net effect of these factors differs widely from one basin to another, as shown by the hydrographs in figure 12. Relative importance of the controlling factors is not always evident. As a result, the prediction of the effect of individual factors on a given lake is not valid without evaluation of the other factors involved. Detailed discussion of the basins of Lake Parker and Scott Lake in the Lakeland area, and the response of these two lakes to the factors above, are presented in the section of this report entitled Special Problems.
Lakes Wireand Hollingsworth are in the City of Lakeland and on the Lakeland ridge. Lakes Deeson, Crystal, and Bonny are on the lower ground along the east flank of the ridge. Hydrographs
199
B 96 19 4 132 131
'138
I
34 S132
SC?
LAK HOLLINSW"RTH
. . . . . .
______.~. r---.~., -~,,,, ~ ~I,, ~ ,,
. . . . . . . I . . . . .
LAKE DEESON CRYSTAL LAKE
LAKE DEESON
CRYSTAL LAKE CCR Y S T A L L A*
LAKE ES
Figure 12. Hydrographs of water levels in Lakes Wire, Hollingsworth, Deeson, Crystal, and Bonny near Lakeland and rainfall at Lakeland, 1954-59.
74
LAKE WIRE
. I . . .I
i I
1 i
i 1'
1
' ~" '
~,,~~,, ~~
3
--
~ ~ ~ ~ , ~ , ~ ~ ~
REPORT OF INVESTIGATION No. 44
for nearby Lakes Parker and Scott are presented in later sections of this report. Additional data on lake levels, collected as a part of this investigation, may be found in the basic data report (Stewart, 1963). Lakes - Hunter, Beulah, Morton, Mirror and Gibson, all in the ridge section near Lakeland, fluctuate closely in time and amount with Lakes Wire and Hollingsworth.'
Water levels in Lakes Deeson, Crystal, and Bonny, near Lake Parker, declined about 6 feet, and Lake Wire declined 1 foot between December 1954 and July 1956, whereas the water levels in Lakes Parker ' and Hollingsworth and other nearby lakes remained about the same. Hydrographs of the six lakes for 1954 correlate reasonably well.
Lakes Bonny, Crystal, and Deeson have no surface inflow or outflow. Topographic gradients within the basins are generally low, and the slope of. the water table is assumed to be low also. The average flow of ground water into the lakes is probably equivalent to only a-few inches per year over the lake surface, and this amount was undoubtedly below average during the dry period from January 1, 1955 through June 30, 1956. Ground-water outflow in the nonartesian aquifer is believed to be zero.
One phosphate test hole near the west shore of Crystal Lake showed predominantly sandy materials extending from the surface down to the limestone bedrock. A good hydraulic connection such as this may also exist in parts of Lakes Deeson, Crystal, and Bonny, permitting relatively rapid downward leakage.
During the same dry period (January 19 55 to June 1956), pumping from the artesian aquifers increased as recharge decreased, lowering artesian water levels 5 to 10 feet. This increased the hydraulic gradient between the lake levels and the artesian aquifers and probably increased the 'rate of leakage from the lakes.
The combination of decreases in rainfall and* ground-water inflow plus increase in evaporation and vertical leakage appear to have been -sufficient to account. for the decline in lake. levels.
With the return of near- or above-normal rainfall late in 1956, lake levels began to -rise. In November- and December 1956, the outlet of: Lake Parker was raised I foot by the City Engineer of Lakeland. The surplus - water - created was then pumped into Lake Bonny, : The pumped water, -,plus the rainfall., accounts for the sharp rise in the level of Lake Bonny in November 1956, which amounted to approximately 2 feet. Continued above-normal rainfall in most_ of. 19.57 -returned the lakes to, or -above,. -their
FLoRiiDA GEOLOGICAL SUkVEY
1954 levels. Lake Deeson was the only exception to this in the Lakeland area.
The cause of this lack of recovery by Lake Deeson is uncertain and data are few. A major factor may be very localized belownormal rainfall. Similar instances are indicated on the hydrographs of Lake Bonny in September-October 1955, and at other times. This is possible because of the predominantly thunderstorm-type of rainfall in the entire area. Lake Deeson's failure to recover in 1957 and in 1959, as well, may also be due in part to increased local pumpage and downward leakage from the basin.
The lakes all declined in 1958 because of below-normal rainfall. In 1959, record high rainfall was established at the Weather Bureau office at Lakeland when a total of 70.24 inches was recorded. All the lakes, except Parker and Deeson, exceeded their 1954 levels by significant amounts. In September 1959, it was necessary for the city and county to reverse the procedure of 1956, and excess water from Lake Bonny which threatened shoreline property was drained into Lake Parker.
Stage measurements of Lake Ariana in Auburndale, and Lake Hancock near Highland City, in 1958 and 1959 (Stewart, 1963, p. 106) show that these lakes also fluctuate closely with those in the Lakeland area. The range of fluctuations of these lakes ap-, pears to be about equal to those of Lake Wire for the 2-year period.
EVAPOTRANSPIRATION
The term "evapotranspiration" has been used to denote the return of water from the earth to the atmosphere by direct evaporation and by the life processes of plants. It includes evaporation from water surfaces as well as soils and vegetation, and the transpiration by vegetation.
The source of data on evaporation from free-water surfaces nearest the area described in this report is a standard U.S. Weather Bureau evaporation pan at the Orlando Water Plant in Orange County. Evaporation and other climatic factors at Orlando differ somewhat from those at Lakeland, but in the absence of local data, the data from the Orlando station are used in this report. A pan coefficient of 0.7 is applied to correct the annual rate of evaporation from the pan to that from a Iake (Follansbee, 1934, p. 705). The average, corrected, annual evaporation at the Orlando Water Plant, for the period January 1954 through
REPORT'OF INVESTIGATION No. 44
'Oecember 1958, is 40.6 inches. This compares favorably with the (!ata obtained from the now-abandoned Lake Hiawassee station
()f the U.S. Weather Bureau, near Orlando, from 1940-1946. This average also seems appropriate in view of available rainfall and runoff data.
Meyer (1942), on the basis of computed evaporation, produced
seri s of evaporation maps which showed the Polk County area to have an annual average evaporation of 50 inches (op. cit., map no. 4). Meyer's map No. 10 shows this area to have equal mean annual evaporation and precipitation. Since considerable runoff does occur in this area (table 5), the evaporation rate proposed by Meyer is inappropriate.
Transpiration is the release of water from plants during their life processes. No accurate method has been developed for measuring the rate of transpiration of various types of vegetation in a humid subtropical climate such as that of Polk County, but transpiration is undoubtedly a significant factor in the water budget of this area. Studies by Koo (1953) indicate that transpiration of citrus trees is very high. His study utilized test plots of 15-year old Marsh grapefruit trees, and results indicate that average daily consumption of water from the nonartesian aquifer is about 34.2 gpd/tree (gallons per day). The daily consumption varied greatly during the year. Based on this average, and 65 to 70 trees per acre, annual transpiration losses would be about 30 inches per year. If allowances are made for direct reevaporation from the foliage and land surfaceY and transpiration by cover crops and weeds, it is seen that evapotranspiration rates in citrus groves approach open-water evaporation rates in the area. This is also indicated by the work of Penman (1956), who states that transpiration in humid climates near the equator approaches a factor of 0.7 of open-water evaporation. The general close relationship of evaporation and transpiration is also stated by Blaney (1956). For purposes of this report the evapotranspiration rate of 40 inches per year is believed to be reasonable.
GROUND WATER
OCCURRENCE
Ground water is the subsurface water ir. that part of the zone of saturation in which all pore spaces are filled with water under hydrostatic pressure. It is derived-from that fraction of rainfall which has percolated downward, through the soil and zone of
FLoRrDA GEOLOGICAL SURVEY
aeration, and reached the zone of saturation. The ground water then moves laterally, under the influence of gravity, toward places of discharge such as wells, springs, streams, lakes, or the ocear-,. Where hydrologic conditions permit, some of the water may move downward into other underlying aquifers.
An aquifer is a formation, group of formations, or part of a formationY in the zone of saturation, that is permeable enough to transmit usable quantities of water. Ground water may occur under either nonartesian or artesian conditions. Where the upper surface of the zone of saturation, called the water table, is free to rise and fall it is said to be nonartesian. Where the water is confined in a permeable bed between less permeable beds, so that its surface is not free to rise and fall, it is said to be artesian. The term artesian is applied to ground water that is confined under sufficient pressure to rise in wells above the top of the permeable bed that contains it, though not necessarily above the land surface. These less permeable beds are called confining beds.
The height to which water will rise in a tightly cased artesian well is called the artesian pressure head. The imaginary surface coinciding with the water levels of artesian wells is called the piezometrie surface. This surface is generally represented on a map by contour lines that connect points of equal altitude of the pressure surface. Water in an artesian aquifer moves from areas of high artesian pressure toward areas of lower artesian pressure, at right angles to the contour lines representing the piezometric surface. Where the contour lines enclose an area of high water levels (high artesian pressure), the flow is away from the area on all sides. The artesian aquifer is being replenished in such an area. Conversely, where the contour lines enclose an area of low water levels, water is flowing into the area from all sides and is being discharged from the aquifer. Areas in which aquifers are replenished are called recharge areas; areas in which water is lost from aquifers are called discharge areas.
NONARTESIAN AQUIFER
CHARACTERISTICS
In Polk County ground-water supplies are obtained from four different aquifers, which were first recognized by Matson (Matson and Sanford, 1913, p. 389). The uppermost of the four aquifers is in the unconsolidated sand and clayey sand at, and just below, land surface. These sands cover the entire county and,'together with the underlying coarse elastics where present, form the hon-
REPORT OF INVESTIGATION No. 44 79
a-,tesian aquifer. The aquifer is used for domestic supplies and ,or irrigation purposes requiring relatively small amounts of water. Tubular wells in this aquifer range from 1% to 4 inches in diameter and from 7 to 35 feet in depth; there are also a few dug i wells and pits in use. Hand (pitcher) Pumps are commonly used
,for domestic purposes, and gasoline-driven suction pumps are
I
iused for irrigation. The irrigation wells usually do not produce !more than 20 to 30 gpm (gallons per minute), though several are known to produce 100 gpm. or more.
Wells are commonly constructed by driving small-diameter !,pipe into this aquifer. The sand is then cleaned from the pipe, and the well is deepened by water-jetting. There are very few dug, isand-point, screened, or gravel-packed wells in the county. Wells lin the aquifer, as locally constructed, rarely retain their original depth because the loose sand will not stand in the walls of an open hole.
The thickness of the aquifer differs widely over the county, and generally ranges from a few inches to 250 feet. However, extreme thicknesses of 300-600 feet or more are reported along the eastern side and on the crest of the Lake Wales ridge (fig. 4, wells 755-134-1, 801-136-2.9 818-140-1, 820-140-1). Clay content, and hence porosity and permeability, likewise differ widely over the county.
Figures 13 and 14 show the water levels in, and the locations of, some of the nonartesian wells in the county. Though a great number exist, there were not enough to provide the amount of control necessary for a reasonably accurate map of the water table of the entire county.
WATER-LEVEL FLUCTUATIONS
During the course of this investigation, water levels were measured periodically in several wells in the nonartesian aquifer, and continuous recorders were in stalled on others. Hydrographs of representative wells in this aquifer are shown in figure 15. The well illustrated in figure 1-5 is a-part of the permanent network of observation wells maintained in the state, and records of the water levels have been previously published in Water-Supply Papers of the U.S. Geological Survey under the well number Polk 147. Additional water-level data from wells in this aquifer in Polk County have been previously published (Stewart, 1963, table 4).
Water-level fluctuations in this aquifer are due to (1) recharge by rainfall,, and (2) discharge by 'natural gravity flow down gra-
I - I_. .U
II'l 4 r 3
81 52
SI * "
Figure 18. Water-table contour of the Lake Parker area, June 25-30, 1956.
S- -- --------r
*NV fWt., ' . 4
6.
PON"PLANATI % .
Mae .wav .
-"I o - - *
w M. . . 0 4 "'1 -
S --. *- - - -'-I I
tot # . , -APS * I #4 4' gg " ' '. .
oram'
81 55
REPORT OF INVESTIGATION No. 44
26 15' 'ViM
-1 0 45
=' , /-, I \ . r . ,-2.4bE , .N .RDEE . O. TY . II.G . N. s C~OUNTY. . 7.
Figure 14. Map showing water levels in selected wells penetrating the nonartesian aquifer (October 29, 1959 to February 4, 1960). dient to lakes and streams, evapotranspiration, downward loss into underlying aquifers, and pumping from wells. None of the wells illustrated here are affected significantly by pumping. Water-level decline due to downward loss or to natural lateral gravity flow cannot be readily distinguished on the hydrographs. Generally water levels in wells on topographic high areas or slopes will decline at greater rates from these causes than will wells located low on topographic slopes or relatively flat locations. Recharge is reflected by rising water levels, and the rate and amount of rise is determined by the amount of rainfall, the porosity and permeability of the aquifer, and other factors.
The range of fluctuation in nonartesian wells differs widely over the county. The records of six wells, including those shown 'n figures 15 and 30-32, show net changes of 5.5 to 12.7 feet from highest to lowest levels of record in individual wells. The greatest iotal annual fluctuation ranged from 4.3 to 9.6 feet in individual wells.
FLORIiDA GEOLOGICAL SURVEY
105
1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959
Figure 15. Hydrograph showing fluctuations of the water table in a well near Haines City (810-136-2) in the nonartesian aquifer.
UPPERMOST ARTESIAN AQUIFER
The pebble phosphate deposits that immediately underlie the surficial sands of the Lakeland-Auburndale area form an artesian aquifer of undetermined thickness and areal extent which is referred to as the "uppermost artesian aquifer" in this report. The aquifer is in the coarse, sandy, phosphatic gravel zones (matrix) of the phosphate deposits, and is confined above by the heavy dense clays of the Bone Valley Formation, and below by clays which may be either of the Bone Valley or Hawthorn Formations. The few wells penetrating this aquifer are located on the lowland between Lakeland and Auburndale, and are sim ilar in construction to wells in the nonartesian aquifer. Near Saddle Creek the piezometric surface of this aquifer is near the level of the water table (figs. 13 and 14). Generally, however, it is 3 to 6 feet belo-A the water table.
REPORT -OF INVESTIGATION No. 44
In the southern part of the pebble phosphate fields (BartowTiomeland-Ft. Meade, fig. 4) the aquifer may be more productive . !ecause it is generally thicker and coarser. In that area, the piezometric surface may be intimately related to the nonartesian aquifer because. the upper confining bed is more porous than in the Saddle Creek area. Well data from the southern part of the mining area are very few. Though well data are lacking, similar artesian conditions may exist elsewhere in the county in the sands and clays generally overlying the limestone surface. Such, occurrences may be of local nature and unrelated to the geologic units present- in the Saddle Creek-Peace River mining area.
Water-level observations made during the drilling of deep wells in the Lakeland area indicate that the piezometric surface of this aquifer is higher than that of the aquifers below it.
SECONDARY ARTESIAN AQUIFER
CHARACTERISTICS
The secondary artesian aquifer which is formed in the limestone members of the Hawthorn Formation -is used much more than either of the two aquifers previously described. It is confined above by the clays in the upper part of the Hawthorn. Formation or the lower part of the Bone Valley Formation, and is confined below by the blue clay of the Tampa Formation.
The aquifer is present over much of the county south of Polk City. Along much of the northern boundary the limestones are 10 feet or less in thickness, and are soft and deeply weathered. Permeabilities in such locations (wells 805-153-2, 805-156-1, 806-156-1) are very low. Isolated areas in which these limestones have been removed by erosion exist miles south of the general boundary indicated.
An aquifer within the Hawthorn Formation is also reported'in recent investigations of other parts of central Florida. Bermes (1958, p. 19-20) refers to this aquifer as the "Shallow artesian aquifer" in Indian River County; Peek and Anders (1955, p. 20), and Peek (1958, p.'26), report a separate artesian aquifer in these limestone units in Manatee County; Klein (1954, p. 22) likewise reports a separate artesian aquifer in the limestones of the Hawthorn Formation in the Naples area of Collier County. All of these authors find that the pressure head in these aquifers is 5 to 20 feet below that of the underlying Floridan aquifer, in the areas
FLoREDA GEOLOGICAL. SURVEY
concerned.- Peek and Anders (op. cit.) note that the difference in head appears to decrease eastward in Manatee County.
In Polk County many wells draw water from this aquifer in the lowland of Saddle Creek and the Peace River, and these are used for domestic supplies and truck-farm irrigation . Others, used almost exclusively for domestic supplies, are scattered over the southern two-thirds of the county. Locally, a few large diameter citrus irrigation wells produce large quantities of water from this aquifer. Such production is possible because these wells penetrate large solutional caverns in the limestones. Generally wells in this aquifer range from 11/, to 6 inches -in diameter and from 30 to 75 feet in depth. Wells that utilize this aquifer in the southern part of the county and in the ridge sections are considerably deeper because of the dip of the formations and the altitude of land surface. The casing of wells drilled into this aquifer usually terminates in the uppermost part of the limestone, but in some wells it is driven only into the clays of the overlying formations. This latter practice may lead to eventual collapse of the clays and clogging of the wells.
In lowland areas, water levels in wells open only to this aquifer are generally 5 to 10 feet below the water table and are also below water levels in the uppermost artesian aquifer where it is present., In the ridge areas the water level may be more than 100 feet below the water table because of the higher altitude of land surface. Figure 16 shows hydrographs of wells which are open only to the secondary artesian aquifer. Well 744-131-1 is one of the permanent network of observation wells in use by the U.S. Geological Survey, and annual water-level data have been previously published in Water-Supply Papers of the Survey under the well number Polk 51. Additional water-level data has been published by Stewart (1963, table 6). The hydrographs from widely separated wells in this aquifer correlate closely, and the very local effect of pumping causesonly slight variations in the general pattern of the water-level fluctuations.
Locally the secondary artesian and the Floridan aquifers are in direct contact or relatively better hydraulic connection through faulting, jointing, buried sinks, areas of artesian flow, or areas in which the clay of the Tampa Formation is absent. The water level of the secondary artesian aquifer will equal or-closely approach that of the Floridan aquifer in these areas. However., a short distance from such areas the secondary aquifer resumes Its, separate identity.
REPORT. OF INVESTIGATION No. 44
[1 19521195311954119551195611957
Figure 16. Hydrographs showing fluctuations of the piezometric surface in a well near Lakeland (803-153-18) and a well near Frostproof (744-131-1) in the secondary artesian aquifer.
THE PIEZOMETRIC SURFACE
Figure 17 is a map of the piezometric surface of the secondary artesian aquifer in the lowland along Saddle Creek in June 1956. The large cones of depression around the springs at points EA F, and G were caused by discharge from the aquifer in mine pits operating at the time of mapping.- The map was made near the end of -a period of extended drought- (1954 through 1956).
Much of the area between Saddle Creek and the western branch of Saddle Creek, south of the springs at point E, is -a mined-out area, used as a water-storage area in June 1956. Lime-
FLoRIDA GEOLOGICAL~ SURVEY
. -, I~ , KGa S.ofl. J
,.- u-,-
Figure 17. Piezometric-contour map of the secondary artesian aquifer of Lake Parker area (June 1956).
stone of the Hawthorn Formation was exposed at many places in the floors of these pits during mining operations. Artesian springs which issued from the limestone during mining operations have been impounded. Water was pumped from the operating pits and was either used in mining operations or stored in the abandoned pits. Mining in the Saddle Creek mine (south- of point E) ceased January 10, 1957. Mining in the vicinity of the more northerly springs ceased some months later. By February 1960, mining had shifted generally to the north and east of the spring sites shown and was in progress north of 804-151-7. Mining in the Orange Park mine, east and northeast of 807-154-2, began May 5, 1957, and was still in progress in February 1960.
The effect of mining, and the cessation of mining, on a well (803-153-18) in this aquifer is shown by the hydrograph in figure 16. The areal effect of the cessation of mining in the Saddle Creek area, and the generally concurrent return of normal rainfall, is shown by figure 18. Water levels on the ridge areas rose 3. to 5 feet over those of June 1956, while in the lowlands along Saddle
REPORT:OF INVESTIGATION No. 44 87
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Figure 18. Piezometric-contour map of the secondary artesian aquifer in Lake Parker area (October 1959 to February 1960).
Creek water levels rose as much as 15 feet, and 10-foot increases were common.
Well 744-131-1 (fig. 16) located in Frostproof is a nonmining area far beyond the effects of mine pumping. The net effect of generally� comparable rainfall may be seen'by comparing the relative rise of water levels of the wells in the two hydrographs ; 8 feet in well 744-131-1, and 13 feet in 803-153-18.�
In preparing figure 18 a number of revisions of an earlier map (Stewart, 1956, p1. 1) Were necessary because the secondary artesian aquifer did not "actually cover the entire area of the map, as originally thought. These changes are made in figures 17 and 18. Because of intense erosion and possible extensive minor faulting, the limestone of the Tampa Formation is locally the uppermost limestone. The Hawthorn is very thin in a few wells previously thought to be entirely in Hawthorn, and which are now known to be multi-aquifer wells, open to both the secondary and underling Floridan artesian aquifers. "
Figure 19 is a map showing altitudes of water levels in the aquifer during thiewinter months of 1[959-60, Where such data is
88 FLORIDA GEOLOGICAL SURVEY
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available in the county. The map also shows the approximate northern extent of the aquifer. Water levels declined from 0.5 to 3.4 feet in eight observation wells during the period. The map shows that an extensive trough exists in the piezometric surface along the Saddle Creek-Peace River valleys, and that it passes between several significant piezometric highs, which indicate recharge areas. A very extensive piezometric high underlies the west flank of the Lakeland ridge, and occupies much of the southwestern part of the county. Another high underlies a broad flat area south of Lake Buffum. A smaller high area is located on the ridge north of Lake Ariana.
AREAS OF ARTESIAN FLOW
Flowing artesian wells in this aquifer existed as late as 1948 in the general vicinity of well 803-152-2, about a half a mile northeast of the U.S. Highway 92 bridge over Saddle Creek. Water
REPORT OF INVESTIGATION No. 44 89
levels in that area were reported to have been about 2 feet above land surface in 1948, but they had dropped to about 11 feet below the surface by 1656. In 1959 they closely approached land surface for brief periods, and generally were about 2 feet below land surface. The area of artesian flow apparently extended about three-fourths of a mile on either side of Saddle Creek; its northsouth extent is unknown. The area of flow was described by. Sellards and Gunter (1913, p. 263), and Matson and.Sanford. (1913, table facing p. 390) reported a flowing well in this area.
It is likely that flowing wells could be obtained along the valley of the Peace River from the southern county line north midway to Lake Hancock. Observations of ground-water leakage in the secondary aquifer in the vicinity of well 745-147-1 (fig. 19), in August 1958, showed that water levels rise rapidly toward high ground up the valley wall, and the area of artesian flow may be less than 100 feet wide in some places. Progressively lower flow and head may be expected upstream; and in the vicinity of Lake Hancock, wells probably would only flow during brief periods of very high ground-water levels.
WATER-LEVEL FLUCTUATIONS
The range of water-level fluctuations in wells in the aquifer differs widely over the county. The causes of the greatest fluctuations are due to recharge and to pumping from the aquifer. The hydrographs of wells show net changes from highest to lowest water levels of record of 9.4 to 24.5 feet in individual wells. The maximum annual fluctuation in these wells ranged from 7.3 to 17.9 feet.
FLORIDAN AQUIFER
CHARACTERISTICS
The principal aquifer in the area of this investigation is the Floridan aquifer, which consists of . a series of limestones that range from middle Eocene to Miocene in age. It is an artesian aquifer and is the source of all major public, industrial, and irrigation water supplies in the county. The name Floridan aquifer was introduced by Parker (Parker and others, 1956, p. 189) to include "parts or all of the middle Eocene (Avon Park and Lake City limestones), upper' Eocene (Ocala limestone), Oligocene (Suwannee limestone), and Miocene- (Tampa limestone and per-
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PAGE 1
STATE OF FLORIDA STATE BOARD OF CONSERVATION DIVISION OF GEOLOGY FLORIDA GEOLOGICAL SURVEY Robert 0. Vernon, Director REPORT OF INVESTIGATIONS NO. 44 GROUND-WATER RESOURCES OF POLK COUNTY By Herbert G. Stewart, Jr. Prepared by the UNITED STATES GEOLOGICAL SURVEY in cooperation with the DIVISION OF GEOLOGY the BOARD OF COUNTY COMMISSIONERS OF POLK COUNTY and the SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT 1966
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FLORIDA STATE BOARD OF CONSERVATION HAYDON BURNS Govornor 'l'OM ADAMS Sc01,,ta . 111 of State BROWAUD WILLIAMS TrcaBmcr FLOYD 'f. CHRISTIAN Su.p,wintcndcnt of Public bu,t1-itction EARL FAIRCLOTH Attonwu General FRED 0. DICKINSON Conz.ptrolltw DOYLE CONNER Cotmni.8sionc1 of Agriculture W. RANDOLPH HODGES Dfrccto1 iii
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LETTER OF TRANSMITTAL J/o,,iJa {]eo/ogicaf SurvelJ Jaflafuwoo August 16, 1966 Honorable Haydon Burns, Chai1-rna1i Florida State Board of Conservation Tallahassee, Florida Dear Governor Burns : The Division of Geology of the State Board of Conservation is publishing, as Report of Investigations No. 44, a detailed geologic and hydrologic study, covering the "Ground Water Resources of Polk County." This report was prepared by Mr~ Herbert G; Stewart, Jr., geologist with the U. S. Geological Survey, in cooperation with the Board of Conservation, the Board of County Commissioners of Polk County, and the Southwest Florida Water Management Dis trict. The detailing of the geology and hydrology of Polk County pro vi des the necessary data on ma~y of Florida's phosphate deposits, O!l a large part of the Green Swamp water management area, and ,,-m contribute toward the further development of this area. Respectfully submitted, Robe~ 0. Vernon, Di'recto1 Division of Geology
PAGE 5
Completed Manuscript received August 16, 1966 Published for the Florida Geological Survey By Rose Printing Company Tallahassee 1966
PAGE 7
CONTENTS Page /\.bstract 1 Introduction ................... 2 Purpose and scope of investigation 2 Previous investigations .................................................................................... 3 Methods of investigation .................................................................................. 4 Well-numbering system .................................................................................... 6 Acknowledgements 7 Geography 7 Location .............................................................................................................. 7 Topography .................. .. 9 Climate ................................................................................................................ li Transportation .................................................................................................... 12 Agriculture ..... ................................................. ... ...... ............... ........... .......... ....... 13 Mineral resources .............................................................................................. 13 Industry 14 Geology ...................................................................................................................... 14 Stratigraphy 14 Eocene Series 20 Oldsmar Limestone .............................................................................. 20 Lake City Limestone ...................................... . .................. .................. 28 Avon Park Limestone .......................................................................... 30 Ocala Group ............................................................................................ 33 Inglis Formation ............................................................................. 33 Williston Formation ....................... ................................................ 35 Crystal River Formation .............................................................. 35 Oligocene Series 38 Suwannee Limestone 38 Miocene Series 39 Tampa Formation 40 Hawthorn Formation , 45 Undifferentiated ch1,stic deposits ................ .................................... . ......... 46 Phosphate deposits .............................................................................. 4 7 Coarse elastic deposits ................................................................ ~........... 4 7 Structure 48 History of structural movements .......... . ................................................. 51 Solution f ea tu res 52 Cavities .......................................................................................................... 62 Sinkholes ........................................................................................................ 65 Hydrology 69 Surf ace water .................................................................................................... 70 St1•eams .......................................................................................................... 70 Lakes ............................................................ .................................................. 72 Evapotranspiration 76 Ground water .................................... .................. .............................................. 77 Occurrence .................................................................................................... 77 Non artesian aquif e1 .................................................................................... 78 Characteristics ................ ~..................................................................... 78 Water-level fluctuations 79
PAGE 8
CONTENTS Pag<.! Uppermost artesian aquifer 8:! Secondary artesian aquifer 83 Characteristics ............. 8:1 The piezometric surf ace 85 Areas of artesian flow ----88 Water-level fluctuations 89 Floridan aquifer 89 Characteristics ...... . ,. .......... 89 The piezometric surface 91 Areas of artesian flow ..................... 100 Water-level fluctuations ............................................................... : ...... 100 Water-level history ............... 102 Hydra u I ics ........ ..... -.......... 106 Specific capacity of wells ..................... 105 Vertical movement of water .............................. 112 Pumping tests 112 Hydrologic properties of selected limestone core samples .................. 116 Rec barge .. .. . ............. 116 N onartesian aquifer 116 Uppermost artesian aquifer 117 Limestone aquifers ................. 117 Secondary artesian aquifer .......... . ............. 120 Floridan aquifer 121 Qua Ii ty of water ............................................. 129 Chemical constituents ... 129 Change of chemical quality with time 133 Change in chemical quality with depth 133 Water tempera tu re ............ -. 134 Summary of chemical quality ............ . .......... 135 Water use .......................................... 136 Public supply ...... 136 Domestic supply .... 138 Industrial supply 138 Irrigation supply .... . . _ .. ............. 139 ::Miscellaneous sup plies .......... 140 Summary of water use ....... _ .... _ ....... _. 141 Special problems ....................... 141 Lake Parker .. .... .... 14 l History and nature of problem 141 ,v ater budget 147 Con cl us ions ...... .......... -. ......... 151 Scott Lake . .................. 158 History and nature of the problem 153 Water budget 158 Cone 1 us ions ................ 161 Summary .... ..... ... ........ _ 161 References . . . . . .. . . .. 165
PAGE 9
ILLUSTRATIONS Figure Page 1 Map of Florida showing the location of Polk County and the wellnumbering system ...... ................................. . .............................................. 6 2 Topographic map showing major physiographic features ............ .. .. 8 3 Graph showing total annual rainfall at Lakeland, 1915-69 11 4 Map showing the location of selected wells ............. Facing page 14 6 Geologic map of the pre-Miocene formations 34 6 Geologic sections along lines A-A' and B-B'. Sections located on Figure 6 43 7 Geologic sections along lines C-C' and D-D'. Sections located on Figure 6 ......•... .............................................................................................. 44 8 Structure-contour map on top of the Inglis Formation .................... 50 9 Map showing the location .of wells penetrating solution features in the limestones ................................................................................... . .......... 63 10 Map showing location of recent sinkhole collapses 66 11 Photographs of 1ecent sinkhole collapses ...................... . . ~.............. 68 12 Hydrographs of water levels in Lakes Wire, Hollingsworth, Deeson, Crystal, and Bonny near Lakeland and rainfall at Lakeland, 1954-59 .. 7 4 13 Water-table contour of the Lake Parker area, June 25-30, 1956 ...... 80 14 Map showing water levels in selected wells penetrating the nonartesian aquifer, (October 29, 1969 to February 4, 1960) ................ 81 15 Hydrograph showing fluctuations of the water table in a well near Haines City (810-136-2) in the nonartesian aquifer 82 16 Hydrographs showing fluctuations of the piezometric surf ace in a well near Lakeland (803-153-18) and a well near Frostproof (744131-1) in the secondary artesian aquifer .......................................... .... 85 17 Piezometric-contour map of the secondary artesian aquifer of Lake Parker area ( June 1966) .......................................................................... 86 18 Piezometric-contour map of the secondary artesian aquifer in Lake Parker area (October 1959 to February 1960) .................................... 87 19 Piezometric-contour map of the secondary artesian aquifer ( October 1959 to Februa1y 1960) ........................................................ ~......... 88 20 Piezometric-contour map of the Floridan aquifer ( October 1959 to February 1960) ................................................................... Facing page 90 21 Piezometric-contour map of the Floridan aquifer in northwest Polk County (June 1966) 98 22 Piezometric-contour map of the Floridan aquifer in Lake Parker area ( October 1969 to Feb1•uary 1960) 99 23 Hydrographs of fluctuations of piezometric surface in a well near Lakeland (769-168-1) and a well near Davenport (810-136-1) in the Floridan aquifer 101 24 Map of peninsular Flol'ida showing the piezometric surf ace of the Floridan aquifer in 1944 123 25 Piezometric-contour map of the Floridan aquifer at Lakeland (Novem her 20, 1959 ) ......................................................................................... 12 8 26 Map showing hardness of water in selected wells in the Floridan aquifer ......................................................................... ..................... ............. 132 ix
PAGE 10
27 Map showing water temperatures in selected wells in the Floridan aquifer 184 28 Graph showing total annual municipal pumpage by City of Lakeland, 1928-69 ...... ................. .. .............. ........ .......................... lH 7 29 Log of sediments penetrated in test hole 805-156-A, in Lake Parker .. 144 30 Hydographs of water levels in Lake Parker and in wells 803154-10 and 806-154-1, 1954-66 .................................................................. 146 31 Hydrographs of water levels in Lake Parker and in wells 805-165-1, 2, and 3, 1956-59 .................................................................................... 146 32 Hydrographs of water levels in Lake Parker and in wells 806155-1, 2, and 3, during 1958 ................................................................ 147 33 Hydrographs of water levels in Scott Lake and in wells 768-166-6, 757-155-3, and 757-166-6, 1954-60 ....... ..................................................... 154 34 Hydrographs of water levels in wells in the nonartesian aquifer in the Scott Lake area ................. ................................................ 155 35 Map showing water levels and other features of the Scott Lake area, July 1956 ........................................................................................ 166 36 olap showing water levels and other features of the Scott Lake area, October 1959-February 1960 .......................................................... 157 TABLES Table 1 Mean monthly temperature and rainfall at Lakeland, Florida for period 1915 to 1969 12 2 Total annual rainfall at U.S. Weather Bureau stations in Polk County, 1954-59 12 3 Geolo~ic data from wells in Polk County .. 16 4 Solutional features penetrated l>y wells in Polk County .................... 64 5 Records of the occurrence of recent sinkholes in Polk County .......... 67 6 Annual runoff by drainage basins, 1954-59 71 7 Water levels observed during drilling operations .............................. 92 8 Net change in water levels in wells in the Floridan aquifer, 1934-59 103 9 Specific capacities of selected wells in Polk County ........................ 104 10 Specific capacities of wells in Polk County .............. ........................... 106 11 Hydrologic properties of limestone core samples from well 805154-8 ........... ..................... _ -............. .... 113 12 Range of concentration of chemical constituents in waters of Polk County 180 13 Annual metered pumpage by municipal systems in Polk County, 1954-59 1~6 14 Stream-flow measurements in the vicinity of Lake Parker and Saddle Creek ...................................................................................................... lA 8 X
PAGE 11
GROUND-WATER RESOURCES OF POLK COUNTY, FLORIDA By Herbert G. Stewart, Jr. ABSTRACT Polk County, Florida is located approximately in the center of the Florida peninsula, and is an area which requires large quanti ties of water for industry, agriculture, and municipalities. Nearly all water supplies in the county are obtained from ground-water sources. Domestic and small irrigation supplies are obtained from limestones of the Hawthorn Formation of Miocene age, and to a lesser degree from unconsolidated elastic deposits which range in age from middle Miocene to Recent. Large water supplies are ob tained from the Floridan aquifer which includes limestones ranging in age from middle Eocene to middle Miocene. Geologic studies near Lakeland show that the Avon Park Limestone is the lowest unit of the Floridan aquifer, and that there has been no circulation of ground water in the underlying formations. The southern end of the Ocala uplift extends into Polk County and the highest piezometric levels in the Floridan aquifer occur in the county. As a result of the Ocala uplift the rocks of the _ 11'loridan aquifer have been highly fractured which has resulted in solutional development of the limestone and extensive cavern : systems. The fracturing has also permitted the free circulation of water between all units of the aquifer. \'7 ater recharges the Floridan aquifer principally by down ward percolation from surficial sands and through the intervening units to the Floridan aquifer. Only a few inches of rainfall per year enters the aquifer as recharge in the county. Water budget analyses for two lakes near Lakeland, during the first 6 months llf 1956, show that the lakes recharged the underlying limestone aquifers. Lake Parker recharged water to the Floridan aquifer at . rate of about 2.5 inches per month and Scott Lake recharged Nater to the limestones of the Hawthorn Formation at a rate of -tbout 5 inches per month. Data suggest that other lakes in the '.Ounty may also recharge the aquifers at slow rates. During 1959, approximately 80 billion gallons of ground water -.vere pumped from the aquifers in the county. During the same :1ear approximately 120 billion gallons were determined to rel
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2 FLORIDA GEOLOGICAL SURVEY charge the limestone aquifers within the county. The excess o:.: about 40 billion gallons moves through the aquifers into adjacen::: counties. The potential availability of ground water in the county can be increased by using more ground water which in turu creates increased storage in the aquifers. INTRODUCTION PURPOSE AND SCOPE OF INVESTIGATION The investigation upon which this report is based was begun in April 1954 by the U.S. Geological Survey in cooperation with the Florida Geological Survey and the Board of County Commis sioners of Polk County. Preparation of the final phases of the manuscript was effected with the cooperation of the Southwest Florida \Yater Management District. The general purpose of the investigation was to provide basic information to assist in the in telligent developn1ent of the water resources of Polk County. The investigation was specifically designed to (1) determine the re lationships between some of the lakes in the county and the ground-water aquifers, including the effects of large withdrawals of ground water on lake levels; (2) determine the mechanics and quantities of recharge to the principal ground-water aquifers and to locate areas in which such recharge is occurring; and (3) de termine amounts of water being used and to estimate the total amount available from the principal aquifers. This report presents general information on the geology and hydrology of the county and specific information on two lake basins located in the northwestern part of the county. The rela tionship of the many lakes in this area to the ground-water supply and the effects of large withdrawals of ground water on both ground-water and surface-water levels are matters of great in terest in the county. The complexity of the hydrology of the area made it necessary to study the geology in considerable detail. A preliminary report of the investigation was prepared by the author (1959) and presented detailed information on specific problems relative to two lakes near Lakeland. This report constitutes the final interpretative report of th investigation. A companion report of basic data was also prepared (Stewart, 1963) and contains well data, chemical analyses, water
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REPORT OF INVESTIGATION No. 44 3 bvel measurements and lake-stage n1easurements, and other data !~athered during the course of the investigation. PREVIOUS INVESTIGATIONS Some geologic and hydrologic work has been done in Polk County as part of regional or statewide investigations. Most of this work has been done by the U.S. Geological Survey a:hd the Florida Geological Survey. Cooke (1945), Vernon (1951), and Parker, Ferguson, Love, and others (1955) described the general geology of central Florida and made many references to Polk County. Cole (1941, 1945), Mansfield (1942), Cathcart and Davidson (1952), Davidson (1952a, 1952b), Cathcart and others (1953), Carr and Alverson (1953, 1959), Puri (1953b, 1957), Bergendahl (1956), Cathcart and McGreevy (1959), Ketner and McGreevy (1959), Altschuler, Clark, and Young (1958), and Altschuler and Young (1960) dis cussed the geology of one or more of the formations which are present in the county. Fenneman (1938), Cooke (1939), MacNeil (1950), and White (1958) discussed the topographic features of central Florida, and their origin and development. Sellards (1908), Sellards and Gunter (1913, p. 262-264), Mat son and Sanford (1913, p. 388-390), and Gunter and Ponton (1931) prepared early discussions and data concerning ground water in Polk and other counties of central Florida. Stringfield (1935, 1936, p. 148, 172-173, 186) investigated ground water in the Florida peninsula and presented data from Polk County. An important result of his investigation was a piezometric map of the principal artesian aquifer of peninsular Florida (the Floridan aquifer in this report) which shows areas of recharge to and dis eharge from the aquifer in Polk County. The map was expanded to include most of northwestern Florida and part of southern c:eorgia by the work of M. A. Warren, V. T. Stringfield, and 1 1 '. Westendick 1 , and was shown by Cooper (1944, fig. 2), Warren (1944, fig. 3), and Unklesbay (1944, fig. 5). Cooper (1944), ftringfield and Cooper (1951a), and Cooper, Kenner, and Brown (1953) discussed the ground water of Florida and referred to re t1arge of the principai artesian aquifer in Polk County. Papers by J 'erguson, Lingham, Lov_e, and Vernon (1947), and Stringfield , nd Cooper (1951b) described the geologic and hydrologic fea1 Oral communication, H. H. Cooper, Jr., U.S. Geological Survey, May 4, :-961.
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4 FLORIDA GEOLOGICAL SURVEY tures of springs in Florida and presented flow measurements and other data for some springs. Peek (1951) discussed the cessation of flow of Kissengen Spring in Polk County. Collins and Howard (1928), Black and Brown (1951), and \Vander and Reitz (1961) discussed the chemical quality of ground and surface water in Polk County and other parts of Florida, and presented many analyses. METHODS OF INVESTIGATION Field work began May 1, 1954 with an inventory of water supplies in the northwestern part of the county. Later the inven tory was extended to include the remainder of the county. Infor mation on the depth, depth and diameter of casing, water level, yield, type of pump, use, and quality of the water was obtained for more than 1,300 wells. During the inventory, specific wells were selected for the ob servation of water-level fluctuations. Water levels were measured periodically in most of the observation wells, however, continuous water-level recording instruments were installed on 13 of them. The levels of several lakes in the northwestern part of the county also were measured periodically and recording gages were in stalled on Lake Parker and Scott Lake, in the Lakeland area. Current-meter and temperature logs were obtained from 12 wells in the county. Samples of water were collected from wells and surface sources for chemical analysis. Composite water samples were collected from wells being pumped. Water samples were also collected from hailers, both during drilling operations and after completion of wells. Consolidated rocks were found exposed at land surface in small areas of extreme northwestern Polk and adjacent counties. These out-crops were examined, mapped, and samples collected in reconA naissance with Mr. E.W. Bishop, Florida Geological Survey. DurA ing mining operations the phosphatic limestones of the Hawthorn Formation were briefly exposed in the bottoms of some of thd mine pits in the Lakeland area, and these were studied and de scribed whenever possible. Unconsolidated deposits, below tho loose surficial sands, were found exposed in road-cuts, borrow-pib in the ridge areas along the newer highways, and in phosphatf~ mine pits and these deposits were briefly studied and described. Studies of rock cuttings were made during well-drilling opera•
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REPORT OF INVESTIGATION NO. 44 5 ti ms. Samples from about 250 wells in Polk County are presently fi i ad at the Florida Geological Survey, most of which were col leded and donated by the local well drillers. Cuttings from 25 dt!ep wells, 14 shallow wells, and 4 test holes were collected and examined during the investigation. Eleven other sets of samples from wells in the county were collected and logged by other geol ogists of the State and Federal Surveys. Most of these wells were drilled by the cable-tool method. A few wells were started and the casing installed by the rotary method, and the open-hole portions of the wells completed and samples collected by the cable-tool method. Two deep exploratory wells drilled near Lakeland by private industry during 1959-60 made an important contribution to geologic and hydrologic knowledge in this county. The first well, 805-154-8, five miles northeast of Lakeland, was continuously cored from 58 feet below land surface to a total depth of 1,479 feet with more than 95 percent core recovery. The second, 801-2003, three miles southwest of Lakeland, was cored from near the top of the thick dolomite interval of the Avon Park Limestone ( 652 feet below land surface) to a total depth of 1,846 feet. The forma tions penetrated by the wells include formations deeper than those normally penetrated by water wells in the county. ! The cores from these two wells provide the most complete and ! accurate record obtainable from Polk County of the rock f orma1 tions penetrated and together with the electric and gamma-ray 1 logs from the two wells, are used as basic control for all geologic studies in this report. Rock cuttings and ele~tric logs from other wells studied during this investigation are used as second-order control ; other sets of well samples and electric logs in the files of the Florida Geological Survey are used as third-order control; electric logs of wells from which no samples are available are . used as fourth-order control. Additional geologic information was obtained from 65 electric lot~s of wells made with a single-electrode logger and from 61 g: 1 mma-ray logs. For geologic correlation 29 electric logs and 30 grmma-ray logs were made in wells from which rock cuttings w : re available for study. The electric logs served as the basis for m 1ch of the interpretation of geologic structure in this report. The g i mma-ray logs were less useful as a geologic tool, but served as an m xillary source of data with reference to pebble-phosphate de P 3its and the Miocene limestones. -Drillers and well owners have a: : o given to the State or Federal Geological Surveys 146 descrip
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6 FLORIDA GEOLOGICAL SURVEY tive logs of wells from which cuttings were not collected. TheHe descriptive logs have been of value in the interpretation of ground water conditions, general lithology, and geologic structure. WELL-NUMBERING SYSTEM The well-numbering system used in this report is based on latitude and longitude coordinates. Figure 1 shows the well~ numbering system used in this investigation. The well number was assigned by first locating each well on a map that is divided into I-minute quadrangles of latitude and longitude, then numbering each well in a quadrangle in the order of inventory. The well num ber is a composite of three numbers separated by hyphens: The first number is composed of the last digit of the degree and the CtQ' .. , of tori9,f\ld1 •fl' of tf'lt Gttenw,tf\, t1191011e1 , p , .,,.. "'• t an _,N W .. . .. •r' ----------1;, ~ --+ . ... . .. ?' f ..., . : -.-_ . i I . •,.. : ....; .,,. . .... _ \. . . ___ G __ E O R G I .... -.r -l ... . ...... .,... r!' .-';-1 ....... , .... ;,...;..,.-........... '"'-..,_JI'" . , . ,,,LIO• 1~,,._ ) ••Ort,. ,h_ ----~ ... I ' , 8,-00 ' ==== ==mimtmmmt 1m . 1 :::1~:n:,."ill "~!,--+-t-::-::-::-m :,0 ffi!mj!ffiffit =t~=t~== . I E5~~~~~~H; !lli :!:5;E!;F.5E:Effi:!3 ~ :! ! ::,: : ,, -oo : ii ~~ ;; ; ... !t : ua , . :I r,i.,"'D•, 81! rs; I Ir•'' 8.Z~ l l ! . , a '"'• tn,,d w,11 ~...-n,,,_..ied ,f'\ '"'• ,_ "''"'"''• q wOdrcJ"Qle r.or lh a, H'le .! :,--;" ' >,l t QIII I u r ,o Mudl end MIi r,f t~ .. , .J I' ~id.on ;>f 'tl "IJ•luOI :ii,...-.;it, 0,,. ""l'T\beted ,ti "" IOm4t •'" J ! o,t,iac,ef'IC! c,f ffi9 0,_ ,n •htt" '"-'..,. ,1'Vet'lu-.d --, .. . + -' ' , ,. ... E t 0 Figure 1. l\Iap of Florida showing the location of Polk County and the well-numbering system.
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REPORT OF INVESTIGATION No. 44 7 b o digits of the minute of the line of latitude on the south side of a 1-minute quadrangle ; the second number is composed of the last digit of the degree and the two digits of the minute of the line of longitude on the east side of a 1-minute quadrangle; and the third number gives the order in which the well was inventoried in the quadrangle. For example, well 826-131-3 is the third well in ventoried in the 1-minute quadrangle north of 28' north lati tude and west of 81 ' west longitude. By means of this system, wells referred to by number in the text can be located on the vari ous plates and illustrations of this report. The same system is used in numbering test holes, exposed sec tions, sampling stations, and points of various observations that were collected or described, except that consecutive letters of the alphabet are used instead of consecutive numbers. For example, 805-1'56-A was a test hole. The test holes were filled and aban doned immediately after drilling, and therefore are distinguished from wells. ACKNOWLEDGMENTS The investigation was greatly facilitated by the interest, co operation, and assistance of city, county, and industrial officials~ residents, and landowners. Well drillers in the area have repeat edly made their time, experience, and records available to the author. Appreciation is here expressed to all of these people. Grateful acknowledgment is here made toE. W. Bishop, geolo gist, Florida Geological Survey, and F. W. Meyer, geophysicist, U.S. Geological Survey, for the many beneficial discussions and the exchange of ideas and concepts during the investigation. GEOGRAPHY LOCATION Polk County comprises an area of about 1,860 square miles in tl e central part of peninsular Florida. ( See figure 2.) The county ,, 1s established February 8, 1861, by separation from what was tI en Hillsborough County. Hetherington (1928, p. 14) records an a count of Mr. B. F. Blount that indicates that the population in C ~tober 1851, of what is now Polk County, totaled about 20 fami
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8 FLORIDA GEOLOGICAL SURVEY r "I , ., ;...._....a. --__ _ _ _ , ,o -: , c t"' c i tv\ " 4' ~:, ,. 1; 1! .,. .. , . . , , , ... . , .,,, ! ( , ... . , : ~ ....... I ''t0" Ht , , .. . Figure 2. Topographic map showing major physiographic features. lies, a garrison of soldiers, and some Seminole Indians. Since that time the population has increased steadily. The following population figures for the county were taken from published reports of the U.S. Bureau of Census: 1890 7,905 1900 12,472 1910 24,148 1920 38,661 1930 72,291 1940 86,665 1950 123,997 1960 195,139 The population is concentrated in the cities and towns along the ridges in the interior of the county. Several hundred square mils in the northern part of the county and much of the area east cf the Lake '\Vales ridge is sparsely populated. The southern part cf the county is also sparsely populated. Generally, these areas are
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REPORT OF INVESTIGATION No. 44 9 pcior1y-drained grasslands and flatwoods, relatively low and flat, and are largely devoted to cattle ranching. During the period of this investigation many isolated, well-drained hills and low ridges within the northern and southern areas were cleared and citrus trees were planted. The three major ridges and much of the well-drained inter ridge areas are devoted to citrus groves. Numerous small truck farms are also found in the inter-ridge areas. Vast areas in the southwestern part of the county have been mined for pebble phosphate. Much of the mined-out area has not been improved and now stands as rugged spoil piles. TOPOGRAPHY Polk County is part of the Central Highlands physiographic division of Cooke ( 1939, p. 14, fig. 3), the Limesink and Lake Re gions of the Floridan Section of the Atlantic Coastal Plain prov ince of Fenneman ( 1938, p. 46-65, and the Atlantic Coastal Plain ground-water province of Meinzer (1923a, p. 309-314). The county is part of the highland area that trends along the longitudinal axis of the Florida peninsula. The major topographic features of the county are three long, irregular, north-south trend ing ridges which are separated and bounded by relatively flat low land. These and other topographic features are shown in figure 2. ! The easternmost of the ridges extends from the common corner of Polk, Osceola, Orange, and Lake Counties approximately south through Haines City, Lake Wales, and Frostproof, and into the southern part of Highlands County. MacNeil (1950, p. 101) has referred to the eastern ridge as the Lake Wales ridge, and White (1958, p. 10) also uses this name. This is the highest, longest, and narrowest of the three ridges in the county. Altitudes on the crest of the ridge range from 150 to 305 feet above msl (mean sea level) and are highest at Lake Wales and Babson Park. The central, or Winter Haven ridge (White, op. cit.), begins abruptly at Polk City, and continues south-southeastward through Auburndale and along the east side of the Peace River valley to F ~ . Meade. It appears to merge with the Lake Wales ridge about 4 miles southwest of Frostproof. This ridge is actually a zone of snail ridge-remnants approximately 8 miles wide. Between Bar tl w and Ft. Meade this ridge becomes a much more massive unit, b : oader and higher than the northern unit. Altitudes along the C J est of the northern unit range from 150 to 200 feet msl, and
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10 FLORIDA GEOLOGICAL SURVEY much of the southern unit ranges from 200 to 280 feet msl. The westernmost ridge, or the Lakeland ridge (White, 19!i8, op. cit.), begins abruptly about 10 miles northwest of Lakeland and extends south-southeastward through Lakeland and between Bartow and Mulberry, to the vicinity of Ft. Meade. Altitudes along the crest of the ridge range from 150 to 270 feet msl, and much of it lies above 200 feet msl. The Lakeland ridge is more continu ous and narrow than the Winter Haven ridge. The Lakeland nnd \Vinter Haven ridges appear to trend slightly more north-west. southeast than the Lake Wales ridge. All of the ridges are being lowered and dissected by sinkholes. The Lake '\Vales ridge has been transected by sinks in the Frost proof area, and many other saddles in the ridge are approaching complete transection. The northern pnrt of the Winter Haven ridge has been thor oughly dissected by sinks. However, the massive southern unit re tain~ a relatively juvenile linenrity on the western flank, and iR being slowly dissected on the lower parts of the eastern flank. Transection of the two units of this ridge has been complete in a broad area along Florida Highway 60, north of Alturas. The Lake land ridge is being dissected much more slowly than the other two, though large non-Jake sinks appear to be more numerous in this ' ridge than in the others. The northern part of the county, west of the Lake Wales ridge and north of the other two ridges, is n broad poorly-drt\ined flat land that slopes northwestward from about 140 feet msl to about 90 feet msl. It is an area of pine flatwoods, cypress swamps ( called domes), and intervening grasslands. On the eastern flank of the Lake Wales ridge there are two large areas of dune-covered terraces and _sand hills, one located southeast of the city of Lake Wales and another north of Daven port. East of these is the broad, slightly rolling to flat, marshy lowland of the Kissimmee River. Another broad, flat to rolling, lowland exists across the south ern part of the county, west of the Lake Wales ridge and south of the other ridges. Much of this area is poorly-drained pine flat ,voods. The interridge areas are partly rolling lower land, a ,1d partly low flatwoods and marshes. l\Iaximum local topographic relief in the county is 219 feet in the Lake Lenore basin, southeast of Babson Park. Total relief in the county is 255 feet (from 50 to 805 feet msl). Surface drainage is poorly developed in the county. On the fl:1t
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REPORT OF INVESTIGATION No. 44 11 lunds there are hundreds of perenninl and ephemeral swamps and b: , sins of interior drainage. In the ridge areas, basins of interior drainage are even greater in number, depth, and diameter than on the lower flatlands. In both types of topography some of the basins of interior drainage (sinkholes) contain lakes. CLIMATE All climatic data used in this report are taken from the pub lished records of the U.S. Weather Bureau. The data from the Lakeland station are believed to be generally representative of the county. 1,he area has n humid subtropical clima.te and only two pro nounced seasons-winter and summer. The average annual tem perature is 72F, and the average monthly temperatures range from 62F in December and January to 82F in August. The av erage annual rainfall is 51.43 inches, about three-fifths of which occurs from June through September. Most of the rainfaU con1es from thunderstorms, which average about a hundred per year. Total annual rainfall at Lakeland, for the period of record, is shown graphically in figure 8. The mean monthly temperature and rainfall through 1959 ar-~ ehown in table 1. 'l,otal annual rainfall at the Weather Burenu stations in the county during the period of this investigation is given in table 2. on,,---------------------------, 701---------------------------f'.,.. Figure 3. Graph showing total annual rainfall at Lakeland, 1916-59.
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12 FLORIDA GEOLOGICAL SURVEY It is to be noted that the rainfall at Lakeland, Bartow, and Lake Alfred Experiment Stations in 1959 established record highs for these stations. The Mountain Lake station lacked 3 inches that year of equaling its record high. The second lowest rainfall of rec ord for Lakeland (36.30 inches) occurred in 1954, and the lowest rainfall of record at Lake Alfred in 1955. Table 2 clearly indicates the great difference in local precipitation in this area. The differ ence between highest and lowest total annual rainfall for the sta tions shown exceeded 20 inches in 1957 and 1958. TABLE 1. Mean monthly temperature and rainfall at Lakeland, Florida1, for period 1915 to 1959. 'I cmpcraturo Rainfall Month (OF) (inches) .11\nuary 02.4 2.21 February 63.0 2.47 March 67.3 3.00 April 72.0 3.24 May 77.0 4.43 Juno, 80.4 7.38 July 81.6 8.02 Aua;ust 82.0 7.30 &-ptcmbcr 80.!J 6.42 October 74.7 2.88 November 67.2 l.72 I>,•cember 63.0 1.07 .\nnu:u 72.7 61.78 1 l\8. Wrl'thcr Burcl'u, Local Climntologicul Du.ta with compnmtivo tlntu., l.1ikclanil, Horidu. for period 1015 to 1050. TABLE 2. Total annual rainfall at U.S. Weather Bureau stations in Polk County, 1964-69. Menn ~tation 105-1 10.>5 1056 1057 1058 1050 nnnuul• Bu.rtuw 51.10 41.41 46.3 . 73.72 61.82 83.44 Lalte Alfred E:tper. Stn. 38.27 35.66 44.40 57.0U 40.80 070.67 Lakl!Wld 36.30 44.08 45.12 62.38 41.74 70.24 Motustain !Ake (n.t l..aku WIiles) 46.05 43.08 .35 58.21 65.00 71.42 Winter Ha.v,,n 38.68 38.78 44..55 66.07 52.73 73.28 Bu.bean ~l,c 30.54 61.14 57.50 06.07 1 l~.S. W e11ther Bun:u.u 1 "Climatological D11ta-l•'loridn-Annulll Summnry" 1054 through 1959 , Not computeJ-le:i:s tnan 20 yeara record availu.blo a From U .:,. W ellther Bureau Iona-term recorda l' t'lltima.ted TRANSPORTATION .12 51. 61.-13 62.70 1 I The principal highways in the county are U.S. Highways 9J, 27, and 17, which are north-south routes, and U.S. Highway !i2 and Florida Highway 60, which are east-west routes. These a1 e
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REPORTOF INVESTIGATION No. 44 13 augmented by a network of additional state and county roads. However, in the less populated northern and eastern parts of the county there are only a few graded roads. Most of the towns and cities of the county are served by main lines of the Seaboard Air Line or Atlantic Coast Line Railroads. In general, the area is poorly served by direct air service; only Lnkeland has regularly scheduled flights. AGRICULTURE Various types of agriculture play an important part in the economy of the area, and many are important water users. The most important type of agriculture is the growing of citrus fruits, principally oranges and grapefruit. Cattle ranching is also an im portant part of agriculture. Truck-farming, lumber, and other ag ricultural pursuits are of less importance in the economy of the county. In the 1954 Agricultural Census (U.S. Bur. Census, 1957, p. 149), Polk County ranked first in the State in the production of citrus fruits, having 8,012,894 orange, grapefruit, and lemon trees. The county is also a leader in the production of the less common citrus fruits, such as limes, tangeloes, and kumquats. Normally, the citrus groves are irrigated one or more times a year as required. Locally the growing and marketing of truck-farm crops such as strawberries, peppers, beans, squash, and other vegetables is important. The truck farms are relatively small, and normally sev eral different crops are grown in rotation during a single year. These crops are generally irrigated heavily and often. In 1954 Polk County ranked first in the State in the_ produc tion of cattle (U.S. Bur. Census, 1957, p. 107) with a total of 121,773 head. Ranches are usually large, and are located on the flatlands in the peripheral areas of the county. MINERAL RESOURCES At present eight companies are actively engaged in open-pit mining of pebble-phosphate in the county. Production in 1959 to ta:ed 10.2 million long tons of phosphtae rock 2 The mining process uflizes large quantities of water; however, extensive storage, set tlhg, and recirculation practices reduce the amount withdrawn 2 Personal communication, Mr. E. W. Bishop, Florida Geological Survey, N, vember 7, 1960.
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14 FLORIDA GEOLOGICAL SURVEY from ground-water aquifers. More than ten companies were mining (dredging) silica sand from the unconsolidated deposits in the county in 1960. Five of these companies are located in the Lake Wales ridge, where the thickest deposits are found. Other companies were operating in or near Mulberry, Bartow, Ft. Meade, Waverly, and Winter Haven. Sand and gravel production totaled 8.8 million short tons in 1959 ( U.S. Bur. Mines, 1959, table -5). Most of the water used in this production is readily obtained from the excavations, and does not represent significant industrial consumption of ground-water sup plies. Limestone has not been mined in the county due to the thick ness of the unconsolidated overburden, low purity of the upper most limestone in some areas, and high ground-water levels. How ever, n relatively large, previously unmapped area of silicified limestone, cropping out in the northwestern part of Polk County and southern parts of adjacent counties, which may become im portant to the economy of the county, is discussed later in this report. Silica replacement of the limestone surface and artesian ground-water conditions present problems in the newly mapped area, but an economic potential is clearly present. In 1960, agricul tural limestone was being obtained from the Ocala-Brooksville area to the north or from western Manatee County to the southwest. INDUSTRY One of the major inqustries in the county is the packing, can ning. and concentrating of citrus fruits and juices. Another, an
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REPORT OF INVESTIGATION No. 44 15 \ Jmposition of the rocks afl:ect the chemical composition of the ,:ater contained and the rate of ground-water n1ovement through i nem. The thickness, areal extent, and fracturing of the various rocks will also influence the rate of ground-water n1oven1ent and yield of wells. Structural deformation and chen1ical alteration also nffect the rate of n1ovement through individual rock units and be tween units. Vernon (1951), Cooke (1945), and n1any others have described the rock units present in Polk County, their general relationships and geologic history, the origin of the different unit nan1es, and the criteria for their identification. However, there has been no previous work which describes the geology of the county in suffi cient detail to understand the hydrology of the rock units. The areal extent of the various units has not been previously established. The literature notes cavernous limestone in central Florida but does not detail the occurrence nor adequately consider the origin of these solution features which are so important to ground-water movement. The work of Vernon (1951, pl. 2) sug gests the presence of extensive fracturing in the rocks of Polk County which would also greatly influence the hydrology. The existing literature does not define the thickness or depth of rocks which contain fresh water. Thus, a considerable part of this in vestigation was devoted to geologic studies that were aimed at providing more detailed information on hydrology. All of the consolidated rocks of the county that are normally penetrated by water wells are limestones or dolomitized limestones. Over n1ost of the county these are buried by phosphatic clays which are in turn covered by a blanket of sand that constitutes the surficial material. Consolidated rocks crop out in a few, rela tively small, areas in the northern part of the county. Most of the geologic information for this report was obtained from rock cut tings taken from wells and by the interpretation of electric and gamma-ray logs of wells. Figure 4 shows the location of we11s in Polk County. Table 3 shows the depths to the tops of the various geologic iormations as determined during this investigation. Table 3 does ot include a summary of open-file geologic logs of wells by the ','Jorida aeological Survey and which were used in the present -tudy. In the following paragraphs the rock formations penetrated >y wells in this county are discussed from oldest to youngest. The stratigraphic nomenclature used in this report conforms 0 the usage of the Florida Geological Survey. It conforms also to
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TABLE 8, Geologic data from wells In Polk County .... Approximate depth to top of each formation given fn feet Data source: D, drUler'a Jog: G, gamma-ray log: 0, below land aurface: a, absent: c, cased oft'; e, estimated, S, samples: X, electric log, APPROXllUTE DEPTH TO TOP OF FORMATION FOS Jr"wtlwro 0C"Ala OrouJi usos well Altitude Formation A,,aq well number of l&Qd (llmeatone T1m1~ Su"'&DDee cg:,tat Park DUblber CW•) aurface only) Fumu.tion Liuaeltone n ,er Willilt..aq lll,llil Llr1U1111too.e Did.a IIIOUr'OCI Remark, '149-160-2 .... 98 0 0 882 .(.{0 580 621 703 o,x 7''4,-181-1 ... us 202 282 336 ... 583 620 X P-51 7'4'-167-l 8852 248 c219 c300 448 710 D,X 7'45-lat-1 6351 e185 140 a? 230 280 ... 8 Tampa clay DOt :Bi.,_11t.ed r ID a&mP1e1: no r'• las avallanle. '143-163-1 2304 J68 ISO 230 c21r; 380 5001 000 030 D, S 7'-U-168-8 .... 187 0 0 c394 441 027 658 717 X 145-169-2 i120 e160 112 250 285 3(() o,x 141-114-1 e61 18a a .. 300 D, G, S,X 7'47-182-1 4963 202 250 a 320 370 455 SfO 020 D, S 7'47-148-1 1062 115 c90 0140 c198 354: 495 632 010 8:l 147-168-3 ... 130 AR 220 277 680 ... I 148-119-2 USS 100 c2li0 a 380 690 710 D, S, X 149-149-1 4iss 126 o52 C 210 310 474 481 Zi24 o,x 761-1"'3 173 c85 190 2(5 365 46li 500 6801 D, S 7'152-1150-1 asis2 e125 65, 12r; 205 . . . ... X ,~ 752-US0-2 123 125 ... . .. s 7,62-1,s(M 2431 133 80 ... ... 3601 430 6201 D, S Tampa not evideat 1D am763-128-1 4.831 136 220 a.7 uo 290 s pJu. m 753-129-2 4190 110 130 a. 190 2J0 300 350 44-0 D, S Tampa not evident in •mP1• I 763-139-1 121 92 124. J,16 309 383 G,X or driller'• 101, , a 429 7153-16~1 124 0 C cloli 256 370 39.5 X 7'63-168-3 101 0 C c236 2/;0 382 4-07 4-64 0 X 7'64-181..f. 120 c40 64 120 248 368 392 uo o'x ?'M-1155-2 218 120 2.50 300 435 Mo 610 o: s 2742 216 85 2.50 300 ... D, B '145-161 0109 29 72 80 370 682 658 X f.li6-13'-2, i44i 264 250 293 323 Ml X FGSWKi-714 TST-112-1 117 a IL c.55 203 324 330 37.; D,G, X 7'.67-153-2 128 c 0 150 250 ... X 7B1-116-3 26o c150 ... 0 X' P-f/T ?Bl-156-6 .... 266 C C C 0 0 c519 6607 o'x L&;c_tnterva.la between aam7.67-165-7 4255 258 14-0 200 290 425 5657 ,590 n:s 758-146-1 4634 140 60 a 155 250? D, S Tampa clay not evident in samplea or driller'• Jog. 7&9-144-2 4902 el37 JJO a 140 230 330 380 400 D, S do.
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...-0-01• -00 1601 160 2815 1 tsoD, Q i&W ii8 @IMP! &<4&@M ron1 driller's log or 11e.m7,59-1.ISS-J 160 G, X plos. .... C C c140 C calS 329 3 o-45 759-201-J 632 J32 c51 c75 103 222 314 a33 390 D, G,X 800-138-1 45&i 123 104 118 a 123 isa 2051 328 G,X 800-142-1 147 c80 132 147 & 200 244 D, G, S, X ContaminBted eamr lea. 800-143-2 864 165 140 190? 200 . . . ... D, S Not cbaraoteriatl.o-may be abaent. 800-146-1 . 3200 152 90 a 155 260 ... 4.00 465 B 800-183-1 .... 127 76 89 127 246 869 380 448 G X 800-153-3 724 119 c40 c95 cllO 217 362 392 D 1 X 800-164-3 ,11a el24: 88 120 136 ox ~1.54.-6 el4.0 60 100 130 o's SOOr169-1 8420 146 50 96 106 s~ I 801-138-2 4493 128 94 , 11 ciso isi aia ... 4i7 D, B 801-14,8:,1 151 0 0 352 X SOJ .-5 4253 147 58 101 128 270? ... 400? 4.50 X 801-154-8 148 100 o.? 170? 380? D, S V~ larp Jl&mple i.Dtemd. h form&tion top mny be ~ hJ,gher than . ah.own. Tamp& i: not evident 1D samples or dziller'a loa801-200-3 f2 core e135 18 83 129 214 ... e390 e440 D, G, S, X Lou of circwa.tion and ool lapse of bole prevented ; aampliy and electric los: Lake City 1198 Oldsmar la88, r/2 802-139-2 5098 120 100 & 140 170 270 310 D, S ,t:! 802-143-3 3307 145 146 a 190 D, S Tampa. clay .not evident iD l samples or driller'• tog. 802-144-2 6443 el68 106 ... . .. 290? 380 398 470 s J st aa.mple 290 . 802-146-2 3851 152 14-0 125 150 ... D, S Tampa clay not evideDt 1D l loiil samplea; shown on driller's i 101, 802-149-4 3033 130 05 110 143 243? ... 4287 503? D, S Larp umple intervaL 802-160-3 119 .34 89 125 ... ~• X 802-161-10 111 40 63 82 iss 315 325 ? 802-151-19 113 66 75 88 X 802-162-10 34.22 110 24 oiu 8304 427 444 607 D S . 802-107-16 4153 191 c81 c185 n'x 802-200-1 4737 130 a 90 102 240 a? 310 n: s 803-137-1 1416 164 155 0. a 200 D, S Laree sample iDterval.a. 803-143-2 5363 e138 140 a? 100 230 s Ts.mpa clay not evident in eamplea--no driller's log, 803-14.5-2 2925 155 72 D, S ... . .. ... 803-148-6 4050 133 80 a, 150 260? s 803-148-7 4215 141 807 120 130 ... D, S 803-151-11 3772 118 44 '76 98 190 D, G, S 803-153-8 128 cas 82 110 232 ix 803-153-6 3425 127 042 68 106 803-153-24 124 60 a.? 107 D, S Tampa not clearly eYident in samples, may be 10' ' I-'
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.... TA.BU 3 (Continued) oc APPROXDIATE Dr.PTH TO TOP or fORMATIO~ FOS HaWlhom ~Ol'l)Up C808 •ell Altiaude J'ormalit>o .\YOD u number tlfl&Dft (lirra1one Tampa SuwanDN C~aa.l Park Dumbe-r (W-) aurlaee only) FnrmatioD Lim.tone runr Willidion IDClia Urnatou Dacaaource Remarb D-J63--28 33j 127 -18 M? ll2 ... s Tampa ncit eld.rly eYidem from amplu,--ao drillu'a D,S loe. .... 64-34 Mf4 )38 -n ... ii. ... 330 a.so 420 803-16'-36 632-1 eJ.IJ so 82 230 D,S D-116-ll 3773 J.17 37 116 J.13 267 D, G, S s IM-138-1 1733 131 110 D,S 80&-138-2 6338 el33 HO s i'"snt •m~e at 140'DO driller a i.,._ IM-143-1 .UJ2 el33 G3 ... 200 3M s i . IOf.-UUS .... 12D -10 &I 116 348 G,X 80l-162-2 :t'IG1 118 40 D, G, S 80&-lSM mo 110 38 D, G, S ICH-114-17 :t'l&I 1-18 63 D, G, S !Ol-200-1 3838 l:U 68 fi-1 103 D,S 8 805,,163-2 3811 131 20 a 49 D, S. X 805-151-8 #1 eore e130 so IS8 60 111 276 288 3-16 D, G, S, X T& Lake Cii.Y 1028', top ldam&r I.US Ji' 806-16$-1 :t'l65 J3S 68 68 &J 180 ffl ... D, G, S, X t"' 805-1615-3 :nu J3S 62 D, G, S, X 805-1~ rr• 136 37 ... . . . . .. D, G, S m 80&-167-16 iiii 165 76 63 us 216 3M 366 X 50',resto(W-WS ! 805-18-1 '111 IJO 140 160 iir D,S 806-137-2 3201 178 180 a D,S 806-137-3 3799 HS 100 a 120 250 ... D, S 808-138-2 3876 132 C C C C C e c-1~ D ..,c 81J6;.140-1 1763 133 83 . . . . . . ... D,S 806-1'2-1 1731 139 90 a 120 D, S . IIJ8..149-6 3768 163 107 D, G, S ' Q:.155,6 _3'2,3 140 83 10! D, S SJ6:.1S6-2 3771 136 a? 63 . .. 260 430 D, G, S, X: 806--1~7 6341 e210 70 116 a 126 D,S Qul!lll'tioaable aamplQs. 807N-2 3763 136 31 m 0 70 286 D, G, S 807~ 3836 13' 26 188 303 366 D. G, S 807M: 3883 136 e-10 c75 e80 e? 290 30,5 367 D, X . Top lake City 1110'. 807-201.:.1 Z114 142 90 9,5 D,S 808-~1 3s;r7 ]37 63 a 61 D, G, S, X 808-156-1 .iii,i 138 C C J.j2 208 G X: 808-201 152 ,. 70 2-10 330 3SO -100 n's sc;,9-13&-1 2869 125 100 120 s
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---~l3o-;: -.\3~ lSO cl I I a ti. 133 22.; 2-1-1 3tJO D. G. S,X lrriell:'z:ar san•i•~P."809-136-4 2013 131 92 a a 131) 200 D,S 8CJ9:.l47-J 4%75 136 a a a 60 170 240 D.S 809-148-2 ,5015 179 12".? n " 126 23.; 257 2W D 8 809-163-3 388.'i 136 II a t"IO l.'i6 23-1 2-lfJ 305 o:x 810-1~1 113 83 112 a 114 1ST X P-l-l 810-144-1 4990 138 a a? a c:88 H9 166 198 D,G,X 810-148-1 168 C C clOI 147 201 219 248 X Wgi to 6S 810-151-2 152 a a? a 68 UM 128 157 G X 118:t:A:I 3867 ' 129 a a? a a a c:236 29-1 D. G, X Burled sinkhole 3866 129 a a? c:oo 160 236 260 322 D,G,X 811-138-3 4919 175 222 a 230 a II 2-17 300 s 812-135-1 4&12 ll6 no II a 140 D, S Tampa. clay no, indicated iD ; 813-149-1 D,G,X sompla or driller's loii5018 132 a 11! a c7o 110 t" 149 _;, 818-201-1 5352 105 a a? Ii 12-l 170 220 D, G, S, X lltl~ 6348 el50 167 a a 182 203 s i 136 a? a ll 1.;.s 160 D,G,X 81~138-1 49&i 173 a a! a a :r. lM 215 D, S 81~142-1 2133 143 a a a a a 90 s 81~157-2 3839 109 a a! II -lO 88 12.:; D, G, S. X 816:-148-1 4689 128 a a! a c79 122 1-1.5 200 D.S. X 818-151~ .... 12-1 a a? II c:-19 106 126 300 D.G,X ,,,.&i um t-4 819-140-1 5016 213 a a? a a II D. S 819-147-1 .... 128 C C C C C' c97 H-l X ti Sumter Count)": m 821~ o05l 96 a II II 0 ... , 101 136 D, G,S,X A,on Park top indieated aJ,o f by gamma-,ray lop. PaacoCount,-: D, S, X ::! 816-206-J 6350 83 21 40 81) 151 190 0 Billaborough County: 742-216-1 . 106 C' c86 . 147 e310 X loietpretation by H. z 744-226-10 G 11 302 X 1\1. Peek, (1959, fie,: 15) p . 745-215-1 145 cloS 27'.J -160 X 761-203-1 120 C 115 2iltS X ie::a,.
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20 FLORIDA GEOLOGICAL SURVEY the usage of the U.S. Geological Survey, with the exception of the Ocala Group and its subdivisions, and the Tampa Formation of Miocene age. The Florida Geological Survey had adopted the Ocala Group as described by Puri (1957), but the U.S. Geological Survey includes these strata in the Ocala Formation and the underlying upper part ( = Inglis Limestone of former usage) of the Avon Park Limestone. The Tampa Limestone, as used by the U.S. Geological Survey, is referred to as the Tampa Formation by the Florida Geological Survey. EOCENE SERIES OLDSMAR LIMESTONE Vernon (1951, p. 87, 92) and Cooke (1945, p. 40, 46) indicate that the Oldsmar Limestone probably underlies all of peninsular Florida, and that the thickness of the formation may range from 300 to 1,200 feet. They further indicate that the Oldsmar uncon formably underlies the Lake City Limestone. Four test holes in Polk County penetrate the Oldsmar Lime stone. Applin and Applin (1944) examined the samples from well 750-148-1 and placed the 670-feet interval from 1,960 to 2,680 feet I in the Oldsmar. The cores and logs from two deep exploratory 1 holes drilled near Lakeland furnish much of the geologic informa tion used in this and the following sections on stratigraphy. One core hole, about 3 miles southwest of Lakeland (well number 801200-3), was drilled to a depth of 1,842 feet. The other core hole, about 5 miles northeast of Lakeland (805-154-8), was drilled to a depth of 1,479 feet. Both of these holes terminated in the Oldsmar Limestone. The abstracted logs of these two holes are given here to aid in the discussion. Core Hole 3 Miles SW of Lakeland ( 801-200-3) Altitude of Land Surface is Approximately 135 feet above msl. MATERIAL Undifferentiated: Sand and clay. Hawthorn Formation: Limestone. Tampa Formation: Clay, blue-green. DEPTH IN FEET, BELOW LAND SURF ACE 0-14 . 14-93 93-136
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REPORT OF INVESTIGATION NO. 44 21 Core Hole 801-200-3-Continued DEPTH IN FEET, MATERIAL BELOW LAND SURFACE Suwannee Limestone (start core at 139 ft. 3 in.) : Chert, dark gray, very hard; re placed limestone, with pre-chert solutional cavities up to 2 inches, filled with cream limestone containing Sorites sp. Drilling water circulation lost at 138 feet. 135-142 Unidentified: Not cored from 142 to 652; all drilling water circulation lost, no cuttings re turned. Avon Park Limestone: Open cavern. Sand and mud (driller's interpretation), probably cavern-fill, very soft. Open cavern, casing slipped to bottom of hole. Casing set by water-jetting only; probably sand and mud cavern-fill, very soft. Casing set by water-jetting and casing ro tation only; probably extensive honeycomb and/or sand and mud cavern-fill, very soft. In Avon Park Limestone ( cored from 662 ft. 11 in. to total depth 1,842 ft.): Dolomite, replaced limestone, dark brown, dense, broken and highly fractured (some re-cemented). (See figure 4.) Dolomite, as above, with solution cavities up to 2 inches, and one open vug ( after gypsum) containing small amounts of loose brown dolomite sand. Cavities are de veloped along fractures in cavern collapse rubble. Dolomite, as above, cavern-fill developed in dolomitized collapse rubble (fill). Dolomite, as above, badly broken to resem ble coarse gravel. May include a continua tion of pre-dolomite collapse zone above. Dolomite, as above, a collapse rubble of angular dis-oriented inclusions in finer grained matrix. Cavities developed and partly filled with brown dolomite sand ( ?) . Dolomite, as above, badly broken in zones. Dip-slip faulting or slumping, and repeti tive thin beds due to overriding thrust. 670-673 684-685 686-703 703
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22 FLORIDA GlmLOGICAL SURVEY Core Hole 801-200-8-Continued MATERIAL Thrust fnult cutting n chert nodule. Slick Jcnslides on nearly horizontal bedding plane th rust. Dolomite, as above, locally broken and fractured. A few small solution cavities de veloped ( vugs after gypsum?) Dolomite, ns above, a dolomitizcd rubble. AngulAr inclusions up to 1 inches, in finer grained matrix, have random orien tation. Believed of coJJapso origin, but pos8tbly a prc-lithiftcation sedimentary rubble. Dolomite, as nbovc, bndly broken nnd frnc turcd in some zones. Dolomite, ns above, collapse rubble, angu lar inclusions up to 2 inches in hetcrogc nous matrix, with random orientation of inclusions. Dolomite, as above, massive and dense to badly broken in zones, occasional solution cavity up to :,,~ inch. Clay. a sedimentary rubble. Limestone, soft, chalky; some flnu to very fine honeycomb development and occasional cavities up to 1 inch. Limestone, soft to hard in zones, solution tubes up to ~-l inch diameter nnd fine honeycomb development. Limestone, dolomitic?, hard with fine hon eycomb development. Limestone, moderately soft, with ~ubes and cavities up to inch. Lake City Limestone: Limestone, soft to hard, chalky zones, low permeability with occasional fine honey comb. abundant nodules and nests of nod ules of gypsum altered from anhydrite. Abundant nnd general impregnation by selenite. Some open pore-space and molds, but not common. Dolomite, replaced limestone, very hard, general selenite impregnation, but some open pore spaces, small tubes and cavities, gypsum nodules altered from anhydrite. Fractures, vertical to high-angle, in lower part are re-cemented by selenite. DEPTH IN FEET, BELOW LAND SURF ACE 703703-722 722%-726 726 1 /J-742 742-746 746-778 778-780 780-876 876-951 951-1,068 1,068-1,128 1,128-1,451 1,461-1,688
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REPORT OF INVESTIGATION NO. 44 23 Core Hole 801-200-8-Continued MATERIAL (Con't) DEPTH IN FEET, BELOW LAND SURFACE 0hlsmnr Limestone: Dolomite, hnrd, pore spnce as molds and fine honeycomb, generally selenite impreg nated; gypsum nodules altered :from anhy drite, some selenite cemented fractures. Some thin zones of dolomite sand ( ?) Dolomite, ns above, dolomite snnd ( ?) zones more numerous and thicker with very high porosity; a few scattered open vugs after gypsum (?) excavation. Gyp sum nodules altered from anhydrite. Sele nite impregnation of dense dolomite zones. Dolomite, as above, abundant nests and scattered gypsum nodules altered from an hydrite; selenite ns impregnntion nnd frac ture cement. Anhydrite, white, massive, single bed. Dolomite, ns nbove, scattered anhydrite and gypsum nodules, scattered occurrences of dolomite sand (?), extensive selenite im pregnation of massive dolomite, nnd post dolomite fractures. 1,588-1,688 1,688-1,746 1,746-1,812 1,812-1,816 1,816-1,842 Core Hole 5 Miles NE of Lakeland ( 805-154-8) Altitude of land surface is approximately 130 feet above msl. Undifferentiated: Sand and clay. Huwthorn Formation: Limestone. 1'ampa Formation: Clay, blue-green. Suwannee Limestone: Limestone, detrital, very soft, chalky, little evidence of solutional activity. Ocala Group Crystal River Formation: Limestone, soft, granular to very chalky, little evidence of solutional activity. Williston Formation: Limestone, soft to moderately hard, granu lar, local dolomitized zones, some solutional removal of calcite matrix. 0-60 60-68 68-60 60-161 161-276 276-286
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24 FLORIDA GEOLOGICAL SURVEY Core Hole 805-154-8-Continued Inglis Formation: Limestone, granular, soft to hnrd, locally dolomitized, note solutional removal of ce ment and fossil molds, fine solution al tubes, and local honeycomb. Avon Park Limestone: Limestone, hard to soft, granular to chalky, visible porosity moderate to very high in granular zones. Dolomite, replacement of limestone, very hard and dense; solution tubes 1 inch x 1 /4 inch diameter. (First such features noted.) Lost drilling water circulation. Dolomite, replacement of limestone, very hard; dense to granular, low to very high visible porosity. Lost drilling water circulation. Fine honeycomb. Dense, badly broken, as dolomite 0 gravel.'' Dense, thin bedded, with zones of fine honeycomb. Badly broken, as gravel, some solution along fractures. Badly broken, as gravel, in zones. Collapse rubble zone; angular inclu sions up to 4 in. Random orientation, one 3 in. piece is thin-bedded with bed ing-tipped vertical, matrix fine-grained and thin bedded. Collapse rubble. angular, badly broken. Dense, badly broken. Collapse rubble. very angular inclu sions up to 2 in. Random orientation, yellow thin-bedded inclusion tilted with bedding at high angle to core. S-Ome sol ution along fractures through interval. This interval may be essentinlly con tinuous from 574. Dense, badly broken. Limestone, moderately soft, very fine hon eycomb developed. Limestone, soft to moderately hard, some small tubes and fine honeycomb. At 685 feet first open vug from removal of gyp sum alteration of anhydrite nodules. DEPTH IN FEET, BELOW LAND SURFACE 286-846 346-444 444 1 h-449, 612621-615 629534-536 638-542 642-552 652-563 656-664 566-667 574-575 576-578 678-688 597-610, 62l1h-628 623-685
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REPORT OF INVESTIGATION NO. 44 25 Core Hole 805-154-8-Continued Limestone, collapse 1ubble, middle 1 foot dolomitized. Post dolomite f1.•actu1es. Collapse rubble continues from 695; core shows old cave1.n wall and fine-grained fill with larger inclusions. Badly broken in lowe1 part; fine second-stage solution hon eycomb developing in dolomite. Dolomitized collapse 1ubble with post dolomite fractures. Limestone, generally chalky and soft to mode1ately hard in thin local partially dol omitized zones. Visible porosity low to moderate due to fossil molds and fine hon eycomb development. Numerous large (to 2-in.) irregular vugs 1esulting from so lutional excavation of gypsum alte1ed from rubble of anhyd1ite nodules. Abundant cal cite crystals in vugs below 879 feet, and a few quartz crystal growths noted. Oc casional silicified clay beds a few inches thick. Lost dl'illing water ch-culation; 1egained and partial loss of circulation again at 796 feet. Limestone, chalky, very soft to moderately soft, heavy selenite impregnation of pores and molds. Nodules of gypsum ( after an hydrite) up to 1 1 h in. Lake City Limestone (1,028-1,4451,6): Limestone, chalky, soft; contains irregular, rounded, nodules of gypsum altered from anhydrite rubble. Profuse selenite impreg nation of pore space, but some small open solutional cavities and fossil molds noted. Visible porosity generally low. Limestone, dolomitic, with gypsum as above. Dolomite, 1eplaced limestone, hard, crystal line. Gypsum nodules as above, selenite im pregnation, and some small open pore space. Dolomite, as above, with small cavities con taining dolomite-sand fill. Gypsum as above. Limestone, dolomitic, moderately soft to moderately hard, low porosity. Selenite im pregnation and gypsum as above. Occa sional open vug after gypsum. DEPTH IN FEET, BELOW LAND SURFACE 695-698 698-704 716-717 717-1,016 7851,015%-1,028 1,028-1,295 1,295 1 h-1,3741h 1,374-1,386 1,386-1,3921h 1,392-1,445
PAGE 36
26 FLORIDA GEOLOGICAL SURVEY Core Hole 805-154-8-Continued DEPTH IN FEET, BELOW LAND SURFACE Oldsmar Limestone (1,446 -1,470): Limestone, dolomitic, moderately hard. Small gypsum nodules as above, n few smnll vugs after gypsum. Some selenite impregnation and fine honeycomb. Dolomite. replaced limestone, dunse, hnrd; scattered gypsum ns above, and some flcle n ite impregnation: fine honeycomb zoncs and rare small open vugs after gypsum. 1,446 -1,459 1,469-1,479 On the basis of the major change in character of the electric and gamma-ray logs, and lithology, the lower 331/~ feet (1,4451/i 1,479 feet) of well 805-154-8 and the lower 268 feet (1,688-1,846 feet) of well 801-200-3 are tentatively designated as Oldsmar Limestone. In wellR 801-200-3 and 805-154-8, the Oldsmar is a grayish-tan to brown, very hard, finely crystalline, highly dolomitized, gypsi f erous limestone. Generally, dolomitization appears to follow bedding planes and is inter-bedded with a few soft, calcareous zone8. Color of the formation becomes more grayish downward \vith increasing amounts of disseminated peat. The f ormntion contains rubble-beds which are generally less than a foot thick, which were formed before the sediments were firn1ly cemented and lithified. These are interpreted as bottom sediments which have been broken up by wave action while in n semi-plastic state, then re-deposited and cemented. Such changes may reflect storm waves of greater than normal proportions. The formation also contains sequences of thin, individual graded-beds, each bed being only 1 or 2 inches thick. These graded-beds, and the rubble-beds, indicate rapidly changing sedimentary conditions in a relatively shallow sea or embayment. Such changes may hme been short-lived and of generally small magnitude. Thick peat cumulations at the top of the formation were interbedded with rubble-beds. Other rubble-beds were found throughout the forma tion. Further study of such features in these two wells will pro vide more information about the environment of deposition of tl , e formation. In wells 801-200-3 and 805-154-8 in the Lakeland area, the co1: tinuous cores from the Oldsmar Limestone contain considerabie amounts of anhydrite, gypsum, and selenite, a clear crystalli11e variety of gypsum. A solid bed of anhydrite was encountered fro10
PAGE 37
REPORT OF INVESTIGATION N 0. 44 27 1,t 12 to 1,816 feet in well 801-200-3. With this exception, the an i1ydrite and gypsum in the Oldsmar occurred as rounded irreg ular nodules that are several inches long in the greatest dimension. Tlie nodules were not apparently oriented and were scattered as individual nodules or deposited in clusters that seldom exceeded a foot in thickness. The nodules were originally anhydrite and all but a few in the lower part of the formation have been partly or completely altered to gypsum by varying degrees of hydration. Most of the gypsum nodules contain a large core of unaltered an hydrite. This alteration is accompanied by a 30-50 percent in crease in volume (Pettijohn, 1949, p. 356), and the increase was evidenced by the fracturing and filling of adjacent limestone Rtringers and walls. The evaporites usually originate as bedded deposits in closed shallow basins. The occurrence here as separate nodules is interpreted as being the rubble of originally bedded de posits which have been destroyed by wave action. The size and shape of the nodules suggest that the rubble was transported a relatively short distance before re-deposition. Such an interpreta tion is consistent with that of the pre-lithification sedimentary rubble beds mentioned previously. Selenite occurred in much of the formation as an impregnation of pore spaces and as fracture filling r or cement. The selenite probably represents a further alteration, 1 or solution and precipitation, of gypsum. Several small nodules of gypsum have been completely dissolved leaving open vugs in the roek. These vugs have intricate irregular walls like those enclosing the nodules cut by the drill, and there can be no doubt as to the origin of the vugs. In the core samples from wells 801-200-3 and 805-154-8 the contact of the Oldsmar with the overlying Lake City Limestone is indefinite and appears to be a disconformable zone, rather than an erosional unconformity. The disconformable zone appears to lw about 30 feet thick and contains large quantities of peat or low-grade lignite. The peat is thought to be of marine origin and tu represent a long period of very sha11ow water conditions and Iii tie deposition. The presence of gypsum and anhydrite nodules in the disconformable zone and subjacent beds of the Oldsmar indi e.: te the absence of fresh water erosion or circulation of fresh r ound water after deposition. Excellent correlation of the disconf ormable interval was made b ' gamma-ray logs of the two wells, which showed marked in c eases in radioactivity in the thick peat zone at the top of the f. ,rmation. The disconformable zone appears to be unfossiliferous,
PAGE 38
28 FLORIDA GEOLOGICAL SURVEY but this may be partly due to intense dolomitization and resultant destruction of fossils. The peat occurs as beds from 6 to 14 inches thick, as thin seams and bedding-plane films, and as disseminated flakes. Only a slight change in color and lithology may be noted in ' passing downward from the Lake City Limestone into the Oldsmar Limestone. In wells 801-200-1 and 805-154-8 the formation has very low visible porosity and permeability. Both porosity and permeabilitJ seem to increase in fractured dolomitized zones, but some of these zones have been partially re-cemented or filled with selenite. The presence of selenite, S:,rypsum, and anhydrite throughout the for. mation clearly shows that there has never been a significiml amount of fresh ground water in it, because these minerals ar1 soluble and would have been removed. LAKE ClTY LIMESTONE The Lake City Limestone is penetrated by relatively few wells in this county, and only four wells are known to pass entirely through the formation. According to Cooke (1945, p. 46), the formation underlies all but the northwestern part of the state. Samples were not collectcli from this formation in well 811-149-1. According to Cooke (1945, 1 p. 48), the Lake City was encountered in well 750-148-1 at a depth of 1,540 feet, and it extends to a depth of 1,960 feet. i In well 805-154-8 a selenite and peat ( ?) replacement of Dictyoconus amc-ricanus, the index fossil of the Lake City, WHR recovered from the core at a depth of 1,028 feet. Identificatiou wa~ based on the internal cell structure as illustrated by Applin and Jordan ( 1945, p. 136, fig; 2). Other specimens were observed in the core at this depth. The electric log of this well shows a decrease in both resistivity and self-potential at a depth of 1,028 feet in a moderately s< 1 ft, clayey, chalky zone of low visible porosity. The top of the forna tion is the ref ore placed at 1,028 feet in this well, and the forna tion continues to a depth of 1,445 feet. The formation top on this f!lectric log correlates very closely with the electric log of nearby well 807-154-4 at a depth of 1,110 feet. This depth (l,J 10 feet) also coincides with the first occurrence of chert and gyps mi in the well according to a log prepared by E. W. Bishop of ... he Florida Geological Survey ( FGS W-3883,. July 17, 1956) . Bis} op (op. cit.) designates the interval 1,110-1,198 feet as Avon Pirk
PAGE 39
REPORT OF INVESTIGATION NO. 44 29 Li?nestone. In well 801-200-8 the Lake City Limestone is identified in the interval from 1,198 to 1,588 feet by correlation of electric and gamma-ray logs with those of well 805-154-8. On the basis of tlwse three wells, the thickness of the Lake City Limestone ranges from 417 to 420 feet in Polk County. In wells 801-200-8 and 805-154-8 the Lake City Limestone is a white to cream, moderately soft to hard, chalky limestone. The lower 75 to 130 feet of the formation contains finely crystalline, highly dolomitized zones which appear to follow bedding planes. The formation contains abundant peat films on bedding planes. Scattered chert nodules occur in the upper part of the formation and few thin apparent chert "beds" in the lower part of the for mation may actually be small nodules or lenses. All of the chert appears to be of secondary origin as a replacement of limey sedi ments. Pre-lithification sedimentary rubble-beds, generally a few inches thick, are abundant throughout the formation in both wells 801-200-3 and 805-154-8. In wells 801-200-3 and 805-154-8 the Lake City Limestone con tains abundant anhydrite, gypsum, and selenite. The nodular mode of occurrence of these minerals in the Lake City is the same a~ that previously described in the Oldsmar Limestone. The same interpretation of origin and alteration, from original bedded an hydrite to nodular gypsum and selenite, also applies to the Lake City. However, the Lake City in these two wells does not contain bedded, or unaltered nodules of anhydrite. In general, the anhy drite cores of the nodules decrease in size upward and completely altered nodules of gypsum are common. Individual nodules reach as much as 12 inches in their greatest dimension. Selenite im pregnation of pore spaces, small solutional tubes and cavities, small vugs, and fractures occur throughout much of the forma tion. Open vugs, generally less than 1 inch in diameter, resulting from solutional removal of anhydrite-gypsum nodules occur throughout the formation. These are relatively few in number, but are more numerous than in the Oldsmar. Cooke (1945, p. 46) and Vernon (1951, p. 92, 99) indicate that t '1e contact of the Lake City and the overlying Avon Park Lime ~ one may be unconformable. In the cores from wells 801-200-3 ,: 1d 805-154-8 the contact zone is not obvious. In well 805-154-8 rrpsum nodules occur at 1,038 feet, 10 feet below the contact. In ,, ell 801-200-3 gypsum nodules occur throughout the contact zone r 1d adjacent beds. The occurrence of gypsum nodules and the con t nuity of lithology strongly suggest that the contact is transi
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Pages Missing or Unavailable
PAGE 41
32 FLORIDA GEOLOGICAL SURVEY and their significance will be discussed in more detail in the sec . tion on solutional features. The Avon Park contains anhydrite-gypsum nodules in the sanw mode of occurrence as has been previously described in the Olds mar and Lake City Limestones. The same interpretations of origi11 and alteration, from original-bedded anhydrite to nodular gypsun1 and selenite. ~tated for these earlier formations is also applied to the Avon Park. However, in wells 801-200-3 and 805-154-8 the Avon Park does not contain unaltered anhydrite, and it now con t:lins eonsiderably less total anhydrite, gypsum, and selenite than the two underlying formations. In well 801-200-3, the cored we1l ~outh\ve~t of Lakeland, the Avon Park contained scattered gyp sum nodules and clusters and selenite impregnations only in the lo\ver 70 feet (1,128-1,198). In well 805-154-8, northeast of Lake land. the Avon Park contained such deposits only in the lower 13 feet ( 1.015-1.028). In both wells the gypsum nodules contained cores of anhydrite. There is no doubt that the Avon Park once contained a much greater amount of the evaporate nodules. In well 805-154-8 many open vugs with irregular, concavely rounded walls, occurred at depths of 685 to 885 feet. It seems clear that these vugs result from the complete solutional removal of evaporite nodules. The open vugs were scattered and sparse in number from 885 to 1,015 feet. Only a few vugs were found in the cores from well 801-200-3 and these occurred from 829 to 1,128 feet. The Avon Park Limestone contains numerous thin, porous, gr .. 1nular. sand-like zones of dolomite, the origin of which is un kno\vn. There are several suggested origins that may be possible: ( 1) Some zones may be a depositional dolomite-sand in solutional cavities; (2) some zones may be an ultra-fine honeycomb de veloped along fractures and other openings by solution; and (3) some of the zones may be the result of precipitation of ultra-fine dolomite crystals. Such zones are also found in the dolomitizerl zones of the underlying Lake City and Oldsmar Limestones. The formation also contains, particularly in the ]ower part, numerous chalky or clayey zones; some thin, well-defined calcare ous clay beds; and abundant peat as thin films on bedding planes. There are al.so chert nodules, apparent chert beds, and diffused silicified zones. Vernon (1951, p. 99) states that both of the formational con tacts are erosional unconformities. The present studies of cores from wells 801-200-3 and 805-154-8 in the Lakeland area, and
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REPORT OF INVESTIGATION No. 44 33 1any sets of cuttings indicate that the contact in Polk County is . nconf ormable. The lower few feet of the overlying Inglis For , .1ation generally contain pieces of dark, granular rubble up to j-inch diameter and abundant eroded Dictyoconu,S sp. and , 'oskinoUna sp. fron1 the Avon Park. This is interpreted as weathered Avon Park Limestone, eroded and re-deposited in the t•arly stages of Inglis deposition and hence an unconformable con tact. Permeability of the formation ranges from very low in some of the clayey or chalky zones to extremely high in cavernous zones. The visible porsity and permeability of the formation, as a unit, is high and it is the greatest water-producing unit in the F'loridan aquifer in Polk County. Local areas in which the for mation as a whole is of low permeability have been encountered, but these are relatively few in number. OCALA GROUP In recent years the Florida Geological Survey has subdivided the rocks formerly grouped within the Ocala Limestone. Vernon (1951, p. 113-171) divided this sequence of rocks into the Ocala Limestone (restricted) and the Moodys Branch Formation. He divided the Moodys Branch Formation of his usage into two parts. The lower unit was named the Inglis Member, and the upper unit was named the Williston Member. Puri (1953a, 1957) gave the name Crystal River Formation to Vernon's restricted Ocala Limestone and gave formation rank to Vernon's Inglis and Williston Members of the Moodys Branch Ii'ormation. The Crystal River, Williston, and Inglis Formations are now referred to as the Ocala Group by the Florida Geological Survey and the name Moodys Branch Formation is no longer used in Florida. The northeastern half of Polk County is underlain by the Ocala Group as shown in figure 5. Inglis Formation 'I'he Inglis Formation underlies almost the entire county except in local areas in northeastern part and is a white to cream to dark brown, generally hard to very hard, granular, partially to highly dolon1itized, highly fossiliferous limestone with some local soft chalky zones. In the area lying generally north and west of Polk City, the formation is highly dolomitized, very hard and contains many sand-filled solutional cavities. In the central part of the county the formation has a relatively
PAGE 43
34 FLORIDA GEOLOGICAL SURVEY uniform thickness of 35-45 feet. In well 821-202-8 in Sumter County, northwest of Rock Ridge (fig. 4), the Inglis is 29 feet thick. This well is located along the crest of the major structural feature in the area. In well 805-154-8, northeast of Lakeland, the Inglis is approximately 50 feet thick. It thickens slightly along the e..meme western part of the county to about 45-50 feet. In the southeastern part of the county the Inglis is as much as 95 feet thick. r 'IIO ! ..,. " . .. . . .,. ' . i .i I \ U C 1 h \, '----\ r. nu "i 1 Y .. , . .. , J. (_ . . . '~..... . to' ., . ... . ... -t:;.~, .. ...._;_..!:~L~ ... -.. ,:::.~"-',;.. . . _. , _...,. w . .......1r~~:~~ ;.--~'•-:--. ___ ._ ........... --Figure 5. Geologic map of the pre-Miocene formations. The Inglis is the uppermost limestone in extreme north eastern Polk County due to erosion of the overlying beds along the crest of a structural high. The Inglis conformably underlies the '\Villiston Formation, and unconformably overlies the Avon Park Limestone. (Vernon, 1951, p. 212). In well 805-154-8 the Inglis appears to have low to moderate porosity in the upper part of the formation. Moderate to high visible porosity in the lower part of the formation is due to the
PAGE 44
REPORT OF INVESTIGATION No. 44 35 emoval of the calcite cement and matrix in the granular and !ossiliferous zones. The Inglis is one of several formations usually :lenetrated by water wells in this area. Locally it may be a good producer due to cavernous conditions and/or its generally granu iar texture. However, wells are not usually drilled for the purpose of obtaining water from this formation. Williston Formation The Williston Formation is a white to cream to brown lime stone, and is a generally soft, coarse, coquina of foraminif era, set in a chalky calcite matrix. The lower 5-15 feet are usually harder than the rest of the formation due to dolomitization. The formation has moderate visible porosity. The Williston is gener ally less highly dolomitized than the underlying Inglis Formation. The formation underlies most of the county with a thickness which ranges from 10 to 100 feet, and averages about 30 feet. These thicknesses are based principally upon electric-log determi nations. In extreme northeastern Polk County the formation is missing, having been removed by erosion, and may be missing from other local areas near the crest of the structural high. Vernon (1951, p. 143) states that the formation lies con formably between the Inglis and the overlying Crystal River Formation. The lower contact is marked by a distinct Jithologic change, but the upper contact is transitional and very difficult to define. The Williston is one of several formations usually penetrated by water wells in this county, and it is believed to contribute some water to wells. The general character of the formation (soft, coquinoid, and chalky matrix) results in a lower porosity and permeability, as compared to the more productive underlying formations. Crystal River Formation In the subsurface the Crystal River Formation is a white, gray, cream, or tan, generally very soft, co arse, granular, lime stone of very high purity which contains great numbers of large f oraminifera in a chalky carbonate matrix. Locally it may contain thin hard dolomitized beds or zones which are controlled by bedding. The Crystal River is easily recognized from the abundance of disc-shaped foraminifers of the genus Le;pidocyclina. In some of the species the disc has a saddlelike shape. The formation com
PAGE 45
36 FLORIDA GEOLOGICAL SURVEY monly is referred to as "Ocala," "shell," or "limeshell" by local drillers. The formation ranges in thickness from 80 to 125 feet in an east-west belt across the county between Lakeland and Ft. Meade. South of this belt it thickens gradually southward to 150 feet, possibly even thicker locally. North of the belt, it ranges from 30 to 60 feet in thickness due to erosion and has been entirely removed from broad areas lying northeast of Polk City. The for mation has been removed by erosion in the vicinity of eastern \\"inter Haven, where the Williston Formation appears to be di rectly overlain by the Suwannee Limestone. Both the Crystal River and '\Villiston have been removed by erosion from the vicinity of Haines City and the Inglis is directly overlain by the Suwannee Limestone. The Crystal River is the uppern1ost Limestone in the northern part of the county due to erosion of the overlying Suwannee and younger formations. Along the crest of the structural high area in northwestern Polk and adjacent parts of Lake and Sumter counties, the Crystal River Formation is at, or within a few feet of the surface over an area of approximately 100 square miles. This outcrop area has not been previously mapped or described in any literature. The outcrop area was mapped and studies in a reconnaissance by E. W. Bishop, geologist, Florida Geological Surveyp and the author in April 1957. The results are discussed here with the permission of Mr. Bishop.a Throughout the area of surface exposure the limestone is silici fied by replacement with hard, dark gray to white chert. In these exposures the fossil content has been generally destroyed by the replacement, but locally small concentrations of Lepidocyclina ocalana ,vere found. Lepidocycl-ina ocalana is a diagnostic fossil of the Crystal River and is usually abundant in the formations. Numerous echinoids were observed in many parts of the out crop area. In some locations the echinoids were found adjacent to occurrences of Lepidocyclina ocalana. More than 40 specimens of echinoids were collected, and they appear to represent a single species. Nine of the best specimens from the area of outcrop, and one from a limestone pit at Lacoochee, Pasco County, were identified as Rhyncholampas (Cassidulus) gouldii (Bouve) by ~Ir~ Porter Kier, Associate Curator, Division of Invertebrate Paleontology and Paleobotany, U.S. National Museum: 1 Ca,ssidu" Personal communication, E.W. Bishop, December 12, 1960. Personal communication, Porter M. Kier, April 10, 1961.
PAGE 46
REPORT OF INVESTIGATION NO. 44 37 . us gouldii (Bouve) is a diagnostic fossil of the Suwannee Lime ,tone of Oligocene age, which normally overlies the Crystal River. The echinoids are preserved as filled molds, the filling being . i miliolid-rich granular limestone. In one such echinoiq, a speci men of Dictyoconus coolcei was found and, although this fora minif er is diagnostic of the Avon Park Limestone, it is also fre quently found in the Suwannee Limestone. Because of the observed association of Suwannee and Crystal River fauna the outcrop area is interpreted as being the . eroded remnant of the original contact zone of the two formations. Such interpretation thus places the thickness of the Crystal River on the crest of the Ocala uplift at 60 feet or less. Only one outcrop of slightly calcareous limestone was observed. A well in the outcrop area in southern Sumter County, 821202-3, penetrated 72 feet of the Crystal River Formation. Surrounding the area of outcrop is a broad belt of boulders and isolated boulders and cobbles. The closeness of the formation to the surf ace is inf erred by the presence of many silicified and sparsely fossiliferous boulders and cobbles in the spoil piles or in the bottoms of the extensive shallow drainage canals in the area. Many of the boulders and some of the outcrops showed extensive solutional erosion prior to silification. It is evident that some of the boulders were origina11y geodes or parts of small caverns that were armored through replacement by, or deposi tion of, gray to white chert, while the main body of limestone remained unaltered and soluble. Subsequently the soluble lime stone portions of the formation were removed by chemical and/ or mechanical erosion, during exposure at land surface, leaving the resistant silicified solutional features. Several boulders con tained solutional cavities lined with banded, botryoidal, amor phous chalcedony, and geode-like, clear, quartz-crystal growths. The Crystal River, according to Vernon (1951, p. 160) lies conformably upon the Williston Formation and is unconformably overlain by the Suwannee Limestone of Oligocene age, or by younger unconsolidated clays and sands. In well 805-154-8 the Crystal River is 124 feet thick and has low to moderate visible porosity and permeability. Small incipient solutional tubes and cavities were observed in the in terval from 182 to 224 feet. Cores were not taken from this forma tion in well 801-200-3. The yield of wells terminating in the Crystal River Formation is considerably less than those drilled into the Avon Park Lime
PAGE 47
38 FLORIDA GEOLOGICAL SURVEY stone, due to the very soft, chalky matrix. The yield of such a well can usually be increased by deepening the well into one or more of the underlying formations. The formation will generally produce a sufficient quantity for domestic supplies. OLIGOCENE SERIES SUWANNEE LIMESTONE The Suwannee Limestone is white, cream, or tan, generally very soft, granular, detrital limestone which is generally very pure. Locally, however, it contains a small amount of fine quartz sand as disseminated grains. It contains abundant bryozoa, small mollusca, and large echinoids. Local drillers refer to it as the Hcoquina." In some places the upper surface, and/or a zone near the middle of the formation, is replaced by dark-brown or gray chert which commonly ranges from a few inches to a few feet thick. The greatest thickness of chert encountered, or reported, in the county was 10 feet in well 803-156-11 in Lakeland. The chert zone occurred from 208 to 218 feet, near the middle of the for mation. The area of Polk County underlain by the Suwannee Lime stone is shown in Figure 5. In well 805-154-8 the formation is 91 feet thick and contains thin hard dolomitic zones from 73 to 75 feet. The formation con tains some small solutional tubes and cavities which are lined with small calcite crystals. The lower portion of the formation is chalky and less granular than the upper part. The Suwannee in this well has a moderate to low visible porosity and permeability. The lower few feet appear to be an indistinct pre-Iithification rubble zone, and contain films of black peat along bedding planes. The thickness of the Suwannee in well 801-200-3 is unknown due to loss of cuttings and circulation at 136 feet. In this well, however, the upper 3 feet of the formation was cored, and is a complete replacement by gray chert. The silicification preserved in detail many solutional cavities in the limestone. Some of these cavities contained a filling of cream colored sandy limestone, which contained a number of Sorites sp., and which is tentatively identified as limestone of the Hawthorn Formation of Miocene age. This clearly establishes one reason for the finding of this particular fossil, as reported by Stewart (1959, p. 22), in what might otherwise be considered as slightly sandy Suwannee Lime stone.
PAGE 48
REPORT OF INVESTIGATION No. 44 39 Thickness of the Suwannee generally ranges from 80 to 120 leet in the central and southern parts of the county. It thickens rather abruptly from 70 feet in a well southwest of Lakeland (759-201-1), to 195 feet in a well in south-central Hillsborough County (746-209-1). In the northern part of Polk County the formation thins considerably due to both depositional and erosional thinning, and is absent in much of the northern and eastern parts of the county (fig. 5). In several sets of well cuttings the Suwannee Limesto;ne con tained some fossils that are diagnostic of the Crystal River For mation. Some of these samples also contained a few specimens of the Suwannee foramanif er Rotali,a mexicana, which is not a durable fossil. Such rocks, though containing predominantly Crystal River fossils, are interpreted as Suwannee Limestone. They indicate local erosion and re-deposition of Ocala rocks during deposition of the Suwannee. An example of such deposits .was found in the upper 36 feet of limestone in well 800-142-1. The yield of wells terminating in the Suwannee Limestone is considerably less than those in the Avon Park Limestone, but is generally greater than the yield of wells in the Crystal River Formation. The Suwannee furnishes adequate supplies for domes tic and small irrigation wells, and it is widely used for these purposes. MIOCENE SERIES The correlation of the formations of Miocene age in Florida and adjacent states has long been a major geologic problem. Re cently great strides have been made with this problen1 in the Florida panhandle by Puri (1953b). Major problems still exist, however, in the peninsular part of the state. Reports by Bergen dahl (1956, p. 69-84), Cooke (1945, p. 109 ff), Vernon (1951, p. 178-186), Puri (1953b, p. 15 ff), and others contain sun1mar ies of the problem. In recent years the Miocene and younge;r deposits in the cen tral part of the peninsula have been studied by many geologists of the U.S. Geological Survey. Some of the findings are reported by Cathcart and McGreevy (1959), Ketner and McGreevy (1959), Carr and Alverson (1959), Altschuler, Jaffee, and Cuttitta (1956), Altschuler, Clarke, and Young (1958), Altschuler and Young (1960), and others. With these recent contributions some of the questions regarding the Hawthorn and Tampa Formations may have been resolved, but in the case of the limestone units
PAGE 49
40 FLORIDA GEOLOGICAL SURVEY of these formations, which are widely used ground-water aquifers , a basic practical problem of identification and delineation still e..xists. The chemical and lithologic constitution (Carr and Alverson, 1953, p. 175 ff) of the limestone units of the two formations is identical for field mapping purposes. The fossil fauna is largely mollusca which are not individually diagnostic of either forma tion, and faunal assemblages are only generally diagnostic of the early and middle Miocene ages presently assigned to the Tampa and Hawthorn Formation respectively (Vernon, 1951; Puri, 1953b; Espenshade and Spencer, 1963). Identification of . these formations is made even more unlikely in Polk County because of dolomitization and because most of the geologic work must be done from well cuttings, in which large mollusca molds are rarely recovered intact. Sorites sp., common to the Tampa but not diag nostic of it, has not been found in known exposures of the Haw thorn, but has been found in well cuttings in both typical Suwannee and Hawthorn lithology, thus complicating the prob lem further. A-rcha-ias floridanus, a foraminifer commonly ac cepted as diagnostic of the Tampa, has not been found in well cuttings in this area. TAMPA FORMATION Cole ( 1941, p. 6) identified the Tampa between the depths of 117 and 180 feet in a well 4 miles north of Lakeland (805-157-15) at the Carpenter's Home, on the assumption that the Tampa Formation underlies all of Polk County, and on the basis of general lithology, and an interpretation of fossil evidence. In his diagrammatic illustration of the well (op. cit., p. 5, fig. 2) he also includes the interval of 180 to 250 feet in the Tampa. This well was in use during the entire course of the present in vestigation, and exploration of the well was not possible. How ever, on the basis of an electric log obtained in well 805-157-16, approximately 50 feet west of the well described by Cole, the in terval 117-250 feet was determined to be the Suwannee Limestone. Cooke (1945, p. 182) states that the Tampa probably under lies all of Polk County south of Lakeland. Vernon (1951) does not discuss the Tampa Formation in his description of strati graphic units. Cathcart ~nd McGreevy (1959, p. 228) found the Tampa Limestone in western Polk and adjacent parts of other counties, and report it to be a sandy, clayey, limestone containing abundant chert fragments and very few phosphate nodules. They
PAGE 50
REPORT OF INVESTIGATION No. 44 41 tate that the limestone is interbedded with clay and sandy clay, : nd describe a locally developed residual mantle of green calcare < us clay which contains chert and limestone fragments and a j ew phosphate nodules. Ketner and McGreevy ( 19 59, p. 59-65) consider the Tampa Limestone to consist of three units, only two of which are present in Polk County. Their upper, so-called "phosphorite unit" lies north of this county and does not occur in the area of this investi gation. In northern Polk, according to Ketner and McGreevy, the Tampa is represented by a limestone unit and a clay unit. The clay unit consists of "greenish-gray to brown clay containing well-sorted, very fineto fine-grained quartz sand. Sand ranges from 5 to 80 percent, averaging about 35 percent." They further state that the clay unit "apparently grades into the limestone unit of the Tampa about where the limestone unit of the Haw thorn Formation appears." Their limestone unit of the Tampa is described from an exposure in the Tenoroc Mine of the Coronet Phosphate Co., northeast of Lakeland, as being "fossiliferous, yellow, somewhat soft, clayey, and sandy. The sand consists of very fineto fine-grained quartz and sandto pebble-sized, rounded, polished phosphorite nodules." They do not describe the areal extent of the limestone unit, but identify it in two drill holes. Carr and Alverson (1959, p. 14-33) present the most complete studies and discussions of the Tampa in recent years and extend the formation eastward from Tampa Bay as far as central Polk County. According to these authors, the Tampa is a white to light yellow, soft, moderately sandy and clayey, locally phosphatic, finely granular, and locally highly fossiliferous limestone. They state that both marine and fresh water limestones are present, and that both upper and lower contacts of the formation are erosional unconformities. Further, they state that limestone com monly interfingers with calcareous sandy clay which may be equivalent to, or be, the Chattahoochee facies of Puri (1953b, p. 20) . If so, this is the first such recognition in this area. They describe a section of the formation Ii ear the Hillsborough River Dam as illustrating the interfingering of the clay and limestone beds. They state-"Most clayey beds in the Tampa limestone are small lenses, but several wells in Polk County, in cluding two drilled in 1952 at the Davison Chemical Corp. in western Polk County, were drilled through about 50 feet of rather uniform greenish-gray dolomitic sandy clay. This unit is tenta tively placed at the base of the Tampa; in the Davison wells it
PAGE 51
42 FLORIDA GEOLOGICAL SURVEY rests in sharp contact upon pure, white limestone containh1g Ca.ssidulus gouldii (Bouve). The wells in which the unit was noted roughly delimit an area with corners near Mulberry, Lakeland, Winter Haven, and Fort Meade." The Davison wells referred to here are wells 754-155-1 and -3 of this report. The Tampa Formation has been identified in relatively few wells in this county. Open-file logs of the Florida Geological Survey by E. W. Bishop and R. 0. Vernon identify the Tampa Formation from faunal evidence in a well south of Frostproof (742-131-2), and a well at Lake Wales (753-134-4). Examination of cuttings of the thick Miocene section in a well southwest of Lakeland (801-200-3), revealed no limestone in the Tampa For mation. Cuttings from wells 754-15-1 and -3 were studied and no evidence was found on which to base identification of Tampa limestone units in these wells as identified by Carr and Alverson ( 1959, p. 25, and fig. 7). Field evidence obtained during the. earlier phases of this in vestigation (Stewart, 1959, p. 22) did not justify an identifica tion of limestone in the Tampa in northwestern Polk County. A slightly sandy limestone, similar in lithology to early descrip tions of the Tampa was noted in northwestern Polk, and was tentatively placed in the Tampa. This has since been identified as Suwannee Limestone. The same report (Stewart, 1959, p. 23) also included in the Tampa Formation a "variegated (blue-gray or blue-green and cream) silty sandy clay'' which was thought to overlie the limestone unit of the Tampa. Figures 6 and 7 are geologic sections showing the formations penetrated by wells in the Polk County area. These sections were constructed from electric and sample logs. Data for the cased sections in wells were interpreted from drillers' logs. In order to identify the Tampa Formation in Polk County, it was necessary to examine logs in southwestern Hillsborough County where the Tampa Formation is better known and well defined. The corre lation of the Tampa Formation in the Polk County area is based on electric logs from Hillsborough County. In the Hillsborough County wells, the Tampa consists of a. limestone unit approximately 80-110 feet thick, and an overlying sequence of interbedded, bluish to greenish gray sandy clays with . stringers of sandy limestone and calcareous sandstone which may be weathered limestone remnants. The limestone unit overlies, and is in direct contact with, the Suwannee Limeston~. The clay unit of the Tampa underlies limestones of the Hawthorn Forma
PAGE 52
. :o~ ; JOO•.:.. : •oor' .. ,.,,,_ ! l 6{,,",J~ s I ! t ,o)L_ .. REPORT OF INVESTIGATION NO. 44 43 ij .. -.. .. . . ----Al t ,011uu.110" "•.... f('lfUU.ttO~ . .... .. .. .... -----l lliJl SIO~l >CO 0 . ., . --~ Figure 6. Geologic sections along lines A-A' and B-B'. Sections located on Figure 5. tion. The clay unit of the Tampa is cased-off in most wells. Some of these limestone beds have been almost completely replaced by gray, dense, very hard chert in wells west of• Plant City, Hills borough County (Menke and others; 1961, figs. 51, 54). The inter bedded limestones and clays of the upper unit of the Tampa in Hillsborough County appear to thin up-dip and merge with the limestone unit. These units, along with very similar units of the overlying Hawthorn Formation, appear to have been deposited in a shallow littoral marine environment suggestive of oscillatory stages. The Tampa is readily traced across Hillsborough County and into Polk County, and it is evident that the individual beds of this
PAGE 53
44 200 100 100 200 FLORIDA GEOLOGICAL SURVEY C c' . N N N ti, ! ,:. ! It) CD ' .n iii Nt~~~~M~WE=-~~~~;~!~~~~~-~-:-:=----i;:......-=~:-::-::--:r-~---7ai-:-, UNOIF CLAS TIC DEPOSITS -----RIVER FORMATION ,.,,,....---------INGLIS FORMATION -----.,.,,.,------PARK -LIME STONE 200 100 SEA LEVEL 100 200 300 300 400 400 0 I 2 J 4 5 m i lH I 1--sc::::I ----. . ----------------------------------------------D ;r: -c ... 100 ::, 4 0 200 ., ... Cl) a: '-' lOO ... > , , Cl) 400;__ ... ... ... ... ...; 0 .. _ ' .. -~ Figure ... '. Figure 5. N 0 CD o' .:i -; . a:, ,., ;. 0 0 (I) 0 0 GD GD ;:;;::~---l-~ASTJC OE POSITS f.QB.r.1~ ~RM4T1 -~ SUWANNEE LIMESTONE PARK o 1 "l 3 4 5 miln ~c=J FORMATION LIMESTONE 200 100 SEA LEVEL 100 200 300 400 500 600 700 --. ---------------------------' Geologic sections along lines C-C' and D-D'. Sections located on
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REPORT OF INVESTIGATION No. 44 45 ormation become thinner northward. This thinning is probably , lue to deposition rather than to removal by erosion. In eastern Iillsborough and western Polk County the Tampa changes up-dip, ,rom a predominantly limestone sequence to a predominantly ,lay sequence, and becomes the well-known "blue-clay" of local clrillers, the 50 feet of greenish-gray sandy clay of Carr and Alverson (1959, p. 2-5), and the variegated sandy clay of Stewart ( op. cit.). Possibly this clay is also related or identical to the ''residual mantle of green calcareous clay" of Cathcart and McGreevy (1959, p. 228), and to the "clay unit" of the Tampa Limestone as described by Ketner and McGreevy (1959, p. 64). The electric logs available do not indicate any significant change in character in the rocks above the blue clay of the Tampa, and it is believed that in Polk County these generally constitute only the Hawthorn Formation. To summarize, in Polk County the Tampa Formation is gen erally composed of a bluishto greenish-gray, calcareous, locally phosphoritic, sandy, shaley clay that contains lenses, fragments, and occasional thin beds of white to gray sandy limestone. The blue clay unit of the Tampa was found to be more extensive than stated by Carr and Alverson (1959, p. 25). This unit underlies the limestone members of the Hawthorn Formation in all but local areas along the northern edge of that formation, and east of the Lake Wales ridge. The Tampa Formation ranges in thickness from about 10 feet in well 805-155-2 to about 80 feet in well 752-150-1, although possibly even greater thicknesses exist. The blue clay in the Tampa Formation is important in the hydrology of the area because it is the lower confining bed of one artesian aquifer and the upper confining bed of another. The interpretations of the Tampa Formation in the present investigation tend to u.gree with those of Carr and Alverson ( 1959, p. 21), postulating the existence of Puri's ( 1953b, p. 19-21) Chattahoochee facies of the Tampa stage Qf the Miocene Series in peninsular Florida. HAWTHORN FORMATION In Polk County the Hawthorn Formation consists of massive, interbedded sandy limestones and sandy clays which are not individually distinctive. The clays are soft, sandy, phosphatic, and usually a gray to dark bluishor greenish-gray. The lime stone beds are light-cream to yellow or tan, very hard to soft,
PAGE 55
46 FLORIDA GEOLOGICAL SURVEY very sandy, clayey, and phosphatic. The beds are areally extensive but not really identifiable or distinguishable. Some of the beds appear to be nonfossiliferous but where the beds are fossiliferous, they contain casts and molds of large marine mollusca, silicified and phosphatized bones, and a few silicified shells. In mine pits east of Lakeland, the invertebrate fossils occurred in definite zones or beds that were traceable across the mine. Generally the basal limestone units have been dolomitized and are highly crystalline, hard, and resistant. This characteristic shows on the electric logs as a zone of very high resistivity and appears to be a more massive bed, as much as 20 feet thick. Along the northern edge of the formation the limestones are more highly weathered and earthy, and the dolomitic beds are less pronounced. Thickness of the formation differs greatly over the county, ranging from a few feet thick immediately north of the Lake Parker area to about 160 feet thick in well 747-158-3 at Bradley Junction. This is perhaps the greatest thickness in the county. The upper 2 to 10 feet of Hawthorn limestone were exposed occasionally in 1954-55 during mining operations in the Saddle Creek ~Iine just north of U.S. Highway 92 near Saddle Creek. A number of sections were measured, described, and photographed in these mines. Mining has since terminated in this location and all of the sections described have been mined-out, buried, or flooded. The upper surface of the limestone in these pits is us ually highly eroded and overlain by 1 to 6 feet of brown, sandy, gritty clay. Locally the limestone is overlain by brown, ,vell-indurated, clayey, sandstone which, in places, fills the irregu larities on the limestone surface. In a few small areas the limestone is overlain unconformably by lenses of white to dark-green, mas sive, dense, blocky clay. Both the clayey sandstone and the dense clay are included in the Hawthorn Formation. The limestones are sufficiently permeable to supply water for domestic and small irrigation requirements, and locally they con tain ,vell-developed solutional cavities which enable them to yield large quantities of water. The Hawthorn Formation overlies the Tampa Formation un conf ormably, and unconformably underlies sands and clays of l\Iiocene to Recent age. UNDIFFERENTIATED CLASTIC DEPOSITS Overlying the limestones of the county are sands, clays, clayey sands and sandy phosphatic clays. The age of these materials ranges from middle Miocene to Recent.
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REPORT OF INVESTIGATION No. 44 47 PHOSPHATE DEPOSITS Over much of the area ly_ing west of the northern unit of the '.Yinter Haven ridge and the southern part of the Lake Wales ridge, and generally south of the latitude of Polk City, the Hawthorn Formation is overlain by sandy clays containing pebble phosphate, which are in turn overlain by sandy clays and sands that have been largely leached of their original phosphate con tent. In part, these phosphate-bearing beds are a weathered re Riduum of the Hawthorn Formation, and in part constitute the Bone Valley Formation generally considered to be of Pliocene age. North of the latitude of Polk City and west of the Lake Wales ridge, outside of the general pebble-phosphate area, the limestones are overlain by sandy clays which have variously been described and placed in the Alachua, Tampa, and Hawthorn Formations by Vernon (1951), Cathcart and McGreevy (1959), and Ketner and McGreevy (1959), respectively. For the most part these sandy, slightly phosphatic clays are not readily identifiable in the field as to formation. In the area generally east of Polk City, Winter Haven, and Frostproof, and south of Polk City and Haines City, the lime stones are overlain by sandy, slightly phosphatic clays, and marls, or by clayey sands. In general, these materials are less dense than the phosphate-bearing clays in the western part of the county. These clays function as a confining bed for the artesian aquifers developed in the limestones of the county. In the remaining part of the county, north and east of Haines City, the limestones are overlain by generally less clayey and more permeable marls and sands. In the north end of the Lake Wales ridge and other parts of this area, the limestones are overlain by relatively clean or only slightly clayey sands. COARSE CLASTIC DEPOSITS Overlying the clays in some areas of the county is a deposit of clayey, poorlyto well-indurated, quartz sand which is gener ally white and very clayey in its lower portion and red to purple to orange and less clayey in its upper portion. These sands are micaceous and contain stringers and beds of discoid quartzite pebbles. Bishop ( 1956, p. 26) describes these sediments as grading downward into the Hawthorn Formation in Highlands County to the south of Polk and as a deltaic unit of that formation. Pirkle (1957, p. 21) describes them in Alachua County as a marine deposit of probably Pleistocene age. Ketner and McGreevy (1959, p. 71
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48 FLORIDA GEOLOGICAL SURVEY 73) discuss this unit, and assign it to the late middl~ Miocene or the early late Miocene. . The unit is very thick in the Lake Wales ridge. However, the unit appears to be absent from well 811-138-3 and others along this ridge. It is found in many lowland locations, though it is most prominent in the ridge areas. For example, remnants of the unit constitute the many low hills and knobs along Fla. Highway 33 in the area north of Polk City. The unit is used locally as a source for small domestic water supplies and is a part of the nonartesian aquifer. It is of consid erable importance to the hydrology of the county because of the high storage capacity available and resultant recharge to the underlying limestones. The entire county is blanketed by unconsolidated quartz sands, on which the present soils have developed. These deposits have been customarily assigned to the Pleistocene, as marine terrace deposits. Recently, however, Altschuler and Young (1960, p. 202203) have established that the surface sands in the Lakeland Ridge and the phosphate-mining area of west-central Polk County are ''mainly an insoluble residue of lateritic alteration of the Bone Valley formation, and not a transgressive Pleistocene deposit." The observed lack of marine terraces, shorelines, or related topo graphic features at supposed terrace elevations in this part of the county strongly supports these findings. Some terraces do exist in the eastern part of the county. These are best developed and preserved on the east flank of the Lake Wales ridge, south and east of the city of Lake Wales. STRUCTURE The rocks in Polk County dip at low angles and thicken to the southeast, south, and southwest, from the north-central part of the county around the southern end of the Ocala uplift. This broad dome, or regional anticline, is developed in the Tertiary formations of northern and central Florida, and it has been mapped and discussed in considerable detail by Vernon (1951, p. 47-58, and plate 2). The Ocala uplift is an elongate dome whose long axis trends northwest-southeast on an approximate line from Cross City, Dixie County, to Haines City in northeastern Polk County. Ac cording to Vernon (1951, p. 53) the structurally highest point on the crest of the _ uplift is in eastern Citrus and Levy counties.
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REPORT OF INVESTIGATION .No. 44 49 Vernon's structure map of the Inglis Member (now Formation) (1951, pl. 2) shows this high point to be outcrops of the Avon Park Limestone at altitudes of approximately 50 feet above sea level. Prior to the work of Vernon (1951, p. 47-52), fracturing and faulting of the rocks in Florida had not been recognized. He at tributes the development of these features to the compressive forces, and the relief of tensional stresses, associated with the formation of the Ocala uplift during the late Tertiary. Vernon states (op. cit., p. 50) "-The poorly consolidated sediments posing Tertiary rocks of Florida favor adjustments to strain by step fracturing rather than by bending. Because the tensional and shearing stresses would be greatest over the uparched area of the Ocala uplift fracturing developed by them would tend to occur in groups along the axis of the fold and to indicate the direction of greatest stress and of the elongation of the arch. If these joints are tensional they would tend to die out with depth because stretching is greatest toward the outside and least toward the inside. Available geologic data indicate that only tensional fractures are present in the area and that these are shallow." The present investigation shows that the crest of the Ocala uplift in north-central Polk County is within a few feet of being as structurally and physically high as the crest in Citrus and Levy counties. Figure 8 is a map of the geologic structure in Polk County, shown as contours on the top of the Inglis Formation. The contact of the Inglis Formation and the overlying Williston Formation is conformable and hence represents an un-eroded horizon which is suitable for structural studies. Structural re lationships are also shown by the geologic cross-sections -in figures 6 and 7. The configuration of the Inglis surface is the result of (1) the highly irregular surface of the underlying Avon Park Limestone, because the Inglis is relatively thin and did not fill in pre existing irregularities, (2) erosion of the .overlying rocks down to the surface of the Inglis, and (3) faulting due to uplift, after the Inglis was deposited. The northwest-southeast lineation, and the less prominent northeast-southwest lineation in the county align with the structural trends established by Vernon (1951, pl. 2). These features are the result of deep erosion of the Avon Park Limestone prior to deposition of the Inglis Formation. The parallelism of the hills and valleys strongly suggests that
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50 FLORIDA GEOLOGICAL SURVEY -.--......... ---Figurl' 8. Structure-contour map on top of the Inglis Formation. this erosion was controlled by fractures which parallel the axis of the Ocala uplift. The work of Vernon (1951, pl. 2) suggests that many of such fractures may be faults developed parallel to the crest of the uplift. These faults are the parallel, step-type f au Its. The vertical displacement along most faults is 60 feet or less. Irregularities in the structure contours in figure 8 suggests that numerous fractures and faults of small vertical displacement exist in the county, but the available geologic control is inade quate to define them. During this investigation faults were observed in limestone of the Hawthorn Formation at mine pit exposures in the Lake land area. Two of these faults, mentioned by Stewart (1959, p. 24), are located 0.15 miles north of U.S. Highway 92 and 0.45 miles west of Saddle Creek (fig. 2). The maximum vertical displacement of beds in one fault zone is 1 foot. Four separate fractures occur in this zone, which is the site of a solutional
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REPORT OF INVESTIGATION No. 44 51 ci ~ vern from which a spring is flowing. A second fault zone is located about 150 feet to the east and the vertical displacement along this fault is 6 feet. A spring also flows from a cavern developed in this fault, but the flow is at water level in the ditch and is less spectacular than in the first zone described. Normally water levels in the Hawthorn Formation are about 20 feet above the top of the limestone in the vicinity of the faults. However, water levels were temporarily lowered by continuous pumping from this excavation for mine water supplies, and to keep the active pi ts dry. Another fault was observed in this area, approximately 1,000 feet southwest of the faults described above. The fault (zone?) strikes N30W, with approximate dip of 80NE. The southwest side of this fault was downthrown approximately 6 feet. The fault appeared to be a reverse fault, both from the apparent dip of the fault plane into the upthrown block and the slight dragging of beds on opposite sides of the fault. The existence of the faults observed in mine workings could not be detected in the subsurface except by a long line of test holes spaced a few feet apart; and then only if the beds contained identifiable distinct lithic or faunal zones which could be used for correlation across the faults. The exposures in mine pits con clusively establish the existence of such faults and their relation ship to the occurrence of solutional caverns and the occurrence and movement of ground water. HISTORY OF STRUCTURAL MOVEMENTS Vernon (1951, p. 62) states that the movements which formed the Ocala uplift are post-Oligocene and pre-Miocene in age . He also indicates that some structural movements may have con tinued irregularly throughout later epochs. One of the criteria that Vernon used for dating the uplift was an apparent lack of : Miocene sediments over the structural high. However, Cathcart and McGreevy, Ketner and McGreevy, and Carr and Alverson (all 1959) each report the presence of Miocene sediments over the crest of the uplift. Carr and Alverson (1959, p. 66) indicate a late Oligocene time for the inception of the uplift, with renewed movement along a major fault on its crest in Polk County at the close of Tampa time. Several lines of evidence collected in the present investigation strongly suggest that the Ocala uplift started prior to the depo sition of the rocks of the Ocala Group:
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52 FLORIDA GEOLOGICAL SURVEY ( 1) Pronounced thickening of the Inglis and Williston Fo ,_ ._ mations in present structural lows. This strongly indicates that the faulting was recurrent through much of Eocene time. Some of the structural lows are probably downthrown fault blocks. (2) Pronounced thinning of the Inglis and Wil1iston Forma tions over present structural highs, and particularly over the cre~t of the uplift in the north-central part of the county. (:~) In a number of places all of the individual beds or units of the Crystal River Formation and the Suwannee Limestone thin markedly over structural highs and thicken in lows. This change in thickness is particularly true in the Hillsborough County and western Polk County and in northern Polk County. Such thinning and thickening is depositional rather than erosional. I Thus, it is believed that some areas which are presently struc1 tural highs associated with the Ocala uplift were also structural high,g during deposition of the Ocala Group and later rocks, and that movements which produced the Ocala uplift as presently kno\vn had their beginnings during the Eocene. The data also indicate that Home movement occurred as ]ate as Miocene time. SOLUTION FEATURES The lime.stones of Polk County contain many inter-connected openings, ranging from a fraction of an inch to many feet in size , which :1.re the result of solutional removal of the limestone by circulating ground waters. Small cavities have been observed in pieces of limestone that were recovered during well drilling from depths greater than 1,300 feet below land surface. Many large cavities. ranging from 1 to 40 feet or more in height, have been reported by IO<.'.al well drillers. Such openings greatly increase the water-transmitting ability of the rocks and hence the yield of u ell~. Knowledge of these solutional features, therefore, is con sidered essential to the understanding of the hydrology and geology of the limestone aquifers in the county, and in the re mainder of the state as well. Limestone (calcium carbonate) is slightly soluble in pur~ water. However, water which contains a small amount of acid will dissolve limestone much more readily. Rain reaching land surfac,? has absorbed carbon dioxide from the atmosphere, and the ga:; and water combine to form carbonic acid. During infiltration o:: the surface and percolation downward through the soils the wate1 ;
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REPORT OF INVESTIGATION No. 44 58 , ill absorb and combine with additional quantities of carbon ( ioxide from the soil. When the weak acid is in contact with l mestone for a long period of time, very large amounts of the 1 JCk will be dissolved. Many factors influence the amount and rate of solution, but two of the most important ones appear to be the amount of contact area and the length of time in which the water and limestone are in contact. The solution of limestone by circulating water is greatly facilitated by, and localized in, fractures, joints, and bedding planes in the rock because water moves n1ore freely through these relatively large, continuous openings than it does through the original or primary pore spaces of the rock. Solution and removal of limestone is, therefore, more effective and rapid along the fractures, joints, and bedding planes and is most effective at their intersections. An extreme development of solutional features nlong fractures occurs along fault zones in limestones of the Hawthorn Formation in the Saddle Creek Mine, east of Lakeland. rrhese faults have only 1 to 6 feet of vertical displacement. One cavern developed along the fault zones measured 8 feet deep, and another measured 3 feet deep. These are minimum depths, because ac curate measurements could not be made. Both caverns were 2 to 4 feet wide and were confined to the fault zone. The limestone elsewhere in the exposure is relatively devoid of smaller solutional tubes, cavities, and honeycomb as noted in the older limestones in table 4. Though fractures provide the avenue of easiest and greatest solutional excavation, and hence the largest caverns, the primary porosity in most of the limestones of this area is suffi ciently high to permit some passage of water in response to nat ural gravity flow. In inter-fracture areas, water moves much more slowly; hence, the quantity passing a given point per unit of time is less, and ::-olutional excavation is much slower. Small primary pore spaces Rlowly enlarge and coalesce and the limestone develops a fine textured, honeycomb or spongiform appearance. This type of solu tion is speeded by the removal of the shells and tests of marine invertebrates, particularly those of large mollusca and echinoids, leaving relatively large open pores. Honeycomb development was : tlso observed on many random pieces of rock recovered during drilling operations in other wells. With the continual movement of ground water and solution, extensive honeycomb and tubular networks develop simultaneously with major cavern development along fractures, where the rate
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TABLE .j, SoluUonal features penetrated by wells in Polk County (e, estimated) ."-Jthude of .\~,areQI L'SOS ros Allilude of bc>1&001 of i1hl Prob.Ible wtll l,d iD fNI featunt in of feature Geologic, oumher number aoo,e rnal fee& below uw in fl!el Tn• of fealure Ulli• Source of JAla Remark.a 739-12J-& W-668 82 73.1 13 J foa:wi)'COl!lb .\ ,on Park FOS 1eologic loa 741-139-3 H9 78:? 7 l'anrn do 01'"JJer .\ddhional 11nal1 cavitie.a re147 +71 do Hawthorn Driller ported abcm, tbi.l 7-140..1 6Jt 741 .. 1,n-1 132 273 Ii do Cl')'Btal Riv.tr Owuer 742-1 W.081 U>-l 7-16 3 Cuern fill Avon Park Driller's loc r 7-13-167-1 HO JOO 13 Cavern Hawthorn Owner 7-U-143,,1 180' +2 8 do do Driller 7-&a-H7 129 +IH IH do do Owner +108 3 do do do ! 745-148-3 W--4123 138 -76 2 do Tam~ Driller's loa 689 2 do .". ,on Park do 748-1~1 W-230& 163 703 7 do do do i 74S-IS8-8 137 60S 18 Porous aoae do Electric Jog Honeyromb! 7-15-169-2 160116 6 do Tam~ Driller "Loa of cuttinp" 746-143-1 Wsi-335 223• 687 10 Ca,eru .boo Park Driller'• Jog 0 746-HS-J W,i-3l6 1-19 691 3 do do do 1-18-150-J 153 677 3 do do Driller 747•U+l W-1728 01• 206 2 Porous 1oae Hawthorn Electric Joe Honeycomb? 747-133-2 W-978 128 500 33 do A,oo Park Driller's log ••IJ.me with cre,iees" 747-137-1 w-1110 147 812 39 do do do "Brown lime with crericee" 747-14.Z-2 160 635 ? Ca,ern do OW"Der Size not ch-en, depth to top of ca,eni 747-1'3-1 W-912 182 640 22 Poroua1one A,onPark log "Brown lime with CJ'evices" t:'/.l 643 3 Ca,ern do do d 747-144-2 w '-348 216 664 8 do do do "Break" ! 747-144-3 Wl!-343 206 6-19 6 do do do "Big water" 747-163-2 W'•lOOS 167 113 16 Ca,ero fill Suwannee do "Green Ibale and ..id" 639 24 Poroua1one A,onPark do "Loss of cuttings .. 6-16 7 do do do "Loss of cuttinp-water" 748-131-1 Wp-1012 243 1,060 31 Cavern fill Lake City? do "Brown lime and and" 748-144-2 w -342 212" 632 4 Ca,ern A,on Park do "Break" 748-146-1 ~139 210 612 2 do do do Occurs in interval 81&-822 ft 748-148-1 W-1050 110 'n7 3 Poro1111one Cr.,.,ital Rh-er Electric log Honeycomb? 748-148-4 W-995 110 618 2 Cavern A,on Park Driller's log 630 4 do do do 637 1 Honeycomb do do 748-148-5 W-639 115 643 4 Cavern do do 669 4 do do I do 680 10 do do do 749-144-J Wgi-364 232f' 634 68 Porous zone do do "BroWD lime rock cre,icea'' 749-146-1 Wli--471 217 160 20 Ca,-ern fill A,onPark Driller's Jog "Lime shells and sand" 749-146-2 Wei-378 231 10 35 Honeycomb Hawthorn do
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530 so do A,on Pork do 749-149-1 1.20 243 3 Porous zone Hawthorn Electric log 292 1 do do do 749-166-1 W;i-lOH 100 005 5 C1nern Ayon Pork Driller's lo,; 749-159-1 155 44 15 Hone)comb Ha,.-tborn Owner 750-142-3 Wgi-344 170 522 3 Ca, ern A'l"oD Park Driller's log Canty fill? 524 2 Gra,el do do 760-146-1 Wgi-485 100407 2 Ca,ern do do "Ca,e-in" 760-148-1 W-61 85 665 24 Cinern fill do do "Water, sand, hea,,. flow or water" 2,467 62 Honeycomb Oldsmar do 4,455 37 Poroua zone Lawson do '"Porous limestone with eand (Cretaceous) do lenses" (an;ty fill) 750-151-3 W-1395 136 641 2 Ca,ern A,on Park 760-168-1 151 4 5 do Hawthorn Owner 751-14~1 Wgi-337 135 689 08 Porous zone A,on Park Driller's log "Brown lime witli cavities" 693 4 Ca,ern do do "O 75)-14]-1 W-928 163 487 8 do do do i -146-1 W-974 176 606 7 do do do ' 751-1464 Wp-363 2128 615 22 Poroua zone do do "Cre,icee" 751-~46-3 Wgi-352 186 9 585 11 do do do "Cre,;ces" 0 751-146-2 W-1006 171 507 46 Honeycomb A,on Park Driller's log 751-148-1 W-2856 113 485 18 C1nern do do 751-166-2 W-2538 183 516 lH do do do J,-1 752-lSA Wli,-1019 201 233 15 C1uern fill Williaton do "Sand"; at top or Inglis? !z: 752-1'1-3 W~189 144 572 11 do A,on Park do "Cla:r with lilt" ;j 752-142-1 171 384 5 Ca,eru Williston Owner At top or Inglis! 752-142-7 W-1111 159 551 107 Honeycomb A'l"OD PArk Driller's log rn 665 112 Porous zone do do ''Bro'\\'U lime-cre,ices" 752-146-3 w -aas 176 615 71 do do do "Bro'\\'U lime ";th cre,;ces" is 752-146-4 w:l-a59 167 53 15 Honeycomb Su\\-nDDee do At top or formation? e; 752-146-3 Wa:i,-460 209 456 90 CA,ern fill A,on Park do "Water sand" 507 50 do do do "Shells and water sand" 6 752-146-4 W-1113 190 524 ? Porous zone do do "Hard brown lime, cre,ices in lo\\er HCtion" z 752-150-J 125 77 8 do Tampa Electric log At top or Sll'WIIDDee? 752-201-2 Wp-1020 120~ 520 68 do AYon Park Driller's log "Hard lime rock with smaU z C11\ern do do openings" $=> 591 1 734 4 do do do tr:. 752:-201-:3 Wgi-1021 120 565 35 Porous 1000 do do "Vicksburg lime, small openinp, no returns" tl=i620 5 C11\ern do do Wcll 25 ft easi of ""ell abo,c 753-138-1 Wgi-1023 183 177 ? CA,crn fill Crystnl Rher do "Sand com.i~ into well"; nt t::/l or Williston? 753-134-2 W-500 242 626 43 Porous zone A,on Pork do "F of ere,ices" 753-143-1 W-2151 151 617 12 Ca ,crn fill A,on Pork Driller's loc "Sand" 753-14&-5 Wgi.J67 162 583 32 do do do ""'ater, sand, and gm,el" 753-149-2 '"' 101 669 20 Porcms zone do do "No cuttinp returned" 753-149-3 W,i-371 1229 448 20 Honeycomb do do 753-150-3 W-945 116 342 18 Ca,ern fill Inglis do "Bro"n sand and soft lime rock": al top or formation? 329 ti do Williston do "Lime rock and ssnd" en t11
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T.ABLE 4. Solutional features penetrated by wells in Polk Count)' (Continued) Cl1 (e, estimated) CJ) AJaitud• of "1:!•rent US08 AJtilude uf hc.uow of i1bt Probable "eU 1.6d iD feel , feature iP c,f featurv (leulo1ic.number number at.)(l,tnutl feel below 1ual iP feel T)'llltl uf ft-alurv Coil :,,i,1m."t." uf da 141 llrmarl.11 713-160-.5 \\'-3304 12-1• 018 7 Porou, woe ,hon Park do "No t-uttin,p returned" 7M-UU-2 \\'-950 IUI .516 .. C'a,era do do 7JU-lH•I \\'fi-&3 122 ,\.56 33 Poro111 zosie do do "Bro•'fl lime -.ilh u1ien ere,•ic:ee" Te-1-160-2 Jl(lt' +23 2 C'a,e-ra Ta1111• llriller 76-1-162-2 \\'-1801 1-17 1128 7 lloae)'C'Olltb A,oo Park Driller's lo& At top of Lake City? lzJ 764-162--3 W-1802 1-10 009 8 do do do 76-l-166-1 W-110 136 039 Porous &One do do ••Cbanaed b)• aolutioa aetioo, s likely ea,emo111 11 7~16•M W-2098 200 ? 2 Ca,era :!:lu "1lDDN" do Euct depth nol reported, :! ea,-eru occunia theiotcrnl from 119 to IM ft 502 JG Cuem and A ,on Park du "\\'ater, aaad, an,,-.1, and -....... ,,. __ ea,em fill •mall ca,-ero'" i 7li6-130-l \Vp-1030 US" 23.5 .; Ca,em fill Iiwua do "Saad"; at top of A,on Park! 7li6-133-3 \Vp-1031 118 82 2 Ca,em t'r)-.tal Rher ,In ; 7M-166-1 \Vip-330 216 506 G do ,h-oa Park do 767-1 185 6-15 2:i do do do 761-133-2 WRi-3011 J.12 233 30 Ca,ern fill laalia do "Coral and "'lute saod"i at , top of A,-on Park? 122 332 85 do A,oa Park do "Coral and while •ad" 161al W-952 MO 2 Ca,•ern A,ou Park Driller's log 767-l W-1"'41 117 99 2 Porous zone Cr,-.tal Rher Electric log 276 1 do A,oa Park do UI 321 8 do do do i 4.57 2 do do do 767:-153-2 128 31 2 do SuwaDDee do 272 -10 Ca,era Cr,'81al Rh-er Driller Reported by a loc:al driller 7157-163-3 Wgi-3-10 1.22 473 8 do Avon Park Driller's Jos "C&vena. gravel-filled" 767-154-3 \V-22-1,J 167• M2 4 do do do 767-164-o Wgi-347 23-1 532 6 do do do ' a&-139-1 142 470 4 do do Tenant Present when drilled 7M-1.U-l Wgi-164 145 480 110 Ca,era till do Driller's loc "Lime and water sand" 758-1,52-3 1200 390 40+ Ca,ern do Driller Full dept , b not measured 758-163-1 W-1864 123 237 2 do laglia Driller's log "Sand' ' 465 2 do A,on Park do 758-163-l Wp-365 130 627 79 Porouszoue do do "Bro'l'l'll lime. rock with ere785-1';4.-1 ,ices" Wgi~I 128 12-1 7 Cavern Suwannee do At top of Cr,'Stal Rh-er? 22S 6 do ".,.ill.i.ston do .At top of lnglia? 422 8 do A,oaPark do 7.58-156-2 \V~-338 258 553 ll Porous zone do du "Ore,icea-big ,nater" 769-13-1-1 \Vgi-341 .2().l 491 ? Ca,em do do ApJJArent diameter not gi\•en
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,511 ? Ca,•ern and aa.nd do do 521 ? Ca,-ern-no sand do do 759-143-2 W-144,5 136 526 37 Porous zone Avon Po.rk Driller's log ''Three or four 1and ~iuoL ca,ities" 769-166-1 lV-2153 155 552 7 Ca,ern d, do Probably not bottom of well do d, -depth not given in log 759-159-1 W-2129 143 556 3}2 Porous zone "No cuttinp returned" 759-200-1 W-2954 136e +86 4 Ca,ern Hawthorn do +76 3 do do do +60 2 do Tampa d, At top of Suwannee? 759-201-1 W-632 132 255 2 do Inglis Electric log At top of Avon Park? 759-201-2 W-633 135 530 10 Porous zone Avon Park Driller's log "Cre,icee--hard rock" 535 5 Ca,ern do do 800-135-1 Wgi.-801 170 326 6 do do do "Sand in bottom of tbia stream" 800-153-3 W-724 119 341 2 do do do 611 15 Ca,ern fill do do ••Brown rock v.ith some sand" 800-166-2 139 58] 20 Porous zone do Driller "No cut= returned" .,, 800-156-3 132 138 20 do Ceyatal Ri,•er do "Lost circ tion" i 800-157-1" W-2015 204 516 50 Ca,ern fill Avon Park Driller's log "Sand" 568 12 Honeycomb? d~ do "Water" Ca,ern? Obsen-ation 800-159-1 W-3420 146 +13 11 Cavern fill Suwannee Dark organic clay, with small 801-138-2 W-4493 Hawthorn Driller's log clusters of satin-spar 128 52 4 Cavern 801-139-2 139 392 5 Cavern fill A,on Park Driller "Sand aod gra\'el" 801-139-3 Wgi.-1042 149e 281 10 Porou.a zone do Driller's log '"Lost cuttill&'II" t!3 801-146-1 150 8 20 ? Ca,•ern Suwannee Driller Top of eaTity-depth not re135' Avon Park Observation ported 801-200-3 Coro i2 310 5 Cavern At tocf of formation? 320 10 Cavern fill do Driller's log "San and mud" 412 7 Cavern do do 597 2 do do do 801~]-3 134 26 10 Porous zone Suwannee Driller "No cuttinp returned" 802-134-1 130 412 55 Cavern A,on Park Local driller z 802-1::18-2 193 417 3 do do Driller 5742 do du do z 802-136-3 Wgi~10-l3 "204 65 6 do Crystal River Driller's log 81 14 Cavern fill do do "Blue mud" ? 802-143-1 W-3305 147 436 7 Ca,ern Avon Park do 802-143-2 W-3306 144 +10 4 do Suwannee do "Break"; at top of formation? 11=1672 11 Porous aone Avon Park do "No cuttinp returned" 11=1802-143-3 W-3307 U.5 497 12 do do do "Series of caverna" 802-149-4 W-3633 130 433 8 do do do "Se,•ersl openis;,f wit-h water"; at top o formation? 820 5 Cavern and fill do do "Opeuipg of mud and odor of 802-150-3 Tampa Electric log gas"; st top of Lake Cit~? 119 ::0 5 Porou.a aone At top of Suwannee? 802-161-19 +21 ,5 5 do Suwannee do At top of formation? 802-152--10 W-3422 110 +45 8 do Hawthorn Obsen-ation., Loss of cuttings 802-154-2 142 ? ? Ca,ern ? OWDer Depth to feature and height . not gi,en,.,robably in bottom of we
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TABLil .a, Solutlonal features penetrated by wells in Polk County (Continued) en (e, estimated) 00 Alti&udJi of A,:reol Probable usos FOS Altitude of bouom of 1h1 well well lad In feet f•ture In of f•ture Oeololio Source of data number number above ma1 fee& below niaJ in feec Type of fea1ure Uni& Remarka 802-IM-l 1ss• +l-1 .. do Suwanoee Driller At Cop of formation? +10 2 do do do SO'J.167 2IO 40 6 Cavern SuwaDDee Owner Depth not ;ven, probably In Driller'• 101 bottom o well 802-167 \V-4163 191 471 2 clo Avon Park 802-168-1 \V .. 2767 193 623 3 do do do 630 4 do do do 803-l:W•l \V-468 IOI -159 60 Cav11rn fill do FOS Oe-ol. lo,r "Fine guarta and finely Tenant powdered llmeatone" =a 803-136-1 17-& -118 J2 Ca,er11 do Pre.eat when drilled i 803-)37-1 W-H16 UH 298 2 do do Driller'• lo1 .,S.Dd" 326 10 Porou, aone do do .. Lon eut~• and "Hooeycomb ch " i] 803-146-1 W-3-1-1-1 1415• ? ? Cavern ? do Depth and aiae not elvenprobably in bottom of well 803-145-2 W-2926 JM +13 2 do Hawthorn do ; ::cO 13 Porowi aone do do "No cuUi= re&uroed--aoO hoaeyco " 803-148-2 W-2720 163 -62 ? do Suwazuiee do "No auttia,a retumed" 803-147-4 W-872 169 ? ? Honeycomb ? do "No Jarae ca'ritla-oaly 4to a &-inch: opeD1111,11." Depth InAvon Park do tervall not reported. 803-1-17-12 Wa;i-1051 141 476 11 Cavern 803-153-12 124• +61 8 do Hawthorn do i 803-153-14 125• +21 3 do do Driller "0~ cavern and lou of cut. tiDD'' 803-163-2-a W-3426 124 67 16 Cavern fill Suwauee Oblservation S.nd-6Ued honeycomb ;J 808-153-28 W-3424 127 ::1:0 1 Cavern do Driller 803-164-31 138 12 1 do Suwanaee do ~ . 803-154-33 W-1800 1-11 429 10 Porot11 soue Avon Park Driller'• 101 "Leet cutti1111" 803-166:J-l Wd-80.'i 1-18 442 ? C11vern do do Sise not oven 803-158-1 W-2-l 218 402 22 Poroua •one Avon Park Driller's lo, "Oecuioiial creriee of cavern" 52-l 5 Cavern fill do FGS GeoL 01 "t:!• pebblee, C'• Poroua esone. blue c y, and PY j33e rite" 804-143-1 W-4412 19 2 Ca,ern Hawthorn Driller'• log ' I 806-136-1 175• 25 40 Cavern fill Cryatal River Owner "Saad, dry, under rock"; at .. top of formation? 806-136-4 202 +11 ? do do do "Sand ~ket"; at top of formation? . 806-~36-6 Wgi-105-1 100• 92 ? do dt> Driller's log ~•Toe of aand ~et-not drilled into' : at top of WUliaton?
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805-143-2 W-393 156 502 2 Ca\ern A\on Park do 806-147-3 1aa• 347 20 do do Driller 805-149-2 W-4188 159 426 2 Porowi aone do Driller's 101 "No cu= returned" l : :.. 805-163-4 W-4018 132 +48 19 do Suwamiee do '!Lein tiou" ; at top of •,>) . formation? I I Core #1 1309 382 do Avon Park Driller's log "Loet.all circulation": at top .. . . and obeemtion of formation. 399 do . do Driller's log Do Cavern fill do . do "Sand .sr:ket" 664 Poroua aone do do "Loet circulation" 664 9 Cavern fill do do "Sand cominc into hole" E 80$-156-2 W-3766 135 +43 2 Cavern Su'ft'llnnee Observation 80$-166-2 W-3769 136 +56 4 Cavern fill Tampa do At top of formation. 805-169-1 W-3312 206 54 43 Poroua zone Suwannee Driller's log •~Honeycomb" i ~ 806-187 W--3207 178 +34 10 Cavern Hawthorn do 360 1+ Porous zone Avon Park do "Water and aand" 8()6.187--3 W--3799 145 290 10 Cavern fill Avon Park Driller'• 101 "Soft 111nd" .,, 338 3 Cavern do do i 806-137.4 W--3802 143 82 5 Cavern fill Cr)"ltal River do "Sand" ! 184 2 Cavern Avon Park do 872 8 Poroua aone do do "Creviced broWD li01e" i I, 419 4 Cavern do do 806-187--5 Wgi-109 133 201 20 Poroua zone do do "Qutt_inp pau off into au~ surface nreama" fi-4 317 4 Cavern and fill do do ~•Cavi~ with coane brown ; sand' . 8()6.187-9 W-402 178 489 6 Cavern do do 512 10 Cavern fill do FGS GeoL loir "Sand" 8()6.138-1 W-464 129 484 33 do do do ''Sand with some limestone ' fragment&" s ~1ae.2 W--8771 136 +41 7 Honeycomb Suwannee Observation "a. to 8-inch cavitiee-88 to e; 95 feet" 807-1 181 119 15 Cavern Crystal River Driller .... ' 807-154-4 W--3883 135 417 2 do Avon Park Driller'• 101 o 807-1'67-2 WA884 154 426 76 Honeycomb do Driller 2: . 807-169-1 Wgi-1059 175' +6 1 Cavern Suwannee do sor-2 . 01-1 W-'J/174 143 85 2 do do Driller'• 101 Depth to cavity not pvenprobably at bottom of well ; ' 808-167-1 16'' +69 10+ Cavern and fill do Driller 10.ft cavern, then into clean . . sand 808-200-4 Wgi-1063 199 506 14 Poroull aone A,on Park Driller's 101 "No cuttings returned" ~186-3 166 +l 2 Ca,ern Crystal Rher Driller At tos, of formation? 5 6 Canrn fill do do "San " 8()9.147 W-4'1/15 135 376 18 Ca.,ern A,on Park Obs4!rvation (Dolomite pebbles up to 1inch diameter recovered from Soor of cavern) 377 1+ Porous zone do do "Honeycomb" 810-141-1 143 . 72 & CMern do Driller's 101 At top of formation? 810-147-1 161 324 1 do do do. 329 1 do do do 334 1 d:, do do en co , , ; ' l ,•,
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TABLE .j, Solutlonal features penetrated by wells fn Polk County (Continued) 8 (e, estimated) Altitude of Ar:;:01 U808 FOB AJtilude e;f bouom of J•robable well well t,d iD feel f•lunt iD of feature Oeoloeie D111Dber number abol• ma.I feel below mal iD feel Type cf feature Uni& Source of data Remarb SJ0-147-1 151 3H l do do do 3-l(f I do do do 372 3 do do do 810-J.55-1 W-3866 129 +19 2 Porou.t 1one SuW&DDee Electrie Joe &A 2 do c,,..w River do 8ll•l38-3 W-4.919 175 am 60 Cevera Avon Park 0W1IIU' r 315 1 Canra fill do do •S&ad'" SJJ.149-l 25 138 -1-17 5 Poroua lUlne do Driller'• Joe "No cuUiM9 retuned" 813-139-1 Wli-1068 163 347 Cavera fill do Driller ""&lad bed" -169 ? do do do Do e 6-19 ? do do do Do; at top of Lab City? 813-139-2 ]31 298 ? do do do Do 813-149-J W.JiCHG 132 20 ':fl do do Obeemation aand cant)' fill i 49 2 do do do 813-201 W-.53S2 Jo.; 95 5 Poroua zone Williatoo Obeervation No CuttiDD retumed lo.5 JO Honeycomb la,lia do Few euttiJIP retarned 130 J Canru Avon Parle: do 8 140 J do do do 81.C-138-1 18-1 lJ6 IO do do Driller 814-139-1 18-1 361 91 Ca..-eru fill do Driller"• Joe Limestone aod IIIDd beda B 815-139-1 Wgi-1009 189 39-l 123 Poroua sone do do cutti.Dp retarned .. 815-167-1 W-3840 109 +65 1 Caveru Cr.vatal Rive-r Obienation 815-167-2 W-3839 109 11 6 Poroua 1011e Williston do "No euttincs reeovend" 14ff 3}2 Canrn do do DJ, 20 SJ Pcrouasoae I.DI.lit do Do i ' 21 J, Cavem do do 31 5 Boc,comb do do Small eariti• ~' 36 5 do do With quarb eaad 41 1 Canm do do MS 46 s+ Cavens fill do do Saad ea~-&D prennta furI ther DC 816-146-1 W-4689 128 17 1 Cavern do Driller Sile -' reported; al top of formation? 261 1 do Avon Park Obeerntion 26-l 3 Honeycomb do do No cuttinp recoTered 276 12+ Ca,eru fill do do Quarts aild-prenDta .drill 817-139-2 209 9-l 3 Cavern Avon Park Driller's log OIi 28'l 13 Cavern fill do do "Sand" 817-160-1 ~-1073 159 216 IO Cavern do do 818-140-1 gi-1074 218 602 5 do do Driller . "Saad" ' \' 602 1+ Cavern fill do do ':'' ,:':? 818-164-2 114 +M 2+ Cavern Cr,-stai River OW"Det At top of WillistOII? , , ,. l_ i~1 '" ''i"I
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818-155-2 Wgi-1001 1os• 10 13 Filled ca,..ems Inpls Driller uun1~.a:n:.e .J.:; ! : .. . ; . :~'.. ; . . tc,p of formation? . ' ~ ' .. 18 r, Cavern do do "Sand alld muck" ;' _: ~ 19 1 Cavern fill do do i ' ' ~ . , , i .... \-:' s ~ a , , " ' ' , ' s ' ' ' z . ' . z . IP-, IP-, '' ' /
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62 FLoRIDA GEOLOGICAL SURVEY of development is much faster. Tributary flow thus becomes es tablished in an elementary pattern, controlled by fractures, and the cavern system is enlarged and extended with time, much as surface drainage systems are developed. This process progressively increases the water-transmitting ability of the limestones. As the solutional caverns become larger the roofs, in some instances, may slowly become incapable of supporting the over lying materials and eventually collapse. If the collapse exte?1ds upward to land surface, a sinkhole is formed. Obviously cavern systems functioning as ground-water con duits or drainage systems must have a terminus, or point of discharge. In artesian aquifers, such as those in thisarea (Stewart, 1959), the cavern systems will not discharge at land surface unless land surface is below the piezometric (pressurehead) surf ace of the aquifer concerned. In such discharge areas, concentrated flow at Japd surface, as artesian springs, will occur where the confining beds are breached. It is likely that most of the discharge of cavern systems of Polk County occurs through the multitude of artesian springs in Hillsborough and other ad jacent counties to the south and sou~hwest. The only significant artesian spring in Polk County is Ki~engen Spring, southeast of Bartow. The so-called "Ft. Meade Spring," just east of the town of Ft. Meade, is actually a man-made pool fed by a flowing artesian well. Diffuse discharge at a low rate probably occurs as general upward leakage through confining beds in areas where the arte sian head is great, and confining beds are not visibly breached. In Polle County such an area probably exists over much of the valley floor of the Kissimmee River below Lake Kissimmee, and of the Saddle Creek-Peace River system below U.S. Highway 92, east of Lakeland. CAVITIES During this investigation data was compiled on open cavities, honeycomb zones, and zones in which ~irill cuttings were lost at depth in the limestones of the county. Beds of unconsolidated quartz sand and similar sands encountered in the bottoms of open caverns are all interpreted as cavity fillings, because such deposits are not known as regular primary sedimentary dep0sits in the rocks of Tertiary age in central Florida. Such deposits, along with the other solutional features, are tabulated and pre sented in table 4. The locations of these wells and the altitude of the base of the deepest feature encountered are shown in figure ,9.
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.... ,_ ....... us '-""'itt •' ..... .. . . __..,. .. ..... , REPORT OF INVESTIGATION No. 44 0 I J' J ,. , .. , ~,-.=, 63 ., . I ,,,, I Figure 9. Map showing the location of wells penetrating solution features in the limestones. The preponderance of solutional features in the harder, more crystalline, Avon Park Limestone is evident, and these total 65 percent of all solutional features recorded. Many of the weUs shown in table 4 do not penetrate the Wiiliston and Inglis Forma tions and the Avon Park. Thus the number of s~lutional fea tures in the Avon Park may actually exceed the proportion indi cated. The table includes data from 190 wells and it records 27 4 separate features. It is believed that if detailed drilling logs were available from all wells in the county, the actual number of wells which penetrate solutional features would be vastly more than the wells now tabulated. However, such logs are available for less than 400 of the more than 1;300 wells inventoried during this investigation (Stewart, 1963; table l). A number of general observations may be made from figure 9: I. Multiple zonesof cavern development, at different altitudes, exist in the same local area, as -in the area west of Lake Hancock.
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64 FLORIDA GEOLOGICAL SURVEY 2. Locally the data show a definite correlation of altitude of cavern zones, as in the area immediately west of Lake Buffum at -650 msl, and in the area southwest of Lake Parker at -550 msl. These zones may be part of an integrated cavern system. 3. Four wells (750-148-1, 754-152-2, 747-137-1, and 741-139-2) penetrated cavern systems or solutional features at depths in e.~cess of -900 msl; one of these (750-148-1) penetrated a honey comb zone at -4,455 msl. 4. Numerous solutional features exist at altitudes above msl, particularly in northeastern Polk County. 5. Caverns have developed in areas where the limestone is deeply buried, as in the southwestern part of the county. 6. In general, the caverns of the Lake Wales ridge are at shallower depths below sea level than those of other parts of the county in the same latitude. A comparison of figures 4, 5, and 9 suggests that the general distribution of wells known to penetrate solutional features is more closely related to the distribution of well data, than to the geology of the area. Data are very sparse for southeastern Polk, because few wells have been drilled in this area. As this is an area of general artesian flow and upward leakage, it may be assumed that large caverns such as those known and reported in Hillsborough County may exist in greater numbers than the map indicates. In general, there appears to be an increase in depth below both land surface and msl of the deepest local cavern zones with increasing distance from the north-central part of the county, following the slope of the piezometric surface and formational dip. The study of the cores from wells 805-154-8 and 801-200-3 produced detailed data on the solution features of the underlying limestones. The cores show a concentration of solutional fea tures in the Avon Park Limestone. A series of cavern develop ments and subsequent collapse and filling in the Avon Park Lime stone, and a few features in the underlying Lake City Limestone, . occurred prior to dolomitization of these formations. These caverns . show, in many cases, a second stage of solutional excavation and fill which occurred after dolomitization. In several instances these solutional f ea tu res strongly suggest a third stage of solu tional excavation, now occurring in the second stage fill. Ab stracted logs of these . two test holes and of well 815:-157-2 pre sented earlier indicate the extent of solutional features observed ..
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REPORT OF INVESTIGATION No. 44 65 In addition to this series of features, three separate caverns were penetrated in the Avon Park Limestone in well 801-200-3; these were in the intervals of 440-445 feet, 5401/2-547, and 729-731 feet, respectively. The upper cavern ( 440-445 feet) was underlain by quartz sand and mud fill from 445-455 feet. The middle cavern was apparently underlain by 10-5 feet of soft mud and sand fill, and/ or very soft honeycomb limestone, because casing was set through this interval without drilling. Limestone-filled solutional cavities were also found in the upper surface of the Suwannee Lin1estone in well 801-200~3. After development of the solutional features, the surface of the Suwan nee was replaced by chert. Limestone of Miocene age [Tampa ( ?) Formation] which contained numerous Sorites sp. was then de posited and filled the preserved solutional features. No significant solutional features, other than some fine honey comb, were observed in the soft, chalky, highly calcareous Suwan nee Limestone or Crystal River Formation in wells 801-200-3 and 805-154-8. SINKHOLES Undoubtedly the most spectacular surficial evidence of solu tional activity is the formation of collapse sinkholes. Thirty active sinks were recorded in west-central Florida from 1953 to 1960. Nineteen of these have occurred in Polk County, including those referred to by Stewart (1959, p. 13-16), and all of these are listed in table 5. Location of these sinkholes are shown in figure 10. Because of the relatively small diameter and observable depth, all of these sinks are believed to have ,had their origin in the upper-most limestone of the area concerned. Study of the data in table 5 and the piezometric, structural, and geologic maps pre sented elsewhere in this report indicate a wide variety of local conditions at the different sites. None of the sinks occurred on local topographic highs. Land surface at the sites did not exceed 150 feet above sea level. Land surface at 13 sites is 70 feet or less above limestone; at 5 sites the depth to limestone ranged from 100 to 225 feet. Only six sites were not closely associated with, or adjacent to, pre-existing sinkhole areas. Figure 11 shows two of the sinkholes developed recently in the county. Between -1953 and 1960, 11 sinks were formed in adjacent Hillsborough, Pasco, and -Hernando counties, and probably others occurred elsewhere. Though most of these sinks have been of
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66 FLORIDA GEOLOGICAL SURVEY . I l __ \ \ \ \ Ciry \ EXPLANATION o'o Sinkhole Location number refers to number in Tobie 5. \_ ) 5 IOmiles ======== Figure 10. Map showing location of recent sinkhole collapses. small dimensions, their sudden appearance has caused consider able local alarm. The formation of sinkholes is a completely natural occurrence and perhaps most vividly illustrates the principal geomorphic process operating in this area. Other such collapses in the future are a certainty. The multitude of round, closed-in basin lakes in central Flor ida and Polk County are widely held to be of sinkhole origin, and as such are evidence of considerable solutional activity inthe geologic past. Though many of them may have occurred prior to the historic past, they are none the less spectacular due to their size and numbers. The smaller lakes in Lakeland, such as Lakes Mirror, Wire, and Morton, are almost certainly single sinks. Be cause of their very circular shoreline, larger lakes, such as Hollingsworth in Lakeland, Ariana in Auburndale, and Howard in the City of Winter Haven, and scores of others in the county, are also believed to be single sinks. A number of large lakes, with
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TABLE 6. Records of the occurrence of recent sinkholes . Polk County m ( Reported data shown by "r") I Location Diameter Depth in Altitude in i Number Date of Mode of in feet at feet below feet above Quarter Township Range Nearest (on fi~'. 13) collapse occurrence land surface land surface land surface section Section south east town 1 1953-54 (4) Instant 8-12 12-40 r 115:1: SE 6 30 25 In Bartow 4-54 NE 7 t-1 2 do Sr Sr 130 NW 15 28 24 Lakeland i 3 9-54 do 22 4+ 110:1: NW 11 28 24 Lakeland 4 5-8-55 do 30 30 135 SW 14 29 24 Highland City 5 4-7-56 do (40 r) NE 30 West Lake Wale" 83 20+ 120 7 'J/1 (40 r) 6 4-56 do 40 r 4r 175 :1: NW 34 30 26 Alturas 7 4-9-56 (2) 3 months 30 1-lij 126 NW 23. 29 25 Bartow 2 houl'S 100 10~ 8 4-10-56 Instant 75 r 130.1:: SE 34 28 26 Winter Haven B 9 7-57 do tiO 16+ 150 NW 22 29 24 Lakeland 2l 10 9-10-57 do Sr 10 r 115 NE 7 30 25 Io Bartow 11 11-8-58 do 60 r 40 r 100:1: SW 6 30 25 Bartow 12 4-17-59 do 5 9-10 140 SW 30 27 24 Lakeland 13 5-5-59 do 70 r 40 r 130 NE 33 28 26 Winter Haven . 14 5-28-60 do 30 unknown 140 SW 17 27 23 Kathleen t
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68 ~ .A ... . ~ . tr = FLORIDA GEOLOGICAL SURVEY Figure 11. Photographs of recent sinkhole collapses.
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REPORT OF INVESTIGATION No. 44 69 ~ rregular or complex arcuate shorelines, such as Bonny, in Lake land; Gibson, near Lakeland; Crooked Lake, at Babson Park; a nd many others, are a coalescent group of smaller sinks, or are more properly referred to as valley sinks. For example, Lake Bonny in Lakeland, at a stage about 6 feet below normal in June 1956 was shown to be formed by a group of smaller adjacent or coalescent sinks by aquatic grass and other vegetation growing around the periphery of the small sinks in the shallow water. Many sinkhole basins contain only ephemeral lakes or ponds. Such basins range from several hundred feet in diameter and scores of feet deep to a few feet in diameter and depth. The larger, deeper sinks are profuse in the Lake Wales ridge section where the relatively porous overburden is very thick. The original depth of the sinks (or depth to point of collapse or cavern) is generally unknown. Wells on, or near, the floors of sinkhole basins are few because well drillers have found that unconsolidated materials in such basins may extend to great depths. This requires great amounts of well casing, and fre quently presents considerable difficulty in drilling, installing the casing, and developing the well. To further complicate drilling in such locations, the honeycombed, fractured, or cavernous lime stone, is commonly impregnated by sands, silts and muds which reduce the yield of the wells, and require additional casing in most instances. HYDROLOGY Hydrology is the science that relates to water on and within the earth and in the earth's atmosphere. ,vater moves continually from one to another of these environments, and man diverts a part of it, temporarily, for his use before releasing it back into the cycle. A relatively small part of the rainfall runs off over the land surface because of the permeable sand cover . A larger part of the rainfall is returned to the atmosphere by evaporation fron1 the soil, bodies of surface water, and the vegetation. Part of the rain fall infiltrates the surface and percolates downward into the soil, and much of it is held as a film on soil particles, taken up by plants, and subsequently transpired back into the atmosphere. The water in excess of these requirements percolates downward through the soil and remainder of the zone of aeration, and eventually reaches the zone of saturation to become ground water.
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70 FLORIDA GEOLOGICAL SURVEY Within the zone of saturation, water moves through the earth materials, in response to gravity, to points of discharge such as springs, lakes, streams, oceans, and wells. The appraisal of the ground-water resources of the county is at best only an approximation, because none of the quantities involved in the various factors can be measured directly runoff and precipitation. Techniques for accurate measurement of evapo ration and transpiration do not exist as yet, and even adequately detailed measurement of rainfall and runoff are seldom possible and always costly. Because of variations in climate, and the requirements of man, it follows that the quantity of water available in an area will differ from year to year. SURFACE WATER STREAMS In general, surface drainage in the county is poorly developed and is almost entirely of two types: (1) basins of interior drainage (without surface outlet), and (2) streams of very low gradient which, for the most part, do not occupy well-defined valleys. In many places these streams have not cut well-defined channels. The county lie~ within six major drainage basins, as ordinarily defined, and these are shown in figure 2. Approximately 15 percent of the county is drained by the Withlacoochee River which forms part of the northern boundary of the county (Heath, 1961, p. 8 and fig. 8). The river flows west into Pasco County, where it turns sharply north and empties into the Gulf of Mexico near Inglis in Levy County. About 4 percent of the west-central part of the county west of the Lakeland ridge is in the headwaters of the Hillsborough River and about 8 percent of the southwestern part of the county (Heath, op. cit.) is in the headwaters of the Alafia River. The area between the Lakeland and Lake Wales ridges, and south of Providence, Auburndale, Lake Alfred, and Haines City, is in the basin of the Peace River. Approximately 35 percent of Polk County lies in this river basin (Heath, op. cit.). A narrow finger of the headwaters area of the Oklawaha St. Johns River basin extends into northeastern Polle County, along the west flank of the Lake Wales ridge, north of .Haines City. This area (2-3 miles wide) represents 3 percent of Pollr County (Heath, 1961, p. 10), and is drained by Green Swamp Run~
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REPORT OF:' INVESTIGATION No. 44 71 The east~rn 35 percent pf the county . (Heath, op. cit.) is in the basin of the Kissimmee RJver. . Tributaries of all of these rivers are gener:;tlly short, poorly defined, and few in_ number. The course of the Withlacoochee in this county is a thickly timbered cypress river-swamp that ranges from about a hundred feet to more than a mile in width. Where the channel of the river can be defined within the swamp, it is generally less than a hundred feet wide. The Peace River has a well-defined channel between Bartow and Ft. Meade. Table 6 shows the annual runoff in three drainage basins TABLE 6. Annual runoff by drainage basins, in inches of water over the basin (Data supplied by Surface Water Branch, U.S. Geological Survey, Ocala, Florida) Station 1954 1955 1956 1957 1958 1959 Alafia. River at Lithia., Hillsborough County 14.28 8.40 5.37 18.56 13.26 34.42 Area: 335 sq. mi. Peace Rher at Bartow, Polle County 8.00 3.89 4.47 14.40 10.49 28.16 Area: 390 sq. mi. Peace River at Zolfo Springs, Hardee County 12.21 5.63 5.42 14.63 12.10 27.52 Area.; 840 sq. mi. Kissimmee River below Lake Kissimmee, Polk County Area.: 1,609 sq. mi. 10.93 4.28 2.60 9.30 9.27 20.38 during thjs investigation. Runoff is give11: in inches of water over the basin area. The stations listed here are those nearest to, or within, the . county . in the drainage basins. Runoff from the Withlacoochee and Hillsborough basins cannot be evaluated be cause of diversions through the Withlacoochee-Hillsborough over flow. The Withlacoochee and Hillsborough basins therefore are not included in Table 6 or in the sections on recharge. Numerous other stations . exist on . tributary streams and canals within the county. The records of these basins, only a few years of_ which are given here, show great differences in runoff frQm each. drain age basin from year to year, and between basins during the sam~ year. . The ridges are drainage divides, however, actual surface runoff from them is almost nil due to . the thickne_ss and permeability ot the su:rficial s_ands, and to the numerous closed basins . of interior drainage located on the ridges. For this reason large areas within a drainage basin actualJy . contribute ve_ry little direct surface . run
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72 FLORIDA GEOLOGICAL SURVEY off to streams. Rainfall in these areas infiltrates to the water table and percolates through the nonartesian aquifer in response to downward loss, lateral flow, and storage. A part of this water is eventually discharged into surface-water bodies, but only a few such bodies are a part of stream courses. LAKES Heath (1961, p. 8) states "Nearly 500 lakes, ranging in size from less than an acre to more than 35,000 acres (55 square miles), lie within the county and along its borders." Nine of the largest lakes are within the broad eastern lowland. They are con nected to the drainage systems by means of natural or artificial channels. It is unlikely that these lakes lose water downward through the bottoms because they are within areas of significant artesian flow. Most of the other large lakes in the county are likewise connected to drainage systems. A majority of the lakes in the county, however, are closed basins of interior drainage at the present time. The entire length of the Lake Wales ridge in this county is pocked with and flanked by innumerable closed basin lakes. There are also many sinkhole basins without lakes, and like most of the lake basins they have no surface outlet. The porosity and perme, ability of the thick surficial sands of the ridge do not permit surface runoff, and the thickness and permeability of the mate rials filling the bottom of these sinks likewise do not permit pond ing of water. The bottoms of these dry sinks are 20 to 50 feet or more above the water levels in the underlying artesian aquifers, while water levels of the lake-filled basins are generally 2 to 10 feet above these ground-water levels. It seems likely that in much of this area, ground water percolating down the slopes of these dry basins is going intothe artesian limestone aquifers as re charge. These dry sinks range from 100 to 1,000 feet in diameter at the top of their funnel-shaped basins, but most are 200 to 500 feet in diameter. Topographic depth of the sinks ranges from 25 to 75 feet, the smaller and more shallow basins being found on lower parts of the ridge flanks or within larger and deeper basins. In the Winter Haven and Lakeland ridges, and in the central and northern inter-ridge areas, dry sinks and basins are few in number~ though lake basins of interior drainage are numerous. In these areas the surficial sands are not as thick as in the Lake
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REPORT OF INVESTIGATION No. 44 73 Wales ridge. In these two areas the surficial sands are underlain by greater thicknesses of less permeable materials, and, being lower topographically, the water table is closer to land surface. The water levels of the artesian systems are also closer to land surface except in the highest parts of these ridges. These factors all operate to increase the percentage of lake-filled basins in these areas. The lakes of the county are of significant value to the hy drology and economy. They serve to moderate temperatures and climate, they function as reservoirs for water which might other wise leave the area more rapidly as streamflow, and they provide large supplies of water for irrigation and recreational purposes. Lakes supply numerous lawn irrigation systems in the cities and towns along the Lake Wales and Winter Haven ridges. In Lakeland and the Lakeland ridge section generally, the use of lakes for lawn and citrus irrigation is relatively much less than in the other areas. The City of Lakeland pumps water from Lake Parker and Lake Mirror for cooling purposes in a~jacent power plants. Lakes Gibson, Crystal, and Bonny have been used for citrus irrigation in the past, but such usage has been discontinued in recent years largely because of legal proceedings and injunctions. Scott Lake, south of Lakeland, is still used extensively for citrus irrigation whenever irrigation is necessary in the surrounding groves. Lakes and ponds fluctuate in response to rainfall, ground water inflow, evaporation, downward loss to underlying aquifers by percolation through the lake bottom, to surface inflow and outflow, and to pumping. The quantities of water involved in these transfers are dependent on topographic, climatic, and geologic factors, and the hydrologic setting of the individual lake basin. The net effect of these factors differs widely from one basin to another, as shown by the hydrographs in figure 12. Relative im portance of the controlling factors is not always evident. As a result, the prediction of the effect of individual factors on a given lake is not valid without evaluation of the other factors involved. Detailed discussion of the basins of Lake Parker and Scott Lake in the Lakeland area, and the response of these two lakes to the factors above, are presented in the section of this report entitled Special Problems. Lakes Wire and Hollingsworth are in the City of Lakeland and on the Lakeland ridge. Lakes Deeson, Crystal, and Bonny are on the lower ground along the east flank of the ridge. Hydrographs
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194 L...:..:...:..:..:..;~u.. ...... .:..:...:..:....;:..;...u..;...:..i.....:..:.v.i..:....i.J..L.u.J..Ju..w..J..:..u..:..:..J...w...u...:..:...:..:..wu..w..1..1..! 1 ..L.! 1 ..J... 1 :..'w.. 1 .u 134 ..... --------------__,..,..,....,.....,..,..,..,..,..,_,.._,......,..,.....,.....,.....,..,..,._,..,..,..,..,,..,..,..,. ..... ..,..,..,..,..,...,, ... ., 1.l& z I~ .. "'133 > 0 .. :31 , , , , J -----,---, , .. _.l!lC ,ze ----------t -----' ,z-r i----..;..;..;...;.~.;_.;._~...:..:..:...~ .......... -'-'-'----'---'--------'---'-'--'-'---'--'-...... 1 ...... -'--'-'--'............... > 134 -------i-.-.-.-----i-,-,-,,---.-.-,-.""1---,-.-------""""1-------,-------,-, -,--l.l(J 1211 i -i---,-------t--! i l -p --------+ -----;__ ___ ---'I' I .. ''.' I I'' I'''''' I l;:4 '--------------'------~------~------------~ 14 ....-------------""""--"'"'..,..,,...,..,..,...,..,.-_.,.,"T,,..,,.,,,-,,-,--,-,--,--,--,---,--,-.,.-,-,--,-,,-,--1 :-, -:-, .,., .,._ -,-.,.-,--,-, ~-------1-n-------: 12 LA~ELAND ., ~:O 0 1----------~---+-t----''~-----H--j_-11-'1---+7'+--,-------,c---i-t't--'M ~-----___j-+l+l'1+-!-!7-i :: 6 -----~----,--v i'/ .. ; 4 1---....+--H;--t,.,r--+---1H:-t;,t--+---t--H7'H:,f"t~-t~:-t-1c,t;,-!ovt,t,'1I' / : 2 l---f..H-!:-f.!f+,1"1"1R--iE'l""<-A~4_ "-1_ ?l_vv"'~+'l,...-_-1'. r::-f: -1. :t_Jy_lvl/;+ -jt:,v vblval m"H, H,, 71,9_ ~+_ -l_ 'ii}~.'_ "I:~ Ll,_'i]-1,-1'. v-1'. A":.+1H: ;t',f:,H~, : '. v ! ITT . -~ v ihtlttt A fl; 11 7-1'. O JFMAMJJASONOJFMAMJJASONOJFMAMJJASONOJFMAMJJASONOJFMAMJJASON JFMAMJJASON 1'15-l I1957 1958 1959 Figure 12. Hydrographs of water levels in Lakes Wire, Hollingsworth~ Deeson, Crystal, and Bonny near Lakeland and rainfall at Lakeland, 1954..;59_ 74
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REPORT OF INVESTIGATION No. 44 75 for nearby Lakes Parker and Scott are presented in later sections of this report. Additional data on lake levels, collected as a part of this . investigation, may be found in the basic data report (Stewart, 1963). Lakes Hunter, Beulah, Morton, Mirror and Gibson, all in the ridge section near Lakeland, fluctuate closely in time and amount with Lakes Wire and Hollingsworth. Water levels in Lakes Deeson, Crystal, and Bonny, near Lake Parker, declined about 6 feet, and Lake Wire declined 1 foot between December 1954 and July 1956, whereas the water levels in Lakes Parker . and Hollingsworth and other nearby lakes re mained about the same. Hydrographs of the six lakes for 1954 correlate reasonably well. Lakes Bonny, Crystal, and Deeson have no surface inflow or outflow. Topographic gradients within the basins are generally low, and the slope of the water table is assumed to be low also. The average flow of ground water into the lakes is probably equivalent to only a _ few inches per year over the lake surface, and this amount was undoubtedly below average during the dry period from January 1, 1955 through June 30, 1956. Ground-water out flow in the nonartesian aquifer is believed to be zero. One phosphate test hole near the west shore of Crystal Lake showed predominantly sandy materials extending from the sur face down to the limestone bedrock. A good hydraulic connection such as this may also exist in parts of Lakes D~eson, Crystal, and Bonny, permitting relatively rapid downward leakage. During the same dry period (January 1955 to June 1956), pumping from the artesian aquifers increased as recharge de creased, lowering artesian water levels 5 to 10 feet. This in creased the hydraulic gradient between the lake levels and the artesian aquifers and probably increased the rate of leakage from the lakes. The combination . of decreases in rainfall and ground-water inflow plus increase in evaporation and vertical leakage appear to have been sufficient to account. for the d~cline in lake levels. With the return of nearor above-normal rainfall late in 1956, lake levels began to -rise. In November and December 1956, the outlet of Lake Parker was raised 1 foot by the City Engineer of Lakeland. The surplus . water created was then pumped into Lake Bonny~ The pumped water, . plus the rainfall; accounts for the sharp rise in the level of Lake Bonny in November 1956, which amounted to approximat~ly 2 feet Continued above-normal rainfall in most_ of . 19 . 57 -returned the lakes to, or above, .their
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76 FLORIDA GEOLOGICAL SURVEY 1954 levels. Lake Deeson was the only exception to this in the Lakeland area. The cause of this lack of recovery by Lake Deeson is uncertain and data are few. A major factor may be very localized below normal rainfall. Similar instances are indicated on the hydro graphs of Lake Bonny in September-October 1955, and at other times. This is possible because of the predominantly thunder storm-type of rainfall in the entire area. Lake Deeson's failure to recover in 1957 and in 1959, as well, may also be due in part to increased local pumpage and downward leakage from t~e basin. The lakes all declined in 1958 because of below-normal rainfall. In 1959, record high rainfall was established at the Weather Bureau office at Lakeland when a total of 70.24 inches was re corded. All the lakes, except Parker and Deeson, exceeded their 1954 levels by significant amounts. In September 1959, it was necessary for the city and county to reverse the procedure of 1956, and excess water from Lake Bonny which threatened shore line property was drained into Lake Parker. Stage measurements of Lake Ariana in Auburndale, and Lake Hancock near Highland City, in 1958 and 1959 (Stewart, 1963, p. 106) show that these lakes also fluctuate closely with those in the Lakeland area. The range of fluctuations of these lakes ap1 pears to be about equal to those of Lake Wire for the 2-year period. EVAPOTRANSPIRATION The term "evapotranspiration" has been used to denote the return of water from the earth to the atmosphere by direct evaporation and by the life processes of plants. It includes evapo ration from water surfaces as well as soils and vegetation, and the transpiration by vegetation. The source of data on evaporation from free-water surfaces nearest the area described in this report is a standard U.S. Weather Bureau evaporation pan at the Orlando Water Plant in Orange County. Evaporation and other climatic factors at Or lando differ somewhat from those at Lakeland, but in the absence of local data, the data from the Orlando station are used in this report. A pan coefficient of 0. 7 is applied to correct the annual rate of evaporation from the pan to that from a .lake (Follans bee,. 1934, p. 705). The average, corrected, annual evaporation at the Orlando Water Plant, for the period January 1954 through
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REPORT oF INVESTIGATION No. 44 77 Uecember 1958, is 40.6 inches. This compares favorably with the c ! ata obtained from the now-abandoned Lake Hiawassee station o f the U.S. Weather Bureau, near Orlando, from 1940-1946. This a verage also seems appropriate in view of available rainfall and runoff data. Meyer (1942), on the basis of computed evaporation, produced a series of evaporation maps which showed the Polk County area to have an annual average evaporation of 50 inches ( op. cit., map no. 4). Meyer's map No. 10 shows this area to have equal mean annual evaporation and precipitation. Since considerable runoff does occur in this area (table 5), the evaporation rate proposed by Meyer is inappropriate. Transpiration is the release of water from plants during their life processes. No accurate method has been developed for meas uring the rate of transpiration of various types of vegetation in a humid subtropical climate such as that of Polk County, but transpiration is undoubtedly a significant factor in the water budget of this area. Studies by Koo (1953) indicate that transpir ation of citrus trees is very high. His study utilized test plots of 15-year old Marsh grapefruit trees, and results indicate that average daily consumption of water from the nonartesian aquifer is about 34.2 gpd/tree (gallons per day). The daily consumption varied greatly during the year. Based on this average, and 65 ! to 70 trees per acre, annual transpiration losses would be about I 30 inches per year. If allowances are made for direct re . evaporation from the foliage and land surface, and transpiration : by cover crops and weeds, it is seen that evapotranspiration rates ! in citrus groves approach open-water evaporation rates in the : area. This is also indicated by the work of Penman (1956), who 1 states that transpiration in humid climates near the equator ap . proaches a factor of 0.7 of open-water evaporation. The general close relationship of evaporation and transpiration is also stated by Blaney (1956). For purposes of this report the evapotranspira tion rate of 40 inches per year is believed to be reasonable. GROUND WATER OCCURRENCE Ground water is the subsurface water in that part of the zone of saturation in which all pore spaces are filled with water under hydrostatic pressure. It is derived from that fraction of rainfall which has percolated downward, through the soil and zone of
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78 FLORIDA GEOLOGICAL SURVEY aeration, and reached the zone of saturation. The ground water then moves laterally, under the influence of gravity, toward places of discharge such as wells, springs, streams, lakes, or the oceaL. Where hydrologic conditions permit, some of the water may move downward into other underlying aquifers. An aquifer is a formation, group of formations, or part of a formation, in the zone of saturation, that is permeable enough to transmit usable quantities of water. Ground water may occur under either nonartesian or artesian conditions. Where the upper surface of the zone of saturation, called the water table, is free to rise and fall it is said to be nonartesian. Where the water is confined in a permeable bed between less permeable beds, so that its surface is not free to rise and fall, it is said to be artesian. The term artesian is applied to ground water that is confined under sufficient pressure to rise in wells above the top of the permeable bed that contains it, though not necessarily above the land surf ace. These less permeable beds are called confining beds. The height to which water will rise in a tightly cased artesian well is called the artesian pressure head. The imaginary surface coinciding with the water levels of artesian wells is called the piezometric surface. This surf ace is generally represented on a map by contour lines that connect points of equal altitude of the pressure surface. Water in an artesian aquifer moves from areas of high artesian pressure toward areas of lower artesian pressure, at right angles to the contour lines representing the piezometric surface. Where the contour lines enclose an area of high water levels (high artesian pressure), the flow is away from the area on all sides. The artesian aquifer is being replenished in such an area. Conversely, where the contour lines enclose an area of low water levels, water is flowing into the area from all sides and is being discharged from the aquifer. Areas in which aquifers are re plenished are called recharge areas; areas in which water is lost from aquifers are called discharge areas. NONARTESIAN AQUIFER CHARACTERISTICS In Polk County ground-water supplies are obtained from four different aquifers, which were first recognized by Matson (Matson and Sanford, 1913, p. 389) . The uppermost of the four aquifers is in the unconsolidated sand and clayey sand at, -and just below, land surface. These sands cover the entire county and, together with the underlying coarse elastics where present, form the IionI
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REPORT OF INVESTIGATION NO. 44 79 " tesian aquifer. The aquifer is used for domestic supplies and tn irrigation purposes requiring relatively small amounts of wa er. Tubular wells in this aquifer range from 1 to 4 inches in diameter and from 7 to 35 feet in depth; there are also a few dug ells and pits in use. Hand (pitcher) Pumps are commonly used for domestic purposes, and gasoline-driven suction pumps are used for irrigation. The irrigation wells usually do not produce more than 20 to 30 gpm (gallons per minute), though several are known to produce 100 gpm or more. Wells are commonly constructed by driving small-diameter pipe into this aquifer. The sand is then cleaned from the pipe, and the well is deepened by water-jetting. There are very few dug, sand-point, screened, or gravel-packed wells in the county. Wells in the aquifer, as locally constructed, rarely retain their original depth because the loose sand will not stand in the walls of an open hole. The thickness of the aquifer differs widely over the county, and generally ranges from a few inches to 250 feet. However, ex treme thicknesses of 300-600 feet or more are reported along the eastern side and on the crest of the Lake Wales ridge ( fig. 4, wells 755-134-1, 801-136-2, 818-140-1, 820-140-1). Clay content,_ and hence porosity and perm _ eab~lity, likewise differ widely over the county. Figures 13 and 14 show the water levels in, and the locations of, some of the nonartesian wells in the county. Though a great : number e:xist, there were not enough to provide the amount of i control necessary for a reasonably accurate map of the water 1 table of the entire county. WATER-LEVEL FLUCTUATIONS During the course of this investigation, water levels were measured periodically in several wells in the nonartesian aquifer, i and continuous recorders were in _ stalled on others. Hydrographs ! of representative wells in this aquifer are shown in figure 15. The well illustrated in figure 1-5 is a part of the permanent net ! work of observation wells maintained in the state, and records of ! the water levels have been previously published in Water-Supply Papers of the U.S. Geological Survey under the well number Polk 47. Additional water ~ level data from wells in this aquifer in Polk County have been previously published (Stewart, 1963, table 4). Water-level fluctuations in this aquifer are due to (1) recharge 1 by rainfal}, and (2) discharge by natural gravity flow down gra
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.. l I( i E lU'L.AHATIOH . ,. . . ,,. c , t. ftll"'•tlt'hf tJth l .. h , .. ,~ ,~.., .., "~ .,. ' I" 4. L.-w i l l j U'C4l I t ::-:i,t-:., \ii~~ : =• ... ....,,."'" ...,.., a,,.., , 1 , IHI Mt,, , ..,.• 1H N I , ... , . .---,o,~ , .,.., ,,.., tt•ot ~---. =~ .,~!".. .... ,. Dl'IIIIII -~ ..... ( Y,t~r, C1n1I IS\ 4 ~.:,' ir'.t -t'!' /'J 1 1 LWfl --.. ,I I 1---T .. I I ., l J I I zroi:t'---,•,,!,~N~---.,,.,~b-11•,..,,~-=--=---:a::.• ...... ,, ... ,,. ..... _____ ..... s .... ,--.... ..1.,-,z.,.. ---~-----,-4,,--,10..--'-----,,,,""•.,,,,J Figure 18, Water-table contour of t,be Lake Parker area, June 25-80, 1956,
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....... ._ u :l '-f,c.i \.,_.,....,..., ........ REPORT OF INVESTIGATION No. 44 I O I I l 4 )Milfl 81 Figure 14. Map showing water levels in selected wells penetrating the nonartesian aquifer ( October 29, 1969 to February 4, 1960). dient to lakes and streams, evapotranspiration, downward loss into underlying aquifers, and pumping from wells. None of the wells illustrated here are affected significantly by pumping. Water-level decline due to downward loss or to natural lateral gravity flow cannot be readily distinguished on the hydrographs~ Generally water levels in wells on topographic high areas or slopes will decline at greater rates from these causes than will wells located low on topographic slopes or relatively flat locations. Recharge is reflected by rising water levels~ and the rate and amount of rise is determined by the amount of rainfall, the porosity and permeability of the aquifer, and other factors. The range of fluctuation in nonartesian wells differs widely over the county. The records of six wells, including those shown :n figures 15 and 30-32, show net . changes of 5.5 to 12.7 feet from : 1ighest to lowest levels of record in individual wells. The greatest :otal annual fluctuation ranged from 4.3 to 9.6 feet in individual wells.
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82 114 ll3 CD > CD 0 112 CD en C 111 C CD E G> 110 > 0 0 _ 109 CD CD c: 108 C) > CD 107 ._ CD 0 106 FLORIDA GEOLOGICAL SURVEY ' I .. '1 A L/1 ' I , \ \ '"' \ V\ \ IA V\ ' . \I y 1 l\1\,1\ u ' \ \ ' V ' ' , \J Well 810-136-2 1 near Hoines City I I I I ( Nonortesion o qui fer) I I I I I OS 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 Figure 15. Hydrograph showing fluctuations of the water table in a well near Haines City (810-136-2) in the nonartesian aquifer. UPPERMOST ARTESIAN AQUIFER The pebble phosphate deposits that immediately underlie the :Surficial sands of the Lakeland-Auburndale area form an artesian aquifer of undetermined thickness and areal extent which is re f erred to as the "uppermost artesian aquifer" in this report. The aquifer is in the coarse, sandy, phosphatic gravel zones (matrix) of the phosphate deposits, and is confined above by the heavy . dense clays of the Bone Valley Formation, and below by clays which may be either of the Bone Valley or Hawthorn Formations. The few wells penetrating this aquifer are located on the lowland between Lakeland and Auburndale, and are similar in construc tion to wells in the nonartesian aquifer. Near Saddle Creek the piezometric surface of this aquifer is near the level of the water .the water table. I
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REPORT OF INVESTIGATION N 0. 44 83 In the southern part of the pebble phosphate fields (Bartow iiomeland-Ft. Meade, fig. 4) the aquifer may be more productive !Jecause it is generally thicker and coarser. In that area, the piezometric surface may be intimately related to the nonartesian aquifer because. the upper confining bed is more porous than in the Saddle Creek area. Well data from the southern part of the mining area are very few. Though well data are lacking, similar artesian conditions may exist elsewhere in the county in the sands and clays generally overlying the limestone surface. Such' occur rences may be of local nature and unrelated to the geologic units present. in the Saddle Creek-Peace River mining area. Water-level observations made during the drilling of deep wells in the Lakeland area indicate that the piezometric surface of this aquifer is higher than that of the aquifers below it. SECONDARY ARTESIAN AQUIFER CHARACTERISTICS The secondary artesian aquifer which is formed in the lime stone members of the Hawthorn Formation is used much more than either of the two aquifers previously described. It is con fined above by the clays in the upper part of the Hawthorn. For mation or the lower part of the Bone Valley Formation, and is confined below by the blue clay of the Tampa Formation. The aquifer is present over much of the county south of Polk City. Along much of the northern boundary the limestones are 10 feet or less in thickness, and are soft and deeply weathered. Permeabilities in such locations (wells 805-153-2, 805-156-1, 806-156-1) are very low. Isolated areas in which these limestones have been removed by erosion exist miles south of the general boundary indicated. An aquifer within the Hawthorn Formation is also reported in recent investigations of other parts of central Florida. Bermes (1958, p~ 19-20) refers to this aquifer as the "Shallow artesian aquifer" in Indian River County; Peek and Anders (1955, p. 20), and Peek (1958, p~ 26), report a separate artesian aquifer in these limestone units in Manatee County; Klein (1954~ p. 22) likewise reports a separate artesian aquifer in the limestones of the Haw thorn Formation in the Naples area of Collier County. All of these authors find that the pressure head in these aquifers is 5 to 20 feet below that of the underlying Floridan aquifer, in the areas
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84 FLORIDA GEOLOGICAL . Sl}RVEY concerned. Peek and Anders (op. cit.) note that the difference in head appears to decrease eastward in Manatee County. In Polk County many wells draw water from this aquifer in the lowland of Saddle Creek and the Peace River, and these are used for domestic supplies and truck-farm irrigation . Others, used almost exclusively for domestic supplies, are scattered over the southern two-thirds of the county. Locally, a few large di ameter citrus irrigation wells produce large quantities of water from this aquifer. Such production is possible because these wells penetrate large solutional caverns in the limestones. Generally wells in this aquifer range from 1 to 6 inches .in diameter and from 30 to 75 feet in depth. Wells that utilize this aquifer in the southern part of the county and in the ridge sections are con siderably deeper because of the dip of the formations and the altitude of land surf ace. The casing of wells drilled into this aquifer usually terminates in the uppermost part of the limestone, but in some wells it is driven only into the clays of the overlying formations. This latter practice may lead to eventual collapse of the clays and clogging of the wells. In lowland areas, water levels in wells open only to this aquifer are generally 5 to 10 feet below the water table and are also below water levels in the uppermost artesian aquifer where it is present. 1 In the ridge areas the water level may be more than 100 feet below the water table because of the higher altitude of land sur face. Figure 16 shows hydrographs of wells which are open only to the secondary artesian aquifer. Well 744-131-1 is one of the permanent network of observation wells in use by the U.S. Geo logical Survey, and annual water-level data have been previously published in Water-Supply Papers of the Survey under the well number Polk 51. Additional water-level data has been published by Stewart (1963, table 6). The hydrographs from widely sepa rated wells in this aquifer correlate closely, and the very local effect of pumping causes only slight variations in the general pat tern of the water-level fluctuations. Locally the secondary artesian and the Floridan aquifers are in direct contact or relatively better hydraulic connection through faulting, jointing, buried sinks, areas of artesian flow, or ar~as in which the clay of the Tampa Formation is absent. The water level of the secondary artesian aquifer will equal or .closely ap proach that of the Floridan aquifer in these . areas. However, a short distance from such areas the secondary aqiiif er resumes its separate identity.
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C Cl) Ill C: C Cl) E Cl) > 0 .0 C Q) Q) C: Cl) > Cl) ... Cl) C REPORT. OF INVESTIGATION No. 44 85 Well 803-153-18, near Lakeland 108 {Secondary artesian aquifer )--+--t'------,f---+r-"'-'c...+--------1 104t-----:----t-----+------+-+----+------+-----t 1954 1955 1956 1957 1958 1959 94 92 90 88 I I r A t ; (\ )i { I l'f f r r1 I J 86 84 82 Well 744-131-1, near Frostproof 80 {Secondary artesian aquifer) I I I• I I 1949 1950 195 r 1195211953I195411955 1956 1957 1958 1959 Figure 16. Hydrographs showing fluctuations of the piezometric sul'face in a well near Lakeland (803-153-18) and a well near Frostproof (744-131-1) in the secondary artesian aquifer. THE PIEZOMETRIC SURF ACE Figure 17 is a map of the piezometric surface of the secondary artesian aquifer in the lowland along Saddle Creek in June 1956. The large cones of depression around the springs at points E, F, and G were caused by discharge from the aquifer in mine pits operating at the time of mapping. The map was made near the end of a period of extended drought (1954 through 1956). _ Much of the area between Saddle Creek arid the western branch of Saddle Creek, south of the springs at point E; is a mined-out area, used as a water-storage area in June 1956. Lime
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86 --___ _...,. __ ,....,. __ .... FLORmA GEOLOGICAL SURVEY .. .. , r ,...--5. e: . •;. ~---.::,e ... I A, IS _....,,.,._,._ ..,::_ 0 ,_ I'-• G : . '"""~ ' ; -;;--0----~ ;J _,::_ . -•-~_:_ ( ____ ___l_ .,.,.r •'"'!16" ~:c.-. """'""--'--=...,..:!---""-----,....,~=-:-'---c_...=:--. -~,,...==.-~_.., Figure 17. Piezometric-contour map of the secondary artesian aquifer of Lake Parker area (June 1956). stone of the Hawthorn Formation was exposed at many places in the floors of these pits during mining operations. Artesian springs which issued from the limestone during mining operations have been impounded. Water was pumped from the operating pits and was either used in mining operations or stored in the aban doned pits. Mining in the Saddle Creek mine (south of point E) ceased January 10, 1957. Mining in the vicinity of the more northerly springs ceased some months later. By February 1960, mining had shifted generally to the north and east of the spring sites shown and was in progress north of 804-151-7. Mining in the Orange Park mine, east and northeast of 807-154-2, began May 5, 1957, and was still in progress in February 1960. The effect of mining, and the cessation of mining, on a well (803-153-18) in this aquifer is shown by the hydrograph in figure 16. The areal effect of the cessation of mining in the Saddle Creek area, and the generally concurrent return of normal rainfall, is shown by figure 18. Water levels on the ridge are'as rose 3. to 5 feet over those of June 1956, while in .the_ Iow:Iands alo~g Saddle J
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87 . . ... .• ' !' :.:" ."==Cl -u-;/ ~ 1 •,, R).•" ~~ I ,:, ,,:."~ . : . , . f'l _'''; : ~ . f> ; ;;{ :_:_~ . . . . ;, --~~ : .~., : . ;,_:: ' ,, , , ,' ' "" . . ,, , :: ian aquifer In = dary artes -• ,_., ap of the secon .... .. --: . : .':.~ ... ,... t ic-contour m Y 1960). 8 Piezome r 9 to Februar Figure 1 . ( October 195 f t increases Lake Parker area f et and 1000 h as 15 e ' . =c I els rose as . f . a nonm1n1n Creek water ev . Frostproo is t effect of were common311 (fig. 16) locate_d :npllmping. The 1!:g the relaW en 7 44-1 d. the effects of m1~e seen , by compar1 aphs ; 8 fOOt area far b~yo~ . able rainfall malyl . in the two hydro gr . . 11 compar f the we s 18 P genera Y tei' levels o . . . 803-153f nearlier ma tive rise7f4~;1-1, and 13 feetn:~er of revisions ~e \econdary ar in well . . fl ure 18 a nu ary because of the map, In preparing f 1) Were necess the entire _area es 17 and (Stewart, !956, i: .not 'actually cov:: are made m_ fi~nor f,iu)t. tesian ~qmt\h:llght. Thes; chan: possible e":tefs':~ly the upper as original Y f intense erosion an Formation ,~ oc few wells pre18. Becau~e o tone of the Tamp~s very thin m a which are now ing, the !Imes The Hawthorn. . Hawthorn, anhd econdary and m ost limestone. t be entirely in n to both t e s h ght o . Us, ope . . h viously t ou multi-aqmfer_ we . uifers. . . . . er leVels m t _e known to be I . 'dan artesian _ . aq . ltitudes of wat . Such data ,e underlying F ~ri a inap showmf \f 1959~60, where . Figure ~9 . 1s . winter mont s aquifer during the
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88 FLORIDA GEOLOGICAL SURVEY __ ,zo--i ... ~.::r:.. :1'"----... _ .. . ... ... ,o' 0 ,., Figure 19. Piezometric-contour map of the secondary artesian aquifer (October 1959 to February 1960). available in the county; The map also shows the approximate northern extent of the aquifer. Water levels declined from 0.5 to 3.4 feet in eight observation wells during the period. The map shows that an extensive trough exists in the piezometric surface along the Saddle Creek-Peace River valleys, and that it passes between several significant piezometric highs, which indicate re charge areas. A very extensive piezometric high underlies the west flank of the Lakeland ridge, and occupies much of the south western part of the county. Another high underlies a broad flat area south of Lake Buffum. A smaller high area is located on the ridge north of Lake Ariana. AREAS OF ARTESIAN FLOW Flowing artesian wells in this aquifer existed as late as 1948 in the general vicinity of well 803-152-2, about a half a mile northeast of the U.S. Highway 92 bridge over Saddle Creek. Water
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REPORT OF INVESTIGATION No. 44 89 levels in that area were reported to have been about 2 feet above land surface in 1~48, but they had dropped to about 11 feet below the surface by 1956. In 1959 they clqsely approached land surface for brief periods, and generally were about 2 feet below land surface. The area of artesian flow apparently extended about three-fourths of a mile on either side of Saddle Creek; its north south extent is unknown. The area of flow was described by. Sellards and Gunter (1913, p. 263), and Matson and . Sanford (1913, table facing p. 390) reported a flowing well in this area. It is likely that flowing wells could be obtained along the valley of the Peace River from the southern county line north midway to Lake Hancock. Observations of ground-water leakage in the secondary aquifer in the vicinity of well 745-147-1 (fig. 19), in August 1958, showed that water levels rise rapidly toward high ground up the valley wall, and the area of artesian flow may be less than 100 feet wide in some places. Progressively lower flow and head may be expected upstream; and in the vicinity of Lake Hancock, wells probably would only flow during brief periods of very high ground-water levels. WATER-LEVEL FLUCTUATIONS The range of water-level fluctuations in wells in the aquifer differs widely over the county. The causes of the greatest fluctua tions are due to recharge and to pumping from the aquifer. The hydrographs of wells show net changes from highest to lowest water levels of record of 9.4 to 24.5 feet in individual wells. The maximum annual fluctuation in these wells ranged from 7.3 to 17.9 feet. FLORIDAN AQUIFER CHARACTERISTICS The principal aquifer in the area of this investigation is the Floridan aquifer, which consists of . a series of limestones that range from middle Eocene to Miocene in age. It is an artesian aquifer and is the source of all major public, industrial, and ir rigation water supplies in the county. The name Floridan aquifer was introduced by Parker (Parker and others, 1955, p. 189) to include "parts or an of the middle Eocene (Avon Park and Lake City limestones), upper Eocene ( Ocala limestone), Oligocene (Suwannee lime~tone), and Miocene . . (Tampa limestone _ and per
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90 FLORIDA GEOLOGICAL SURVEY meable parts of the Hawthorn formation that are in hydrologic contact with the rest of the aquifer." According to Cooper, Kenner, and Brown (1953, p. 17), this aquifer "underlies almost all of Florida, the coastal area of Georgia, and the southeastern most parts of South Carolina and Alabama." In Polk County the youngest (uppermost) member of the Floridan aquifer in a few areas is the limestone units of the Tampa Formation. In the northern and eastern parts of the county, the uppermost limestone member of the Floridan aquifer is the Ocala Group, most commonly the Crystal River Formation (fig. 5). In the remainder of the county the Suwannee Limestone is the upper member of the aquifer, although local thin limestones of the Tampa may be found. Wells penetrating the Floridan aquifer range from 2 to 30 inches in diameter and from 60 to 1~400 feet in depth. \'Yells that are open to both the secondary artesian aquifer and the Floridan aquifer are multi-aquifer wells. They range from 3 to 12 inches in diameter, and from 70 to 850 feet in depth. Most of them are small diameter and are used for domestic and small irrigation requirements. Water levels in multi-aquifer wells are about the same altitude as those in wells open only to the Floridan aquifer. This is due to the higher permeability of the Floridan 1 aquifer. Unklesbay (1944, p. 13-14) reports that in Orange County the formations constituting the Florida aquifer act hydrologically as a unit, and that water levels in the upper part of the aquifer are the same as those in the lower part. Bermes ( 1958, p. 21) reports that the aquifer also functions as a hydrologic unit in Indian River County, on the Atlantic coast. Stewart (1959, p. 33) re ported similar conditions in northwestern Polk County. Peek and Anders (1955, :p. 15), and Peek (1958, p. 26), report the existence of low permeability zones in the aquifer which re tard vertical movement of water. Wyrick (1960, p. 27-28) shows extensive stratigraphic barriers within the aquifer in Volusia County. Bishop suggests that significant stratigraphic barriers also exist in the aquifer in Highlands County. Table 7 is a compilation of water-level measurements made in Polk County. These data do not show significant changes in static water levels with increased depth of drilling in the Floridan aquifer. This indicates that the various formations comprising the aquifer have a free hydraulic connection, and that they func tion as a single aquifer. The changes actually observed and re
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REPORT OF INVESTIGATION NO. 44 91 corded are caused by ( 1) measurements being made immediately after drilling or bailing and before the water has recovered to a static level; (2) penetration of significant solutional features; (3) measurements made when open-hole portion of the well is only a few feet (80'5-155-2) ; or ( 4) well terminates in a local zone of very low permeability (as in the 210-219 foot interval of 803-156-11 and in the Lake City and Oldsmar zones of 801-200-3). The bottom of the Floridan aquifer, and hence its thickness, has not been previously determined. At the present time only a few wells penetrate the Lake City Limestone and deeper f orma tions in this county. However, the existence of highly soluble gyp sum and unaltered anhydrite, in the Oldsmar, Lake City and lower part of the Avon Park Limestones, discussed earlier in this 1 report, show conclusively that there has been no appreciable ground-water circulation in these units since their deposition. Vernon (1951, p. 87, 90-91) indicates that these minerals are common in the Lake City and Oldsmar, and ( op. cit., p. 82-85) in the underlying Cedar Keys Limestone (Pale _ ocene) and upper part of the Lawson Limestone (Upper Cretaceous). Hence, the bottom of the Floridan aquifer in the Lakeland area, and probably most of Polk County, coincides with the base of the Avon Park Lime stone. It appears that this may also be true in many other parts of peninsular Florida. THE PIEZOMETRIC SURF ACE Figure 20 is a contour map of the piezometric surface of the Floridan aquifer during the period October 1959-February 1960. During the period of measurement water levels in the aquifer were recorded continuously in seven wells, and measured periodi cally in 17 others. The net changes observed during the measure ments are indicated on the inset map on figure 20. With the exception of about 10 city wells, all of the pumping wells shown on the map are industrial or citrus irrigation wells being pumped for l~ng periods of time. They are therefore capable of exerting great influence on the water level of surrounding areas. The areas of drawdown shown around the pumping wells are approximate in most instances, and are intended to illustrate areas of generally heavy pumpage. The piezometric surface of the Floridan aquifer in Polk County is a very irregular dome-shaped surface, and is highest in the north-central part of the county (fig. 20). The dome is elon
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TABLE 7, Wate1 levels observed during drilling operations (Aquifer: 1, nona1•tesfan: 2, secondary artesian: 8, Floridan: 4, uppermost a1•tesfan) usos Date of Depth of woll Popth to water Gaoloi:,;lo well meaauroDepth of caalnir below hm1l number ment (feat) (foot) surfaoo (feet) Aquifer formation Remarks 730-120-1 o7-50 320 l,07lS 22,0 3 Luke City FOB well number W-28~2, measured b~ E. w' Bishop Oeologlat,Florlda Oeoloirloal urvel' 0-16-60 320 1,105 23.0 3 do (Bishop, 1066 p, 108) 0-21-110 3~0 1,130 23,0 3 do 0-28-50 320 1,180 22,7 3 do 106-50 320 1,210 21.0 3 do i 767-155-2 12-29-54 04 270 113,0 2 Hawthorn 12-30-54 04 281 148 7 3 Suw11,nnee 800-159 . 0-28-54 71 74 5 20 4 Bone Vnlley FOB well number W-3420 6-30-54 02 90 7.59 2 Hawthorn 7-13-54 120 178 54.42 3 SuwADnoe i 7-22-54 148 265 54.42 3 CryatBI River 801-200-3 12-14-59 32 185 5,75 2 Ho.wtliorn Also, open to 0111,,fc unit, Tampa formation g 12-17-59 520 547J,4 42.00 3 Avon Park Cavities from 4 O to 445 feet and 540 H to 12-23-59 701 711 40.34 3 do 54nifeet, 0 12-30;59 750 754 39,38 3 do 011,,ity from 729 U to 731 H feet s l• 2-60 778 788 39,57 3 do 16-60 778 887 40,50 3 do E=i 1-60 1,070a 1,135 43,7 a Lake City 1-25-60 1,076 1,358 48.9 3 . do 1~30-60 1,076 1,648 53.6 3 Oldamu.r 00 2' 4-60 l,076~ 1,808 52,0 3 do ; 2-. 8-60 1,070 1,842 42,9 3 do After 2 days roat 2-15-60 652 1,842 40,0 3 do 2-15-60 590 1,842 40.8 3 do 2-15-60 32 1,842 30.7 a do ~ 802-153-4 12-31-54 50 59 20.4/l 2 Hawthorn .. 11.:.54 56 130 28.0 a Suw11,nnee 803-151-0 10-20-54 30 155 11.10 3 Suw11,nnee 10-26-54 36 167 10.80 do 10-27-54 36 167 10,63 3 do After )Vcll at rest overnight . 10-27-54 36 176 10.84 3 do ' : 10-27-54 30 193 10.04 3 do 10-29-54 36 193 10,71 3 Crystal River? 803-153-30 11.:17 .. 54 48 275 19.39 2,3 Crystal River u.;18:-54. 809 310 51? 3 do 11-19-54 809 323 24.50 a do .. 11~23~54 365 24.18 a do ... Beforq .P.~iling '•
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11-28-54 848 369 23.00 3 Williston? . After bo.illns 11.:.23.54 348 378 23.15 3 Williston Do 12-28-54 871 372 30,9 3 do WBter lovel reported by drlllor 12-29-54 42 372 20,55 2,3 do 12-29-54 21 372 22.31 2,3 do 803-1.!56-11 10-11-55 68 84 14.315 2 Hawthorn FGS woll number W-3773 10-11-55 86 86 2 do 10-1:1-55 87 100 35.35 3 TBmpa Interbedded blue clay and limestone 10-1'2-55 87 150 36.75 3 Suwannee Before bailing, after drilling 10-12-55 87 170 37.15 3 do Do 10-12-55 87 206 30.80 3 do After one boiling 10-55 87 207 35.18 3 do Idle one-half hour l)rior to moaslirement 10-13-55 87 21o}S 39.08 3 do Ei~hteen minutes after stopped 10-14-55 87 211 38.70 3 do Be ore work started 10-17-55 If. 219 38.63 3 do Fifteen minutes after bailing toe, 10-17-55 219 39.11 3 do After drilling and bofore baUina; O 10-24;.55 87 219 36.07 3 do Thirty-five minutes after bailing ~ . 10-25-55 87 219 35 . 70 3 do Just ferior to dynamitin~ with 4 sticks 10-25-55 87 219 38.79 3 do Eigh en minutes after ynamiting well , 10-26-55 87 260}S 39,91 3 do 10-26-55 87 273 40.40 3 Crystal River After drilling, before bailing J0-27-55 87 320 40,07 3 do Do 1-1 10-31-55 87 328 38.50 3 do After 2H days idle ~-, 803-157-2 1-18-55' 228 275 110.20 3 Suwannee? 1-18-55 261 34r llO.O 3 Crystal River C'll 805-1515-2 11-28-55 0 10 6.0 1 Surface sand FGS well number W-3766 11-28-55 29 34 3.86 1 do 122-55 58 58 0,73 2 Ha.1vthorn Well idle 24 hours 12~513 60 71 11.40 2 do (Also open to Tampa. blue olay); well idle do.ye 9 125-55 60 89 26.5? 2,3 Suwannee By popping z 125.55 60 104 18.5? 2,3 do Do 125-55 60 124 19 . 5? 2,3 Suwannee By popping 125.55 00 160 17.6? 2,3 do Do 125-55 60 180 19.3 2,3 Crystal River Do 1~ 6-55 60 200 17.75 2,3 do Well idle 16 hours 126-55 60 225 18.08 2,3 do t 126-55 60 252~~ 18.01 2,3 do Work terminated 15-56 60 252 18.50 2,3 do Work resumed-111oasurement bofore work 15-56 252 257 34.80 3 star.tad . do 15-56 252 268 33.06 3 do 16-56 253 278 20.25 3 do Well idle 15 hours 16-56 253ij 311 22,42 , 3 do Well idle 30 minutes 16-56 255 811 32,8 8 do After heavr bailing 16-56 255 311 22.20 8 do Work terminated; well idle 30 minutes 2'-10-56 60 811 19.16 2,3 do 2-27-56 82~ 255 24.85 8 do LowercIEart of well collapsed or bridged 2-27-56 82 255 24.36 3 do Well i c 35 minutes ~ .
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TADLFJ 7 (Continued) (C USOR Date of Depth of c1u,l11a Jlo11tli of well Depth to wuter Ouolonlo well m eaa II rebolow lunil number ment (feet) (lc11t) (feet) Aqulfur format on nemarka 8015-1150-2 12-27-1515 20 28 6,82 4 Bone Valley FOR well number W-37611 12-27.155 20 4Oi 7,23 2 IIu.wthorn 12-27-1515 40}6 82 16,16 3 'J'ampa? After 115 mlnutea reat; cavity from 77 to 81 feet 800-11515-6 12-14-M 20 35 7 l Sand FGS well number W-3423 12-14-64 60 72 10,85 2 Caloareoua sandstone 12-U.:a.4 00 83 12,10 2 Hawthorn 12-14-M 8-1 104 11.4 2 do Well Idle 10 minutes 12-14-54 8-1 120 10, 7 2 do 807-154-3 1-23-50 53 60 7.55 2 Hawthorn Well Idle 10+ hours; FGS well number W-3826 1-23-50 153 72 lll,52 2,3 'rampa g; 1-23-56 53 02 11.07 2,3 Suwannee Well Idle 2 J• hours 1-24-150 53 117 12.10 2,3 do Well idle 1 hours 1-24-li0 53 180 13.li0 :.i,a do Well idle 17 minutes; top of Cryatal River 1-24-50 53 180 13.45 2,3 Cryatal River Well idle 1 hour 1-26-56 53 188 13,25 2,3 do Well ldle 17 hours e 1-56 53 210 13,52 2,3 do After baUinir 1-26-56 ll3 276 13.60 2,3 Williaton Well ldle 17 minutes 1-26-56 53 317 13.30 2,3 Inglis Well idle 16 hours 1-26-56 53 345 13.00 2,3 do After b~llln,r l"/l 1-26-56 63 352 13,47 2,3 do Well idle 23 minutes 1-26-56 63 360 13,42 2,3 Avon Pork a 1-30-50 63 360 13.15 2,3 do Well Idle 3~ days 1-3~-56 53 411 13,32 2,3 do Well Idle 7 minutes ' ,' na 11 809-147 2-18-50 100 8.23 3 Crystal River Measurement by E, W, Bishop, Florida Oeo2-20-50 350 8,60 3 Avon Park loaioal Survoy; FOB well number W-4275 113 2-21-56 113 465 8.10 3 do 2:..21-56 113 490 8.40 3 do 2-22-56 113 528H 7.80 3 do Cnvorn from 403 to lill feet 809-148-2 3.57 47 88 40,0 ,j Bono Vnlley? All meuurement.a by F, W, Meyer; U.S,G,S,; Ho.wthorn clay FGS well number W-6045 67.59 94~, 95 51.04 4 6 8-50 101 109 80,1 'l'o.mpa clo.y 68-59 101 124 61.00 do Top Floridan aquifer o.nd Crystn,l Rlvor Inglis formo.tlon from 15 to 126 feet 69-59 101 200 52,35 3 ..
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0-10-50 101 490 51. 3 Avon Pnrk 6-15-59 120 lilOH 51.25 3 do 810-144-1 77-oO 40 '22 7.00 ,i? UrulllTorontintod Monsurcmont mndo boforo work etn.rtod; nil moosuromonts m11do by F, \V, Moyor; FGS well numbof W-4000 77-50 83 85 JU.a:& t;iu1dt.1 uml cl~YH Aftor 30 minutes of rest 7:. 7-59 83 85 10.20 do After 39 minutes of rest 77-59 83 85 10.22 do After 41 minutes of rest 77.59 83 85 9,76 ... do After 57 minutes of rest 77-59 lOlt~ 121 16.31 3 Cryst11ol River After 14 minutes of rest 7.:. 7-59 101 i 15.68 8 do After 20 minutes of rest 77-59 101~ 151 10;97 3 Williston After 16 minutes of rest 7-7-59 101 151 10.03 8 do After 21 minutes of rest 78-59 101 181 6,91 3 Inglis Before work st11orted i 78-59 101 217 10.20 3 Avon Park After 24 minutes of rest 78-59 lOJ 217 10.10 3 do After 26 minutes of rest 78-59 101 217 10.00 3 do After 28 minutes of rest 78-59 101 220H 8,43 3 do After 46 minutes of rest 78-59 101 220H 8.36 3 do After 50 minutes of rest 1-3 78-59 101 220H 8 . 32 3 do After 52 minutes of rest ' 78-59 101 22ou 8.27 3 Avon Park After 55 minutes of rest 0 78-59 101 24.9 7,57 3 do After 81 minutes of rest "JJ:1 7.:. 8-59 101 249 7,41 3 do After 63 minutes of re.st 818-149-1 1-31-59 20~i 26 11.62 1 Cl11oyey s11ond After 18 minutes of rest; FGS well number W-5046; all measurements made by F. W, 40 Meyer rn 1-31-59 46 20.5 1 Sand After 10 minutes of rest 2-.2-59 4.0 25 4.10 1 do Sand heaved into well, before work stnrted 2.:. 2-59 65 65 7.9 1 Sand and clay 22-59 77 20 9.14 1 Snnd Sand henved into well, before clennout 23-59 77u 90 13.68 3 Ci•ystnl River After 32 minutes of rest 23-59 77 90 7.50 3 do 6 28-59 77 i 90 4.02 3 do z 79:.59 77~ 90 2,57 8 do Before work started 70-59 77 136H 4.21 a lnilia After 84 minutes of rest; from 126 to 130 ~i . feet cavern fill, sand nnd olay 7-10-59 1n~ 1asH 2.72 3 do From 136 H to 156 H feet cavern fill of sand; before work started . 7-10-59 77 145H 4,liO 3 do In honeycombed limestone; after 68 minutes or rest . :t 7-10;.5g 77 145H 4.65 3 do After 71 mlnu~es of rest 92-59 77H1 129 2.88 3 do All mensurements made by author; sand flllod well to 129 feet; beforo work stnrted 92-59 1n, 156 7,16 3 Avon Park After 67 minutes of rest 92-59 77 211H 3.10 3 do After 65 minutes of rest 818-201-1 7-31-59 18 35 2.00 3 Suwnnnoo All measurements made bi authori meaaure, 1 ments after bolling; •GS wet numbor W-5352 7-31-59 3DH 70 3.00 3 do Measured nftor b11iling 01
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co TABLE 7 (Continued) c,, usas Date of Der,th to water Oeolo1l0 well rneuureDepth of oa,dna Depth of well below hrnd number ment (feet) (feet) 1111rfaoe (foot) Ariulrer formRtlon Remarka 813-201-1 '1-81-50 ao•i 74 2.60 a do After 54 mlnutea of reat (Cont'd) 88-50 so• 100 2,20 a do Before work started 83.,50 30.i 160 2,45 a Crystal River After 5 minutes of reat 83.09 so., 20.5 2,83 3 Inills After 6.5 minutes of rest; from 10,5 to 200 feet no outtlo~eturned; from 200 to 210 feet 2.88 3 do honeyoom few outtfop 88-50 SOH 245 Alter 14 mJnutea of rest; from 234 to 235 feet 2,23 3 do oavii; few outtlnp i 84.59 30.i 24,5 From 44 to 245 feet cavity; before work atarted 84-60 sou 252 2,28 3 do Arter 32 minutes of rest 816-15'1 3. '1-66 41 61 6,77 3 Suwannee After balllng; FGS well number W-3820 37-66 41 103 6.08 3 crn;stal River After balling fJ 8'1-56 41 108 3,77 3 W lleton After 28 minutes of rest 87-66 41 108 3,63 3 do After 36 minute• of rest ; a-io-66 41 108 3.34 3 do Perlodlo water-level meaaurement 4-30-66 41 74 4.00 3 do Periodic water-level meaaurement; well filled to -74 feet with clay . 84-59 41 71 1.08 3 do Before work started 84-59 52 110 1.20 3 do After 61 minutes of rest 84-59 52 160 1.22 3 Inglis After 8 minutes of re,t 85-59 52 164 1.11 3 do Before work starts 85.59 52 168 1.21 3 do After 33 minutes of rest I 816-146-1 5-14-58 82 145 3,88 3 Williston Before work startedrl small cavity recortod at ll.51 8 Inglis 145 feet; FGS we number W-468 5-14.-58 82 1'15 After bailing 5-14-58 82 181 5,09 3 Avon Park After 40 minutes of rest 5-14-58 82 199 4,93 3 do After baillng 5-14-58 82 232 5,03 3 do Do 5-14-58 82 277 4,80 3 do Aft , er 13 minutes of reat 5-15-58 82 277 8.91 3 do Before work st11rted 5-15-58 82 297 li. 17 3 do Alter b11iling 5-15-58 82 312 4.18 3 do After 9 minutes of rest a.:.15.a8 82 322 4,31 3 do After 25 minutes of rest 5~16 82 332 3,89 3 do Before work started 5.:.16-58 82 389 4.82 3 do No cuttings returned; 8-Jnola cavity 5.:16-58 82 401 4.23 3 do After 20 minutes of rest; sand cavity fill fro111 389 to 401 feet ..
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REPORT. OF, INVESTIGATION NO. 44 . . . 97 gate in a northwest-southeast direction, generally following the major trends of the geologic structure and central highlands. Farther to the southeast, in southern Highlands County (Bishop, 1956, fig. 10, p. 44), this elongation appears to lose all definition. The broad northern part of the piezometric high, occupying all of the county north of Lakeland, Winter Haven, and Dundee, represents the highest part of the piezometric surface in peninsu lar Florida. From this area the surface slopes downward in all directions. North of Polk County the dome-shape of the piezomet ric surface becomes elongated along a northward trend through Lake County. Throughout much of this northern elongation, the dome is more specifically a well-defined ridge, as shown by Pride and others (1961, fig. 22). The measurements used in constructing their map were made concurrently with those for figure 20. The many troughs in the contours are believed to represent drawdown, or reduction of pressure-head, in the aquifer due to horizontal flow through fracture-controlled cavern systems. These piezometric troughs widen down-gradient. It appears that such systems are branchiate up-gradient in the Lakeland area, and they indicate integrated subsurface drainage systems (caverns) of great areal extent and influence. For example, the trough underlying Boiling Spring in Hillsborough County may be traced up-gradient to the east and northeast through the Lake Hollings worth and Lake Parker areas, into the southwest edge of the piezometric high. A broad plateau-like feature of the piezometric surface oc cupies much of the southwestern part of the county, and is gen erally enclosed by the 90-foot contour. This area is separated from the main portion of the piezometric high by a trough along the Peace River on the east, and by another broad east-west trough through the Scott Lake area south of Lakeland. The general trough along the Peace River is caused by upward leakage and artesian flow along the river valley. The trough south of Scott Lake ~ay be due to flow through solutional caverns developed along a major fracture zone and the heavy pumping indicated in that area. Figure 21 shows the piezometric surface of the Floridan aqui fer in .:northwestern Polk County in 1956. The depression in the piezometric surface along Saddle Creek is probably caused . in part by upward discharge into the secondary artesian aquifer which in turn was discharging water from artesian springs into the
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98 FLORIDA GEOLOGICAL . SURVEY eoo ' I ; ! :ric --~ --:-: --1:. :-:._c:_;-;_ , ,_,_-...,-~ ~ --t--t--+T""....._:-+--"':!!!!,,,,,--""i,----tiift---:--;-;Tl-c,:-,-!''r-+--;---,--~ ~ j ?: -1 t r . I -~ -~ -l-----,---t--.-'----t---,---~----',,--------+----.--,-,---,---~ -JIj :1 -~ ---'. !--------+---i-----,.-------'-------,,
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REP.ORT-pF INVESTIGATION No. 44 99mine pits (point E, . .fig~ 17). This is shown by the general coinci dence of the piezometric surfaces in an indefinite area along U.S. Highway 92 for about a mile on either side of . Saddle Creek. In 1960, long after cessation of such spring discharge, the general Te-entrant continues to exist in the piezometric surfaces of both aquifers, and is shown in figures -18 and 22. Figure 20 shows that. the re-entrant is part of an . areally extensive piezometric trough which underlies all of the Saddle Creek-Peace River valler in this county. This inqicates a general zone of upward leakage from both aquifers into Saddle Creek and the Peace River and the per ennial swampy areas along their courses. The altitude of the creek bed is 105 to 107 feet at Highway 92, and the creek stage ranged from 0.15 to l.90 feet above zero flow. Figure 13, a map of the water table in the Lake Parker area in 1956, is similar to the piezometric maps of the artesian aquifer~ mentioned above. The contours of the water table reflect a general trough along the creek as a result of discharge into the mine pits and the creek. Beu taU11 frcffl u. s GffJca,ml 5"'"r IODO~,e Q~•tilln ,I I -r--#• ~ ------r-----• -! , ! Figure 22. Piezometric-contour map of the Floridan aquifer in -Lake P~rke1 area (October:1959 to February.1960).
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100 FLORIDA GEOLOGICAL SURVEYAREAS OF ARTESIAN FLOW Figure 20 also shows areas in which flowing wells may be ob tained in the Floridan aquifer. The highest artesian head observed during the period of measurement was 23 feet above land surface at the public boat landing on the southwest shore of Lake Weohyakapka in the southeastern part of the county. Flow is indicated along the Peace River valley but does not extend north of Kissengen Springs. Upward leakage from the aquifers into the bottom of the river near. Lake Hancock, much of Saddle Creek, and soil zones of the valley floor during part of the year,. seems certain. The artesian pressure, however, is generally insufficient to produce flowing wells in these areas. A small area along the Withlacoochee River, in the area of limestone outcrop, is also an area of intermittent artesian discharge. Most of this occurs as diffused leakage rather than noticeable flow. The map indicates that most of the large lakes on the lowland east of the Lake Wales ridge are partially supported by upward leakage of water from the artesian aquifer, and that ground water is also being discharged into the Kissimmee River over much of its reach. WATER-LEVEL FLUCTUATIONS Figure 23 shows hydrographs of wells open to the Floridan 1 aquifer. These are wells in the network of permanent observation wells in use by the U.S. Geological Survey. Annual water-level records of these wells have been published in the Water-Supply Papers of the Geological Survey under the well numbers Polk 44 (810-136-1) and Polk 4 (759-158-1). Additional water-level data from wells in this aquifer have been published by Stewart (1963, table 7). It is evident that there is general correlation of the hy drographs, though considerable differences in the range of fluc tuation exist. Most of the deviations in correlation are caused by effects of pumping. Seasonal trends, .however, correlate well. The range of water-level fluctuations in wells penetrating this aquifer differs widely over the county. Recharge and pumping cause the greatest fluctuations in the aquifer. The records of 10 wells,. including those shown in figure 23, show net changes from highest to lowest water level of record of 2.2 to 17 .8 feet in 'in dividual wells. The greatest total annual fluctuation ranged from 2.8 to 10.6 feet in individual wells, and did not occur during the same year. In general, the least amount of fluctuation occurred in wells located nearest the top of the piezometric high, and the greatest J
PAGE 110
+6 +4 +2 0 -2 GJ -4 (.) 0 ... ::, "' -0 C 0 -0 GJ ... ... GJ -6 -8 -58 -60 -62 GJ Q) -64 C -66 Q) > Cl) -68 ... G) C :: -70 -72 -74 -76 -78 -80 REPORT OF . INVESTIGATION No. 44 101 Well 810-136-1, 5 m i les N. of Hoines City (Floridan aquifer) ' \ ' (\ Al .l~ :~ ,..., I\ . ,.. : \ w ""' \v ww -.,r \/l"v ' r }' . ~I\ { . \Vt Well 759-158-1, 3 miles S. of Lakeland (Floridan aquifer) \ ,. I ~. .-1 j ' \ : I ' ' ' I ~ ' I I I ~J l1 I I ;I l ,.. \ ; .. ) ' t l ' ' I V I I I I I I ,, I ,, ,, ,, ,, ,, !/ I ; : 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 Figure 23. Hydrographs of fluctuations -0 piezometric surf ace in a well near Lakeland (759-158.-1) and a well near Davenport . (810-136-1) in the Flori dan aquifer.
PAGE 111
102 FLoRIDA GEOLOGICAL SURVEY occurred in the areas down-gradient. The ranges of fluctuation were greatest in the heavily pumped. areas at Lakeland, Winter Haven, and at the phosphate mining area of the southwestern part of the county. WATER-LEVEL HISTORY Few data are available on water-level fluctuations in Polk County before 1948. The records shown in figure 23 constitute the longest continuous records in the county. Stringfield (1936, p. 172) lists water-level measurements made in a number of wells that were also observed during this investigation. Representative data from these wells are presented in table 8 for the purposes of detecting-long-term trends. Stringfield's measurements were made during a period that was preceded by 1 years of above-normal rainfall. The 1956 measurements were made after 2 years of below-normal rainfall, and the 8to 20foot indicated decline from 1934 is not considered permanent be cause of the substantial difference in antecedent conditions. The 1959-60 measurements were made after a year of above-normal rainfall, and they indicate an apparent net decline from the 1934 levels ranging from 0.3 feet to 12.3 feet. Figure 20 indicates that the plateau-like area in the south.i western part of the county is one of great ground-water pumpage. Such pumpage is largely associated with the pebble phosphate in dustry, and it is of relatively large magnitude and long duration. Reports of artesian flow and water-level data by. Matson and San ford (1913, p. 389-391), by Sellards and Gunter (1913, p. 263), and by Peek (1951, p. 80), indicate that water levels have de clined from 5 to 20 feet in the past 45 to 50 years in this area. Sellards and Gunter (1913, p. 364) report the water level in the Mulberry city well as being_approximately 21 feet below land sur face in 1907-1908. This well is 75S-158-2 of. this report, and it could not be measured during this investigation. However, in well 753-148-1, approximately 50 feet away, the water level was 35.3 feet below land surface on January 25, 1955, and was 30.1 on December 21, 1959; an apparent net ~ecline of 9 to 14 feet in 51 years. Such declines are largely attributed to steadily increasing pumpage by the phosphate industry. If all industrial pumpage would cease in this area; it is likely that tl)e piezometric surface would recover r~pidly. Only one well at Loughman (814-133-1) .in the northeastern part of the county showed essentially no change from the 1934
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TABLE 8, Net change in water levels in wells in the Floridan aquifer, 1984-59 ij (Water level jn feet above msl) Well no, AppBrent Altitude of WBter level observed Lenth of reoord i Well W,S,P, GenerBl net ohBnge in this investigation urinfi this number 778-0 locBtion Date Altitudc 1 DBte Altitude Date Altitude in feet Highest Date Lowest Date inves igation '0 l,:j 744-181-4 Po-41. Fro~rod 9/21/84 82 1ii2i56 11 I I 2/ 4/58 791 8.0 I I. I 10i2ai5g s2:s 8iiai56 One observation 7'/i-146-J Po-89 Ft, ea.de 0/20/84 101.8 86.9 1/22/60 . 98.5 7.8 98.0 4 /5/55-2/5/60 745-158-6 Po-87? Brewster 1/ 9/84 97,0 7/12/56 77, J 1/22/60 84.7 -12,3 88.3 10/26/50 71.7 8/15/56 4/5/55-2/8/60 756-185-1 Po-32 Mountain LBke 0/20/34 115.4 2/16/55 106,0 12/11/59 107,8 7,6 Two observations 758-145-1 Po-22 Eagle Lake 7 /23/34 122,8 8/31/58 114,0 1 12/17/59 111.81 -11.0 121:s oi'2i51 1 t I I oi'ai56 Two observations ; 801-1'48-1 Po-20 . Winter Haven 1916 135 7/12/56 128,7 . 12/ 1/59 125,8 117.4 7 /1 /55-2 /5 /60 . 802-151.a Po-11 Lakeland 8/15/84 116.0 7/ 6/56 100.1, 1957 (Well One observation (Pumpin!) destroyedJ Two observations 808-158-2 Po-10 LBkeland 2/20/84 111.0 7/ 2/56 105. 4 11/19/59 1 o. 7 4 -10.8 804-147-2 Po-15 Auburndale 3/15/84 128, 1 6/25/56 118. 7 11/28/59 128. 1 5.0 124.0 10ii4)54 Three observi. tions 805-144~1 Po-16 . Lake Alfred 7/20/84, 131.5 9/27/57 129, 1 11/ 8/59 120.7 1.8' 11i'2i50 Two observations 814-138-1 Po3 Loughman 3/16/84 98,5 11/26/57 92,7 11/ 2/59 93,8 + ,3 93,8 02.7 11/20/57 Five observations t Depths to water adjust,ed to meas~ring point and alt,itudes of this investigation z a Measurement made in 744-181-6, approximately 25 ft southeast of Po-41 0 ' Well re-worked and deepened ln 1954 , t 4 Measurements mo.de in 803-158-1 (Po-0), npproxima.te~y 40 ft southeast of Po-10 "
PAGE 113
104 FLORIDA GEOLOGICAL SURVEY measurements. That community has not grown materially since that time and there has been little change in the local ground water regimen. A part of the apparent net change in the Frost proof area may be due to heavy local pumping at the time of measurement in 1958. It seems likely that the areas of greatly in creased pumpage in the central and southern parts of the county have not materially affected the water levels near the top of the piezometric surface. In those areas, because of lowered water levels and increased hydraulic gradients between aquifers, local recharge bas been increased and is now supplying pr~~ent de mands. In the southwestern part of the county, the plateau-like snape of the piezometric surface indicates that local pumpage is nearly equal to available local recharge, and hence the general :flattening of the surf ace. In evaluating declines of water levels in the county, several other factors must be considered. First, observed declines of water levels do not constitute de-watering of the aquifer, but rather a reduction of pressure within the artesian system. Hence, should pumping cease for even a short time water levels would rise radidly as artesian pressure was restored. The water is not being "mined," or permanently removed. Second, each series of measure ments shown in table 9 show seasonal variations. In Polk County; TABLE 9. Specific capacities of wells in Polk County Well Number diameter of (gpm per foot of drawdown) (inches) wells Highest Lowest Median Average 30 2 615 136 375 1 24 5 518 51 180 228 1 20 6 2,500 31 837 1 1,039 18 8 833 139 286 1 338 16 9 2,700 59 238 1 566 1 15 5 417 78 222 1 219 1 12 31 2,500 14 120 1 2811 JO 3-t 1,000 18 100 189 8 2-t 750 18 67 1 122 1 6 20 109 6 25 1 37 1 -t 16 35 1 13 1 14.3 1 3 13 48 1 61 13.6 1 1 Includes multiple tests in some wells water levels follow the generalized pattern of decline during the winter and spring months, and rise during the summer and autumn. The preceding hydrographs and discussion of raiiges of water-level fluctuation show that water levels are constantly changing in a given well, and that the range of relatively short
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REPORT QF INVESTIGATION No. 44 105 term fluctuations is often equal to the apparent long-term net decline of the piezometric surf ace. HYDRAULICS SPECIFIC CAPACITY OF WELLS Meinzer (1923b, p. 62) defined the tested capacity of a well as "the maximum rate at which it is known to have yielded water without. appreciable increase in drawdown." He defined the spe cific capacity of a well as "its rate of yield per unit of drawdown" and stated that "the term is applied only to wells in which the drawd(?wn varies approximately as the yield. In such wells, the specific capacity can be estimated by dividing the tested capacity by the drawdown during the test." Many specific-capacity tests have been made by local well drillers. A summary of these are shown in table 9, and the test data are shown in table 10. Generally, the diameter of the open-hole portion of wells is drilled to about the size of the inside diameter of the smallest casing, and for the purposes of table 10, this is assumed to be the case in all wells for which da~a are lacking. In large diameter wells (20to 30-inch) such is not always the case. For example, well 805-153-4 was _ ~rilled to 15-inch diameter in the open hole with a 30-inch casing. It is the general practice among drillers to pump the finished well until the water is clear. In 12-inch wells, and larger, it is common practice to run the pump for 4 to 8 hours. This procedure not only clears the water, but determines the tested capacity of the well. For the purpose of table 11 it was assumed that such was the case, even though the drillers did not report the duration of the tests. The data of table 9 establish two factors of great importance to the hydrology of the county, and to the more theoretical con cepts of hydraulics and movement of water within the aquifer .. They are (1) the specific capacity of wells, and hence the trans missibility of the aquifer, are not primarily controlled by the amount of open hole in the well or the total depth of the well, and (2) they are not primarily controlled by the well diameter. The data show that some of the lowest capacity wells have substan tially more open hole than the highest capacity wells of a given diameter~ Similarly some 8-inch wells are shown to exceed 15-, 24-, and 30-inch wells in specific capacity. The .occurrence of the c~vern systems permits very localized zones of high tra:risniissibility within the aquifer, and closely ad
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T..\ttUJ 10, Spooiflo C111pn0Jtlos of wells ' Polk Count,~• m """ e en Diameter Depth D1111th Statlo w•tor of larae11t of ot Jovel below l>umplnir Bpoclllo Pu111plnir W11U 011IPI llRIIIIK wull h~lld 1urf11oo11 Dmw,lown l'U ttl ""IJ"oity tlmo numbttr (lnohea) (foot) (feet) Atlu1Cer 1 (feet) (feet) (1uim) (6'l>III por ft) (hou1) ltemark11• 80-inola w,ll,: unknown 3 748-l4S.2 30 800 52 22 3,000 130 l 76M4S.l 80 63 616 2,3 83 13 8,000 616 1 IS.loot c"vern 't"fooh w,ll,: 1,220 7 9-l 24 204 3 20 60 6,000 100 l 800-168 24 118 1,037 3 16 16 2,700 180 1 2-foot cavern 802-137-10 24 823 J ,210 3 83 48 2,436 51 1 Do 807-134-4 20 202 1,108 3 14,7 11.0 0,000 IH8 0 2-loot oavernj teat measured by USOB SOS.138 20 130 676 3 16 20,0 0,000 202 10 ! 10-inoh w,ll,: 748-148-8. 24 740 3 12 13 3,000 383 1 731-155.;2' 24 386 788, 3 100 8 5,200 060 J 18-inch cavern 751-163-8, 26 344 882 3 08 2 4,500 2,250 1 . i . 2 6,000 2,500 1 764-144-1 31 0 , G,800 l,160 1 24 820 a 128 4 4,100 1,026 1 7&."-166-2 24 380 721 3 132 13 4,000 308 1 808-184-3,5 20 804 030 3 27 32 l ,000 31 1 Total depth of oom11loted well ls 868 It lB•in'ol1 wrll,: B 744-157-2 30 824 852 3 40 0 7,500 838 1 ~: 748-148-6 24 300 800 3 23 10 6,000 375 6 Two 4-foot and one HHout oDvern 760-161-2 24 . 386 909 3 45 2J 6,000 286 1 l:'/J '161-169-1 24 . 480 880 3 40 10 3,600 350 1 tij ' 'IM-136-1 20 597 1,1115 3 22 6 3,550 502 1 802-158-1 18 203 726 3 01 13.5 2,000 148 1 One 3-loot and one 4-loot cavern ~ 803-157-1 18 203 805 3 100 11 2,750 250 1 Reports numerous 11 1mvel beds" 806-162-1 24 286 715 3 10 52 7,250 130 1 1,285 3 55 4,000 73 tO-ino!& t11tll1: 430 744-1~1-0 . 16 107 3 8 Not 2,700 >2,700 3-4 measurable '145-145-1 24 230 '169 3 8,6 21.5 4,000 214 1 ' 748-131-1 16 300 1,202 3 161 24 1,400 58H 1 Sand-filled cnvor11.11 758-150-8 20 355? 003 3 84 19 2,000 105 1 J:?o ,', 758-151-1 : 16 101 650 2,3 86 3 1,500 500 1 ' . 753-151' 20 I 96 085 2,3 28 4 2,o00 026 1 -foot onvern . : . 753.;.15s.1 16 882 764 3 82 13 2,100 102 1 ' . 164-15M, 20 88 750 2,3 60 3 2,000 83•J l ! \ ; I -~ ,, ' ,
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768-163-1 21J •H2 017 a 31 l:S 1 1 91.JU 2as l 2-[oot ciivo1ns 759-144-2 20 407 OliO 3 2 o.o 3,060 000 20 Probable 3-foot 01wc1t'IS 806-137-9 10 148 803 a 61 0,6 1,763 184 1 6-foot onvern n.nd 10-foot cnvern fill 16-ino/, ,1001111: 700 706 753.150~2 15 a 3,.1: 20 2,000. 100 1 800-155-1 20 750 1,030 8. 11 30 400 133 1 ~02-157-10 15 260 741 3 80 9 2,000 222 l 802-.157-11 18 360 750 3 75 20.5 1,600 78 1' ... 850 3 75 14 1,600 114 1 :'. 1,000 8 75 lO 1,600 160 1 1,20] 8 75 6 1,600 267 1 1,201 8 75 15 4,000 206 1 805-193:4 . 30 105 1,108 3 18 0 2,500 417• 8 Loss of oh•oulntlon 18 12 3,700 308 6 ~' 18 23 8,000 347 8 tl~inbl~ 1ooll1: 317 1,118 1,000 52,7 ~742-182-1 12 8 02 19 1 ij 742~1'50-l 20 444? 812 8 0 16 6,000 312 1 . .14a,;3 20 380 840 a 44 5 3,2,00 640 1 744-148-1 1:2 lj45 178 Not l,500 >1,500 1 8-foot onvern o : ii~~1'5~;:{ 1 1 6 I measurnble , '::11/J 337 970 3 80 6 2,000 334 8 ,•.7"=~14~3 20 871 886 3 58 5 1,500 300 1 Two 2-foot cnverns I .751-183-2 12 900 3 28 4 1,100 276 1 .:.145~5 .. 16 410 775 3 119 10 1,280" 123 1 ' 752~201-2 . 12 270 860 8 87 7 1,7dO 243 1 4-foot 011,vern plus sm11.Jlcr openings ,753.:1-84~2 i 11 790 1,068 8 135 4 1,600 400 1 11 Hone7comb'' zone , -~ :753.;150~5 1 ' 93 742 2,3 49 75 1,058 141 1 Loss o cuttings . 758-158-4 . 16 264 776 3 32 18 1,500 83.5 1 . 754~135~3 16 1,116? 1,260 3 14 14 1,000 71.5 1 ,754-185~10 408 718 3 26 41 1,000 24.4 -1 7S~147~8 12 281 731 3 50 22,6 1,212 62,9 1 754 .. 152.:.2 18 290 1,085 8 59 11 1,220 120 1 Honeycomb iono . ~152l3 18 284 880 8 61 18 1,200 66.6 1 Do : 'M7~1'.40~1 12 124 668 8 22 18 1,000 55,5 1 2-foot ca.vorn z :,-13s-1 12 107 600 8 4 12 1,500 125 1 -801.:.143.2 12 140:1: 648 2,3 27 5H 1,017 188 1 0 . ,\' 802-1'43-1 12 147 503 8 27 0 927 108 1 7-foot onvorn .. 802-143~2 12 188 810 3 27 7H 9.20 ]23 1 Loss of cuttings '802 .. 1~8-8 12 145:1: 642 3 27 1.2 972 810 1 "Well ends in series of smnll caverns" 802 .. 146 12 185 001 8 87 0 QOO 100 1 11 1,300 118 ... 18 1,500 88.5 . 802-146~2 12 155 640 3 40 15 1,500 100 10 1,600 100 18 l,'700 04,5 Well ends in lower part of Euwonnee 802-157-4 . ,, 12 '390 3 21 300 14.8 H Limestone or upper po.rt of Crysta.I River Formation. . l ii Nono.rtesia.n (2) Sooondnry (3) Florida.n t-,& da.to. are "reported" unless otherwise shown. 0 -:t
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'l'AIIUJ 10. 8pooUlo ou111wlties of wells in Polk County (Ccmtinuucl) i Plameter D~ith J'>e,?I Ii Rt .. tlo w•tor of lar1eat ol level below P111111>lni Rpeolfio Pumplni, Well oa1in1 CAI DI well i•nd 1urfaou Dra.wdown rate oapaolty tlmo number (lnohea) (feet) (foet) Ac111ifer 1 (feet) (foet) l1nm1) (1pm per ft) Ito111ark11• 804.147.2 12 81 160 2,3 12H IH 4150 300 l 80/S.146""4 12 83 6118 2,3 3U 3 000 300 1 80/S.147 12 100 IS02 3 lU l 2,600 2,IS00 I Woll u11d11111 20.loot cavoru 809,15 18 401 IS26 3 22 7 l ,620 218 I 809-,HIJ.1 llil 12:.1 ISOO 3 40 30 1,31 U •U 1 IO•inoli w1ll1: 44 I '189,,J21-1 JU 28U 1.000 3 +10.,1 10 ,2 460 '181M21-3 JU 262 J ,031S 3 +111 30 400 133 l 744-181-3 12 1,040 3 20 17 1,200 71 I I 7415-148-2 12 10+ 701S 3 0/j 15 1500 33,3 I 1,1.;1ga-1 12 284 803 3 112 7 1,200 172 I Well apparentlf eud11 in lower Cry11tu.l 74-7~1 S.2 1U7 120 300 3 23 101 7 1 ' , 1,s-it1-1 : Ri\'er formation ii 10 114 725 2,3 80 20 1,400 70 1 1.:C , 10 93 llSO' 2 27 4 100 215 l '161-148-2 10 109 788 2,3 08 10 1,600 llSO 1 I '161-li~l 12 289 812 2,3 121 10 1,2815 128,5 1 7Gl=l ' ~1 . 10 157 330 2,3 100 20 350 17,5 1 Well apparently ends in lower part of Suwannee Iimeatone or upper part of ' , 7&2-i41~ '. Crystal River Formation JO 185 710 3 59 20 1,200 00 1 11-foot cavern fill / I ; ~ 752-201:.S I 12 0-177 740 2,3 37 7 J ,700 243 1 One 6-!oot cavern and 1n11uler onea ' ' ' 16i.1~9.2 236-275 10 155 802 3 38 20 1,600 75 1 ! ' 7~13::2 10 102 720 2,3 47 , 15 2,000 133 1 7~1 1' 12 400 1,225 3 140 20 800 40 1 : 754~1,~,2: 18 652, 1,010 42 5~ 1,1,00 273 . 1 ! ' 756~13~3, 10 150 210 20 ot 1,000 >I ,000 1 lMoot ca\'oru : : ( ' ' measurable 757-J:63-3: 10 208 597 3 80 10 800 80 1 S.foot cavorn fill 757-1515-7 12 253 845 3 1715 10 900 DO l 769-143-2 12 218 662 3 14 4 1,100 275 1 Several l• and 2-foot caverns 801-130-1 10 255 1,327 3 44 30 1,000 33,3 1 801:.15/S.l' 10 120 560 a 80 Not 750 , >750 1 meaaurable 802-157-8 10 300 019 a 90 25 750 30 I soa-1,a.1 10 175 605 8 8 5 500 , 100 1 ' .. 80~147-4 12 344 616 3 44 IO 1,140 71.5 I ''Honeycomb" zono , . 8015-1~1 10 74 1&0 21,8 19 1.3 250 192 l 80~137-2 ,. 12 190 . 51SO 3 01 10 1,500 150 l l•fopt cavern fill , , :• l ' , , 8~137~7 : JO 102 490, 3 10 6 300 5Q 1 ' ; : , . ' ,. . ' ';: .. ,! '.;! ,-.. +'' ,,
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806-142-1 10 113 61'.I: 3 12 3 600 100,0 1 810-140-1 10 20 607 3 7 Not 750 >760 1 "Gro.vel" zone measurable ,, 810-153-1 10 44 396 3 11 9 1,000 tll 4 810-154-1 10 246 562 3 10 11 1,100 100 4 : .917:,;150.1 10 152 375 3 38 Not 800 >800 1 Well ends in 10-foot cavern , : : 8-inoh walla: measurable . 744.;131.2 10 538? 1,060 3 5 9 750 83,5 1144.:131-4 8 163 254 3 +1.6 Not . 750 >750 measurable ,,,744-,131-5 8 191 425 3 +1.6 2 650 325 :.,r45:i143-1 10 '0-156 852 2,3 118 15 1,2_00 80 '::-137-1 345-433 10 806 959 3 37 6 f,060 177 89-foot honeycomb zone .747-142-1 8 '108 255 2 55 20 188 40 , ,750~143-1 8 105 725 2,3 80 15 40 .~ ,,751-,143-1 8 113 465 2,3 75 15 600 40 i ,752-;142-8 '10 ,'207 750 8 57 15 l,200 80 , : ',752-,150-4. 8 105 .186 2 55 10 608 60.8 : /158-142-3 8 120 720 2,8 50 40 ,700 . 17,5 I i ,753.;149-2 10 296 . 575 3 20 2 350 175 '753-15G-l 8 375 2?,3 98 17 3'00 17,0 . '754-152~] 20 350 17,5 t-1 8 80 188 2 45 ' 2 120 60 ;, '754-159-3 8 72 230 2,3? 34 9 567 63 8 13 700 54 8 756-135-1 12 156 534 8 12 21 860 41 -201-1 8 176 671 2,3 37 1.2 500 416 Both wells started with JO-inoh co.sing, ,1, I but finished with 8-inoh to land sur'•' 1\'" ., face , : ;759-201-2 8 103 683 2,3 36 4,5 500 111 5foot cavern '802-137-1 8 121 405 3 4 6 500 83,3 ? B .,157-9 8 300 619 3 LIO 25 600 24 , , .803-,147-8 10 210 648 3 41 14,5 1,600 111 8 !.z: ',' '.806-187-5 8 92 423 3 20 Not 140 >14U 4-Coot cavern ,. t 1 ', I meo.surablo z. ; '.806-:137-0 8 107 810 3 42 30 2,100 70 0 ,810-.149-2 12 100 li47 3 32 33 1,241 37,0 0-incl, w~lla: 't , ,745-145-2 0 140 2 0 11 8•! 3.1 746-148-2 6 57 222, 2 42 10 60 6 ... 747.;200-1 0 600 2? 3 43 17 450 26,5 . : ':751;.183-1 10 625 1 ;8i8 3' 38 ]5 800 , 53,3 , •' I i 976, 3 38 35 600 17,1 754;.137.1 6 236 588 3 g 8 120 15 8 755-181-1 6 112 420 2,3 13 10 100 10 1 ~) Nonartesfan. (2) Seoondo.ry (3), Floridan 11 data are 11 reported" unless otberwlso shown, ' ,. C0
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'J'AUl.tJ 10, f.lpooiflo Cl-'PllCiiie11 of wol111 . Polk County (Continued) m .... .... = Diamuter I>u1Jth 01111th Rlatlo water Pumplnir: of 1 .. ~1nt of of level l>fllow Pu1111,ln1i 8pecifio Well caam~ c .. alnii well land 1mrf1u:e Drawc.low11 .... tu oapacitft tlme number (lncheli (tout) (fuet) A11uifur 1 (feet) (feet) (111111) (1u>m per t) (houn) Remarb• 76CM34 1 :.! 670 1,025 3 170 11 1,200 100 768-186 8 161 646 3 lti 600 1 ti 802-167-H 6 JOI 326 2,3 122 10 250 25 Well onda in Ceyatal River FormatJ011 6 231 710 3 112 500 41.0 or lower part of Suwannee IJ1neatou 802-167-15 12 Lou of outtinp 803-lM-33 0 181 570 3 24 2 ltiO 75,0 803-156-13 6 130 315 3 10 200 20.0 Well a111lllrently enda in Cry1tal River ; Formation 803-156-16 0 Jti8 388 3 57 li 125 25.0 Do 806-187 8 '1~5 1175 3 72 10 000 9().0 806-150-1 6 2 2 201, 3 105 0 125 13,Y Well apparently onda in Crystal River Formation 806-138-2 8 407 665 3 12 15 '150 30.0 Ii80'1-lM-8 6 53 4:11 2,3 14 3.4 200 8l'L6 H Meaeured by author i 807-201-1 6 88 198 3 '14 10 200 20.0 Well enda in Suwannee IJmeat.one; 238.5 foot cavern 800-153-1 6 43 3 15 11.25 300 26,6 1 l\leaaured by author SltJ-146-1 10 82 401 3 5 15 1,020 68.0 1 Measured by author; amall open cavi tinoll t111ll1: erna; well enda in 14-foot cavern fU1 42-200-1 4 10 18 . 1 4.6 10 100 10.0 H Well ia not aoreened; measured by author 748-128-1 4 168 BUS 2,3 .3 26 30 1.2 767-168-8 4 63 95 2 0 5 30 6.0 801-138-1 4 142 260 3 6 20 300 16.0 l:ll 801-202-3 4 66 90 2 ]3 8 75 9.4 I 802-151-10 4 42 325 2,3 12 3 . 25 90 27,6 .i Meaaurod by author 802-151-12 4 35 248 2,3 17.-1 4 85 21.2 3 Do 802-161-14 4 265 2,3 18.2 2,76 35 12.7 u Oo . 808-145-1 4 87 215 3 24 0.2 50 5.5 Cavern; no dimonalon a:ivou 808-146-2 4 101 155 2 18 15 100 6.7 2-foot cavern and Jou of outtiu111 ~3-161-0 4 48 230 2,3 13.7 2.0 46 23.0 u Measured by author 15,3 5.7 100 17.6 Do 808-153-20 4 60 1~: 2,8 10.1 4.3 65 15.1 1 Do " ' 803-1'68-14 4 ~5 2,3 10.3 Not 35 >36.0 .j 3-foot cavern mooaurablo 805-168-3 6 91 125 3 17 13 100 7.7 H (805-156-2 4, 82 311 3 27,0 1.6 17-, 10.6 H Well enda in lower part of Crystal Riv• . er Formation; 2-foot cavern 805-157-17 4 134 145 3 46 Not 17 1>17.0 1 Well enda in Suwannee Limcatone ' I measumblo " ' ' ); ,
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8-inoh wol/1: 747-158-1 8 03 100 759-1155-4 4 ' 261 261} 802-152-10 ' 3 55 65 803-148-o 3 . 03 100 803-151-6 167 3 36 ]93 803-153-20 3 . 59 125 804-152-2 3 45 59 804":"1.153-13 3 39 59 806-168-2 3 45 72 806-156-2 3 68 108 801-1154-2 3 32 156 808-158-1 ' 3 56 93 815-157-2 3 41 f08 '1 ~) Nonarteaian (2) Socondary (3) Floridan 1 Jl , data aro "reported" unless othen lee shown. 2 10 1 8 2 10.2 2 18 2,3 10,6 2,3 19.4 2 14,8 2 12.7 3 17.6 2,3 23.7 2 7,7 3 18.0 3 7.1 10 5 1.8 4 8.0 9.2 2,2 .6 4.6 2:8 .6 4,0 4.0 22,2 20 30 60 10 55 55 28 29 24 24 22 24 24 18 2.0 6,0 83,3 2,5 6.2 6.0 12.7 48.4 5,3 8.6 36,7 6.0 6,0 .8 1 Loee of outtinp; measured by author Measured by author; well ends in top of Oeyetal River (r) Formati,on. . Measured !>Y author; well ends in. Suwannee Limestone Measured by author Do, Do M~aured by author; Boneyoomb zone Do . . Measured by author; well ends In upper part of Suwannee Limeatone Measured by author; email caverna and muoh cavern 611
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112 FLORIDA GEOLOGICAL SURVEY jacent areas of relatively very low transmissibility. The disparity of specific capacities of adjacent wells is brought about by con ditions like that shown in figure 10. Thus, a change in drilling location of a few feet could produce entirely different hydraulic characteristics of the aquifer. VERTICAL MOVEMENT OF WATER Traverses were made in three wells with a current-meter to determine if interchange of water was occurring within and be tween the various units of the aquifer. Traverses were made under static conditions in wells 757-152-1 and 805-157-16 without de tection of vertical movement. These wells are open to all units of the Floridan aquifer. Two traverses in well 805-155-2 were made under static conditions and vertical movement of water from the secondary artesian aquifer downward into the Floridan aquifer could not be detected. The secondary aquifer in this well is 11 feet thick, and the well was open to 173 feet of the Floridan aquifer at the time of the tests. The observed difference in head at the time of drilling was approximately 6 feet. Because of the disparity in thickness and the generally observed disparity in permeabilities, the discharge of water from the secondary aquifer; down into the Floridan aquifer through the well bore was not detected. A third traverse in well 805-155-2 was also made while the well was being pumped at about 20 gpm. The pumping rate was too low to detect vertical movement in the well bore. The tests show that there is free circulation of water and equalization of artesian pressure within the aquifer in Polk County because the bard, low permeability zones in the different formations are highly fractured. PUMPING TESTS A pumping test was made in well 807-154-4 on July 9, 1956, to determine the coefficient of transmissibility of the Floridan aquifer at one location in northwestern Polk County. The co efficient of transmissibility (T) is a measure of the capacity of an aquifer to transmit water. It is the quantity of water, in gpd, that will move through a vertical section of the aquifer 1-foot wide and extending the full saturated height under a unit hydraulic gradient. Well 807-154-4 is northeast of Lake Parker. (fig. 22) and is
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TABLE 11. Hydrologic properties of limestone core samples from well 805-154-8 1 Depth Laboratory : Field (feet) aam~le aam~le Geolo1do num er num er 1rrom To formation Lithology 60 FLA 39 1 71.8 . 72.4 Suwannee Limestone, t11,n, fra.gmontal, very soft 60FLA 40 4 269 . 209.5 Crystal River Limestone, cream, chalky, coquina, soft 60 FLA 41 5 282.2 282.5 Williston Limestone, tan, granular, hard 60 FLA 42 7 317.5 317.9 Inglis Limestone, cream, granular, Avon Pa ' rk hard 60 FLA 43 g 447.5 447.9 Limestone, tan to 1rB~ highly dolomitized, very 1ar 60 FLA 44 11 619.5 511L8 Avon Park Limestone, brown, hl1hly domomitlzed, highly porous 60 l 4 'J,,A 45 1 1,001.9 1,002.5 Avon Park Limestone, white, very chalky, 60 F . LA 40 very soft ]6 1,169.5 1,169.9 Lake City Limestone, cream, chalky, with selenite impregnation, soft 60 FLA 47 17 1,386.3 1,386.6 Lake City Limaetone, tan, highly dolomi1,4 ' 77,3 tized, hard 60 FLA 48. 19 1,476.8 Oldsmar Limesf.one, ~ray-brown, li.iifhly dolomitize I with selenite 1mprognation, and gypsum and anhydrite nodules 1 Analysis by USGS Hydrologic Laboratory, Denver, Colorado. V vertical• H horizontal, a Sample was fractured at end of teat. May have made permeability too high, Dry unit Specific Specific weight retention Porosity yield (g per co) (percent) (percent) (percent) 1.87 17.5 31.5 14.0 1.53 28.8 43.8 15,6 1.09 23.8 26,8 3.0 1.52 20.9 44.1 23.2 2.32 7.5 18.3 10.8 1.98 11.3 30 . 3 19.0 1.68 29.1 41.3 12.2 1.85 13.5 35.1 21.0 2.34 10.8 19,6 8.8 2.42 15.2 15 . 4 0,2 , . ' , ' 1 '1 Coefficient of permeabiliw 'llj (gpd per aq t) 1 V 0.05 H 0.1 V 0.9 H 1 V 0.2 H 0,2 1-4 V2 i H4 V 0.0001 H 0,0006 V 12 1-3 H 11 15 V 0.4 H 121 V 15 H 19 0 V 0.000S z H 0.004 V 0.02 H 0.02 t ,-,. s
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114 FLORIDA GEOLOGICAL SURVEY open to the Williston and Inglis Formations and the Avon Park Limestone. The well is 26 inches in diameter, 1,198 feet deep, and is cased to a depth of 292 feet. During the test it was pumped by a diesel-driven turbine pump for. 8 hours at a nearly constant rate of 6,500 gpm. Total drawdown was approximately 11 feet. Com putations of the T were made from measurements of the recovery of the water level in the well. The T for the part of the aquifer open to this well was computed to be about 1 million gpd per foot. Data collected from other wells indicates that the T of the upper part of the Floridan aquifer is appreciably 1~.ss than 1 million gpd per foot, and that the transmissibility differs considerably in dif ferent sections of the aquifer. The T determined from the test of 807-154-4 is substantially higher than those determined by pumping tests in other parts of central Florida. As a result of tests near Terra Ceia, Manatee County (southwest of Polk County), Peek (1958, p. 49-56) finds the T of 100,000 gpd per foot and a storage coefficient (S) of 1.1 X 104 to be generally representative of the Floridan aquifer in that area. The tested wells, representing local well depths and construction, penetrate thick limestone sections of the Tampa Formation and Suwannee Limestone and reach a total depth of 650 feet, and are cased to 65 feet. In the Ruskin area of Hillsborough County (west of Polk County), Peek (1959, p. 47-54) determined that the T is 114,000 gpd per foot, and the S is 6.0 X 104 The test was made in wells 700 feet deep, cased to 65 feet, and open to the Hawthorn and Tampa Formations, the Suwannee Limestone, and the Crystal River Formation. Menke, et al, (1961, p. 89-95) present results of several tests in a well field west of Plant City, Hillsborough County, which is the most comprehensive series of tests ever conducted in central Florida. These tests indicate the T is 35,000 gpd per foot and the S is 5.0 X 10-:; in the Tampa and Suwannee Limestones of the Floridan aquifer. In a section composed of the Tampa Formation, Suwannee Limestone, Crystal River, and Williston Formations, T is 100,000 gpd per foot, and S is 3.0 X 104 The results of tests using different pumped wells, but essentially the same observa tion wells and the same geologic section indicated a T of 50,000 gpd per foot and S of 7.0 X 104 Deepening the wells to include all of the Ocala Group, Avon Park Limestone, and the upper 80 I. feet of the Lake City Limestone gave a T of 220,000 gpd per foot and an S of 2.0 X 10-•. The two pumped wells used in different I
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REPORT OF INVESTIGATION No. 44 115 tests are only 400 feet apart, and the data clearly show the differ ences which may occur within short distances in the aquifer. Wyrick (1960, p. 50-62) describes pumping tests in Volusia County (northeast of Polk County) in which the wells tested penetrate only 9 to 233 feet of the Floridan aquifer. In the tested area, the Floridan aquifer consists of a few feet of Williston, the Inglis, and the upper part of the Avon Park. Results of the tests show that T ranges from 28,000 to 370,000 gpd per foot, and S ranges from 1.1 to 7.2 X 104 These wells do not penetrate the dolomite zone of the Avon Park, which in Volusia County acts as an impermeable bed and blocks internal circulation in the aquifer, and thus permits the existence of differing heads in the two parts of the aquifer. The pumping test data all corroborate the general conclusions reached in discussions of the specific capacity of wells in Polk County-that the hydraulic characteristics of the aquifer are valid only at the site tested, but that they may be applied to broad general problems only with the knowledge that vast differences in these characteristics occur in relatively short distances vertically and horizontally. HYDROLOGIC PROPERTIES OF SELECTED LIMESTONE CORE SAMPLES Ten core samples of limestone from well 805-154-8, a deep core hole drilled northeast of Lakeland, were selected for laboratory analyses of hydrologic properties. These samples are generally representative of the differing Iithologies encountered in the well. Selection was also guided by apparent porosity and permeability, and the sampling attempted to range between the most dense im permeable doloniitized zones and open cavernous zones. The results of the tests, made by the U.S. Geological Survey Hydrologic Laboratory, Denver, Colorado, are given in table 11. Both vertical and horizontal permeability were determined for each sample. The dry unit weight, specific retention, porosity, and specific yield of each sample were also determined. The specific retention of a rock is the percentage of its total volume that is occupied by water which will not be yielded to wells. The porosity of a rock is the ratio of the volume of the void spaces to the total volume of the rock or aggregate sample. The specific yield is the percentage of its total volume that is occupied by water which is yielded by gravity to wells. The specific yield is equal to the porosity minus the specific retention.
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116 FLORIDA GEOLOGICAL SURVEY The highest coefficient of permeabili.ty determined from th~ core samples (field sample No. 16) is slightly less than the lowest value obtained for sand samples in this area (Stewart, 1963, table 9). This indicates that gross porosity and permeability of the limestones contributes very little water to a well, and that the very high capacity wells are supplied almost entirely by penetra tion of significant solutional features. Many of the samples tested contained visible solutional tubules or small cavities. The results also show that in 7 of 10 samples, the horizontal permeability ex ceeds vertical permeability as is generally expected in layered sediments. Horizontal and vertical permeabilities are equal in two other samples, and are nearly equal in a third (field sample No. 11). RECHARGE NONARTESIAN AQUIFER The principal source of recharge to the nonartesian aquifer is local rainfall. Because of the high porosity and permeability of this aquifer, there is only a small amount of direct surface runoff. In loi,v flat areas the aquifer is generally 3 to 20 feet thick, and with above-normal rainfall, the aquifer may become saturated in such areas. Under these conditions further recharge is rejected, and ponding and direct surface runoff occurs. In the ridge areas, ho\vever, the aquifer is as much as 250 feet or more in thickness and ponding and surface runoff do not occur except for brief periods during the most intense precjpitat.ion. Thus, recharge to the nonartesian aquifer is essentially equal to rainfall minus evapotranspiration. In much of the broad Saddle Creek-Lake Hancock lowla~d the aquifer is only 1 to 4 feet thick and surface gradients are very low. Perennially ponded swamp or marsh conditions exist over much of the area, probably due partly to upward discharge of water from underlying artesian aquifers. Though the aquifer is thicker (10 to 50 feet) in much of the county north of Lakes Lowery and Parker (fig. 14), topo graphic gradients are about 30 feet per mile, and surface drainage is poorly developed. Perennial swamps and ponds exist over much of that part of the county, and large additional parts of the area are marshy or spongy and nearly saturated except in . definite dry periods. The swampy conditions in the northern part of the .county, therefore, reflect rejected recharge.
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REPORT OF INVESTIGATION NO. 44 117 All evidence in the county indicates that the water table in the nonartesian aquifer is the true top of the zone of saturation, and that unsaturated zones do not exist between it and the rocks now known to constitute the Floridan aquifer (base of the Avon Park Limestone) . UPPERMOST ARTESIAN AQUIFER No data are available on recharge of the uppermost artesian aquifer, but it is inferred from water-level relationships that the aquifer is recharged largely, if not entirely, by downward perco lation of water from the nonartesian aquifer. LIMESTONE AQUIFERS The piezometric highs in figures 19 and 20 show that re charge to the secondary artesian and Floridan aquifers is occurring over broad areas of the county. Because these aquifers are essenti ally buried by the nonartesian aquifer and other unconsolidated deposits, recharge to them can only occur by water percolating downward through the overlying deposits. The approximate total amount of water recharging the sec ondary artesian and Floridan aquifers in Polk County may be es timated by subtracting runoff and evapotranspiration from rain fall. For these purposes the data of 1959 was used and it was assumed that there was no change in storage. In arriving at the total recharge, therefore, precipitation at the nearest Weather Bureau stations outside of the county in each of the basins were also used. Stations within the county, being nearer to the head waters areas of the streams, were given twice the weight of those outside of the county. Out-of-county stations used were Clermont, St. Leo, Hillsborough, Parrish, Wachula, Nittaw, and Kissimmee. Runoff data from table 6 were assumed uniform over the basin in the following computations. Evapotranspiration was estimated to be 40 inches per year, in an earlier part of the text. On the above criteria, the total water retained as recharge in each of the river basins in table 6 during 1959 is as follows: Alafia River basin: Area: 149 sq. mi. Runo~ 34 inches + Evap. 40 inches Loss 7 4 inches . Rainfall 75 inches Loss 7 4 inches 1 inch recharge _ 1 inch over 149 sq. mi. approx; = 2,600 mg
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118 FLORIDA GEOLOGICAL SURVEY Peace River basin: Area: 651 sq. mi. Runoff 28 inches + Evap. 40 inches Loss 68 inches Kissimmee River basin: Area: 651 sq. mi. Runoff 20 inches + Evap. 40 inches Loss 60 inches Rainfall 73 inches Loss 68 inches 5 inches recharge 5 inches over 651 sq. mi. approx.= 57,000 mg Rainfall 65 inches Loss 60 inches 5 inches recharge 5 inches over 651 sq. mi. approx.= 57,000 mg 1959 Total Recharge is approximately 116,600 mg These figures indicate that 120 billion gallons of water were recharged to the artesian limestone aquifers in 1959 over the Alafia, Peace, and Kissimmee basins. Although these figures are approximations, they are, however, believed to be of the proper order of magnitude, and it is evident that the potential recharge to the artesian aquifers is a relatively few inches of water per year over the county. As noted in the earlier subsection entitled "Streams/' difficulties in evaluating diversions of streamflow pre clude the inclusion of the basins of the Withlacoochee, St. Johns, . and Hillsborough Rivers in these computations. Much of the area of the Hillsborough River basin in Polk County is an area of ground-water discharge, hence recharge there is insignificant. However, such is not the case with the other two, and ground water recharge in those areas is a significant, but undetermined amount, in addition to that described above. The amount of potenti~l recharge in 1959 represents only a fraction of the total amount of water actually available for re charge. Considerably more water leaves the area by surface runoff and evapotranspiration than is currently going to recharge. In addition to these losses, a large quantity of water is presently being di::tcharged and wasted from the aquifer by artesian springs (located outside of Polk County) and in areas of artesian flow within the county. Although there is little that can be done to reduce evapotranspiration losses, the surface runoff and artesian discharge is available for use and therefore, constitutes an impor tant segment of the water resources of the area. The water pres ently being wasted may be used directly from the surface sources
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REPORT OF INVESTIGATION No. 44 119 (lakes, streams, springs) or it can be diverted to, or captured by, the ground-water system. As future pumpage increases natural discharge from the aquifers will decrease as a direct response to the lowering of artesian pressure and piezometric surface. When the piezometric surface in areas of artesian flow reaches land surface locally, ar, tesian flow will cease. At that time, water formerly discharged : will have been salvaged for use. One such case occurred in. central Florida when Kissengen Springs, near Bartow, Polk County, ceased to flow in, February 1950. The cessation of flow, and the causes thereof, have been discussed by Peek (1951). He found that the rate of consumption of ground water in southwestern Polk increased rapidly after 1937, and (op. cit., p. 81) that the "na tural balance between recharge and discharge was upset, and a decline of the piezometric surface resulted. The decline of the piezometric surface, in turn,. caused the discharge of the spring to decrease progressively until it finally ceased." Although na tural discharge from the aquifer can never be stopped, it can be reduced substantially below the present rate. Lowering of the piezometric surface in the Floridan aquifer will in turn increase recharge from the overlying aquifers and ultimately reduce the amount of water stored in the nonartesian aquifer. Because of the increased storage available in the non artesian aquifer, swamp areas and surface runoff will be de creased and in effect captured for recharge to the underlying aquifers. The tabulation of recharge to the limestone aquifers in 1959, shows that runoff exceeded recharge in the various drainage basins by amounts ranging upward from a factor of 3. Thus it is clear that the water available for recharge is vastly more than that required by the ground-water system to supply present de mands. The water resources of the area are not limited strictly to the amount of recharge from precipitation on the area. Water pres ently being pumped out of the ground is subsequently returned to the hydrologic system by septic tanks, industrial and sewerage plant effluents, and irrigation systems. Part of this used water goes into runoff and evapotranspiration, but a part of it also goes to recharge the ground-water aquifers and is, therefore, available for re-use. This is a greatly simplified statement of principles and conditions, however, great quantities of fresh water are as yet untapped in Polk County, and probably much of the interior part of the Florida peninsula.
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120 FLORIDA GEOLOGICAL SURVEY SECONDARY ARTESIAN AQUIFER The piezometric map for this aquifer (fig. 22) is not adequate for defining the recharge areas, and the contours are highly inter pretive and generalized. However, the map does indicate four piezometric highs, or recharge areas, which are partly associated with the topographic ridges. Some of the lakes in the ridge areas may be the principal sources of recharge, as water from wells penetrating the aquifer near these lakes is generally much less mineralized than water from wells at a greater distance. This in vestigation has shown at least one lake in the Lakeland ridge to be recharging this aquifer in the Lakeland area. Figures 19 and 20 show that Scott Lake overlies a pronounced piezometric high of the secondary artesian aquifer, and a piezometric trough of the Floridan aquifer. The water budget for Scott Lake, pre sented later in this report, shows that downward leakage occurred in 1956 at the rate of about 5 inches per month. ! The western piezometric high on figure 19, though including part of the Lakeland ridge in the Scott Lake area, generally follows the poorly-drained lowland along the western flank of the ridge in which there are few lakes and sinkholes. The southern part of this piezometric high underlies Hooker's Prairie, an exten sive intermittently marshy area. The piezometric high in the south-central part of the county includes part of the southern unit of the \Vinter Haven ridge, but most of it underlies broad, low, poorly-drained areas on the flanks of the Winter Haven and Lake Wales ridges. The rate of recharge by downward percolation of water through the confining bed into the aquifer may be determined from the approximate coefficient of permeability of the confining bed overlying the aquifer. If the coefficient of permeability of the confining beds is high enough to transmit the water under the existing hydraulic gradients in th~ given period of time, then recharge will occur. For this purpose the mathematical expression of Darcy's Law (Q == PIA) may be transposed to P == Q + IA. Recharge to the aquifer is confined almost entirely to the area of the Peace and Alafia River basins and in which the amount of recharge was determined to be about 60 billion gallons per 1 year. Thus Q = 59,600 mg/yr (million gallons). The vertical hy draulic gradient, I, is equal to the difference in head (water levels) of the nonartesian and secondary artesian aquifers, divided by the distance between the water table and the top of the second ary artesian aquifer. Losses of water to the nonartesian aquifer
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REPORT OF INVESTIGATION No. 44 121 and the confining bed may be disregarded in long-term considera tions, . and other discharge from the nonartesian aquifer has already been accounted for. The area of the two basins totals 800 sq. mi. However, several broad areas along the rivers are areas of flow or upward leakage, and hence not recharge areas. The area in which recharge niay occur is approximately 640 sq. m1. Therefore, ( d/ ft !! _ 59,600 mg/yr . 19 ft. 640 . 2 8 0 P gp ) 365 days "7" 65 ft. X sq. m1. X 7. 8 X 10 sq. ft/sq. m1. = 163 X 10g/d + 0.293 X 640 sq. mi. X 27.88 X 10 sq. ft./sq. mi 163 X 10g/d 5228 X 10" sq. ft. = 0.03 gpd/sq. ft. The permeability of the sandy clay confining beds is substantially lower than that of the least permeable sand in the Lake Parker area (Stewart, 1963, table 9) of 20 gpd/sq. ft. The coefficient of permeability determined here falls within the range of those of similar materials as listed by Wenzel (1942, p. 13), and which were determined by laboratory methods. The coefficient of permeability determined above, though not precise and repr~senting only a generalized summation bf the thicknesses and permeabilities of the confining beds and cover mass . over a very large area, is of the proper order of magnitude for the materials concerned. This coefficient, together with the known head relationships of the aquifers in most of the area, and the shape of the piezometric surface, shows that recharge of the secondary artesian aquifer occurs by downward percolation of water from the nonartesian aquifer through the confining beds. Undoubtedly, the coefficient of permeability differs widely over the area, as do the factors of the vertical hydraulic gradient. The coefficient determined here, therefore, may not be applicable for use in small parts of the area and precise computations. FLORIDAN AQUIFER The piezometric surface of the Floridan aquifer (fig. 20) is a large elongate dome which centers about an area in north-central Polk County. Earlier work (Stringfield, i935, fig. 3, and 1936, plate 12) has shown that the piezometric surface under the entire peninsula is essentially one large dome, with a smaller, lower dome in Pasco County. His map, slightly revised by later work
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122 FLORIDA GEOLOGICAL SURVEY and published by Unklesbay (1944, fig. 5), is shown he.re tH figure 24. Polk County lies across the highest parts of the piezo. metric surface, and figure 20, therefore, represents only the tot of the larger feature described by Stringfield. Like the secondary artesian aquifer, the rocks of the Floridar aquifer do not crop out in the area of the piezometric high bu1 are buried 40 to 150 feet or more below land surface. The smar area of outcrop in northwestern Polk and adjacent counties are hi an area of intermittent artesian leakage. The small amount of re charge which may occur in parts of the outcrop area is discharged into the Withlacoochee River soon after entering the aquifer. The piezometric high of the Floridan aquifer must, thereforei also be maintained by the infiltration of rainfall to the water table and subsequent percolation downward through the nonartesian aquifer and the underlying confining beds into the limestones of the Floridan aquifer. In much of the _ county, the Floridan aquifer is also overlain by the secondary artesian aquifer, hence, the recharge indicated by figure 20 must percolate from the non artesian aquifer, through the upper confining bed of the second ary aquifer, through the secondary artesian aquifer,through the lower confining bed ( common to both aquifers), and into the Floridan aquifer. If such recharge does occur, then the coefficient of permeability of the confining beds must be high enough to permit the passage of the quantity of water available in the space of time predicted. For purposes of computation the river basins may again be used as subdivisions of the county. In the general area of the Peace and Alafia River basins, the Floridan aquifer is overlain by the secondary artesian system, and is separated from it by the mutual. confining beds formed by a bed of blue clay of the Tampa Formation. Recharge to the secondary artesian aquifer in this area has already been de scribed. Recharge to the Floridan aquifer from the secondary aquifer, through the mutual confining bed, is indicated by the consistently higher head in the secondary aquifer and by the shape of the piezometric surface of the Floridan aquifer. The loss of some of the available water to storage and lateral moveme:Qt in the secondary aquifer during transit may be ignored. Some of this loss has already been accounted for as part of the surf ace runoff. On the basis of water going to recharg~, Q is equal to 59~600 mg/yr. The area, A, is about 640 sq. mi. The vertical hydraulic gradient, I, is the average difference in head of the
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29 20 27 26 25 REPORT OF INVESTIGATION No. 44 123 84 ~ G') C r -n 83 ,, -:"f!
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124 FLORIDA GEOLOGICAL SURVEY two aquifers, divided by the average distance between the to~s of the aquifers. Therefore, { 18 ft. } P = (59,600 mg/yr+ 365 days+ 90 ft. X (640 X 27.88 Xl0 11 ) sq. ft. 163 X IO•gpd 0.20 X (17,800 X 8 ) sq. ft. 163 X 10 8 gpd 3560 X to• sq. ft. = 0.04 gpd/sq. ft. The secondary artesian aquifer is absent in the Withlacoochee River basin and the St. Johns River basin. Recharge to the Floridan aquifer is indicated by the low local domes defined by the 130-foot contours on figure 20, and by the broad area sloping downward from them. In these basins recharge is occurring under two widely different sets of conditions. In most of the area (ap proximately 320 sq. mi.) head differentials are low, surface drain age is poorly developed, and topographic gradients are very low. The aquifer is confined by sandy clays and clays which are in turn overlain by sands and clayey sands. These basins also include the western half of the north end of the Lake Wales ridge, which is the drainage divide between the Withlacoochee-St. Johns and the Kissimmee River basins. In much of this part of the ridge the confining beds of the aquifer are missing or are represented only by a thin marl or clayey sand, and the Floridan aquifer may be under nonartesian conditions locally. Surface drainage is es sentially nil, the aquifer is overlain by great thicknesses of sand, and topographic gradients are relatively high. Head differentials between the water table and the piezometric surface are generally very low and may be zero in places. Half of the ridge section is in the Kissimmee basin, and the total area of this part of the ridge section is approximately 25 sq. mi. It is recognized that vast differences in permeability, thickness of the covermass, and lithology exist over the entire area of the basin. In the Kissimmee River basin approximately 236 sq. mi. of . the total area is an area of artesian flow or leakage, hence recharge does not occur. In the remaining 415 sq. mi., however, heac relationships and the piezometric contours on figure 22 indicatf that recharge is occurring. Of the 57,000 mg available water . in the basin, about 2,000 mg has been shown to occur in 13 sq. mi.
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REPORT OF INVESTIGATION No. 44 125 t-f the northern part of the ridge section. Therefore, about 55,000 ug is available for recharge to the Floridan aquifer in approxi1.iately 400 aq. mi. of the basin. The average coefficient of perme ability then, is f 16 ft. } P = (55,000 mg/yr+ 365 days) + \ 200 ft. X (400 X 27.88 x 10) sq. ft. = 150 X 10 gpd + { .075 X (11,000 X 10 sq. ft.)} 150 X 10gpd = 830 X 10sq. ft. = 0.2 gpd/sq. ft. In this basin there seems to be a wide difference in permeability of the covermass. The aquifer appears to be overlain by sands, slightly clayey sands, or thin sandy marls in much of the ridge portion of the basin, and by more clayey beds in the lowland areas of the basin. The piezometric surface indicates that much of the recharge is occurring on the high ridge and sand hills on the ridge flank. To summarize, the average coefficients of permeability of the confining beds and covermass of the limestone artesian aquifers in the county have been determined on an areal basis as follows: Secondary artesian aquifer. Peace and Alafia River basin area Floridan aquiferPeace and Alafia River basin area Kissimmee River basin area 0.03 gpd/sq. ft . 0.04 gpd/sq. ft. 0.2 gpd/ sq. ft. These permeabilities indicate that recharge to both of the lime stone aquifers may occur under existing conditions in the county by downward percolation of water from the nonartesian aquifer through the confining beds of the limestone aquifers. Earlier workers (Sellards, 1908; Matson and Sanford, 1913; Sellards and Gunter, 1913; Gunter and Ponton, 1931; and String field, 1935, 1936), all recognized in differing degrees, the existence of the buried artesian aquifer and probably recharge area in the central part of the peninsula. These authors concluded that the aquifer received recharge by downward percolation of rainfall in areas where the limestones were near the surface and the permeability of the over burden high enough. They also concluded that -where overlying formations were thicker and of generally low permeability downward percolation into the Floridan aquifer
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126 FLORIDA GEOLOGICAL SURVEY . would occur through sinkholes, partially filled with sand, which breached the younger formations. The concept of sinkhole r= charge was logical and, in some instances, is quite valid. The present investigation indicates that ( 1) some recharge to the Floridan aquifer does occur through sinkholes, but that this amount is a relatively small part of the total annual recharge to the aquifer, (2) recharge occurs over all areas of the county -..vhich are not areas of artesian discharge (fig. 20), and (3) the amount of recharge through individual sinkholes and lakes does not necessarily equal or exceed the amount of recharge .occurring in an adjacent nonsink area of comparable size. The total amount of recharge to the Floridan aquifer in Polk County has been estimated by drainage basins on preceding pages. It is estimated that about 25 percent of the recharging area of the county is comprised of sinkhole or sinkhole lake basins. Pos sibly 60 percent of this area, or 15 percent of the county, is comprised of dry sink basins. The areal distribution of the sinks and lakes, and the areal distribution of water available for re charge are not correlative. The Peace River basin (fig. 2) appears to contain a large majority of the sinkholes and sinkhole lakes in the county which could recharge the aquifer. However, the re charge estimates show that no more recharge occurs in the Peace River basin than in the Kissimmee River basin. It, there fore, appears that no significantly greater amount of the total annual recharge is occurring in the principal sinkhole area. Other data also suggest that widespread areal recharge is oc curring within the county. Water in the Floridan aquifer in many areas is much less mineralized than it is in principal sinkhole areas or in the area near the top of the piezometric high. Possibly the outstanding examples are near lakes in the southeastern part of the county, which is an area of general ground-water discharge. This is highly suggestive of nearby recharge. Though other factors may also influence the concentration of chemical constituents in water, the duration of contact between water and aquifer is the most significant. Some recharge to the limestone aquifers occurs from som~ of the sinkhole basins and lakes. The dry sinkholes, common h the \Vinter Haven and Lake Wales ridges, are draining water downward from the surficial sands; otherwise, they would all contain ponded water. However, the data is as yet inadequate t,) e::,tablish which aquifer is receiving the leakage. Later section, of this report will show that Lake Parker, in Lakeland, is re
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REPORT OF INVESTIGATION No. 44 127 ( 1arging the Floridan aquifer, and that Scott Lake near Lakeland j ,. recharging the secondary artesian aquifer, at measurable rates . Lake Parker is not entirely a sinkhole lake. Some sinkhole lakes are discharging little, if any, water to the limestone aquifers. Figure 12 shows the hydrographs for Lake Wire and Hollings worth, sinkhole lakes on the ridge in the City of Lakeland. The water level fluctuations of Lakes Mirror, Morton, Beulah, Hunter (Stewart, 1963, p. 106-107) are similar to those of Lakes Wire and Hollingsworth in frequency and magnitude of fluctuation. Similarly, these four lakes are also sinkhole lakes on the ridge in Lakeland. The rate of downward leakage from the lakes may be substantial if the materials filling these sinkhole basins are permeable sands. However, all of the lake levels remain relatively stable, indicating that the recharge to the lakes is enough to bal ance any downward leakage. Most of the lakes occupy closed basins that are relatively small, and range from one to three times the area of the water surface. The water levels of the lakes are at different altitudes, and range from 30 to 80 feet above the piezometric surface of the Floridan aquifer. Topographic gradients, and therefore water table gradients, within the basins are low. Recharge to the lakes from the nonartesian aquifer is small, and downward leakage from the lakes must also be small, or the lake basins would soon be dry. Many other sinks in the ridge areas, including large ones such as Lake Ariana in Auburn dale and Lake Howard in Winter Haven, appear to have similar regimens. If the Floridan aquifer receives a major amount of its re charge by the downward percolation of water through the sink! hole basins and sinkhole lakes, there should be piezometric highs under and around them. However, figure 20 shows that many of the sinkhole lakes in the Lakeland ridge overlie piezometric troughs. l t also shows other areas over the county in which ground-water levels are higher in the inter-lake areas than in wells adja~ent 1 o the lakes. Scott Lake is shown elsewhere in this report to have , 1 riginated in the Floridan aquifer, but figure 20 shows that it .3 underlain by a deep piezometric trough. Possibly a more outtanding example of a piezometric trough underlying sinkholes s shown by the piezometric surface in the vicinity of the City of .Jakeland wells 802-157-10, 11, 12, and 16, in figure 25. This igure is an enlargement of part of figure 20, and it includes a rnmber of wells which are not shown on figure 20. The City wells lppear to be drilled in a line generally perpendicular to the course
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128 FLORIDA GEOLOGICAL SURVEY aIsa aIs1 Ir) EXPLANATION well •fo! Open circle indicate~ well being pumped when meaSllled Ugper numoer 1s well number on figure 4. Lower number is altitude of water level, in feet above mean sea level. 0 /00--Piezometnc contour shows altitude of piezometric surface. Contour interval 5 feet;/ Dotwn is mean seo,o':J level. Scale in miles Boulevard JL 110 J..Q... l •Ill 28 1 Figure 25. Piezometric-contour map of the Floridan aquifer at Lakeland (November 20, 1959). of a southeast trending cavern system which passes under LakE! Mirror and Lake Hollingsworth. The water levels shown for thE! city wells were made under controlled conditions of pumpinf and altitudes were determined by spirit leveling to the nearest hundredth of a foot.
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REPORT OF INVESTIGATION No. 44 129 These data do not exclude the possibility of recharge from the lakes into the piezometric troughs, but they show that if recharge is occurring, it is at a rate too iow to create a piezometric high. There is considerable data (table 7) and reliable reported groundwater levels which indicate that piezometric troughs probably exist in association with all of the sinkhole basins. Evidence of major, widespread recharge to the Floridan aqui fer through lakes and sinkholes is still lacking. The evidence showing the likelihood and plausibility of areal recharge by slow downward percolation of water from the nonartesian aquifer, through the confining beds, in both sinkhole and inter-sink areas, is substantial. It is therefore considered that such areal percola tion constitutes the most significant method, and contributes the major amount of recharge to the Floridan aquifer in this county. QUALITY OF WATER CHEMICAL CONSTITUENTS Rainwater is only slightly mineralized but it gradually dis solves some of the soluble minerals as it percolates through the soil and rocks beneath the earth's surface. Thus, the chemical quality of ground water depends on the composition of the rocks through which the water has passed and the length of time the: water and rocks have been in contact. The quartz sand that con stitutes the nonartesian aquifer in Polk County is relatively in soluble. Limestone and dolomite, which compose the secondary artesian and Floridan aquifers, are more soluble common rocks. The uppermost artesian aquifer, composed !argeiy of quartz sand, clays, and phosphatic gravels, is less soluble than the limestone, but is more soluble than the quartz sands. During this investigation 149 samples of ground water and 10 samples of surface water were analyzed by the U.S. Geological Survey. A summary of the analyses are presented in table 12. Individual analyses are presented in the basic data report by_ Stewart ( 1963, table 8) . Analyses of water from Polk County have also been published by Black and Brown (1951, p. 94-95, 114-115, 117), Collins and Howard (1928, p. 226-227), Wander and Reitz (1951, p. 9, 11, app.), and others. Some samples were analyzed for the common chemical con stituents, and others were analyzed for only selected constituents. Results given in table 13 are in ppm (parts per million) unless otherwise stated.
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'!'ABU) 12. Range of concentration of chemical constitucntH In waters of Polk Uounty ( Chemical constituents given in parts per million) Sonarhiun V11pPr11w11t Hecontlary Jt'lorldan i Hurfacc watPr 1u111ifcr Artr111an 111111iCur Artc11ian aquifor a1111ifer Cun11tltuont Jo'rum 'l'o Fl'0111 'fo l•'rum 'fu From 1'u l•'rom 1'11 'fomperaturo ( 0 1•') 58 83 72 711 73 7'l 72 82 71 82 pl! l.3 7,7 .0 7,(1 0,8 7.3 r,.s 8.-1 0.7 IJ,I :ia, Hardno11s 1111 CaC.:01 8 ll/U ,j •l30 21,i 2:t.! 117 :mn 28-1 Di118ol ved 11olid11 t15 2:m :w 71() 21 li:H 1111 3 02 348 Specific conductance 33 381 Hl.2 02-1 30,i 737 17 72 113 500 Silica (l:510g 2.7 11 8 13 37 I.I 31 . Total iron Fo) .oo l•I (). ,, ,r,1 IJ. 02 o. 2/i o. 01 2.1 0 Calcium ( a) I •ill I o7 -1/j 18 05 15 107 M~noaium (Mg) 1.2 JO .o 15 2/i 0.-1 31 o.o 28 So um (Naj 3 11,•I J.o o.l ;j. (I 5.2 11 3.0 20 PotaBSium ( <:h . 1 2.7 () .2 0,0 0.8 0,0 4.0 Bicarbonate ( CO,) (J 218 I 205 2a2 0 337 32 353 Sullate (804) 3.2 40 () 22 1.0 0,1) 31 0.0 122 C'/J Chloride (Cl) 6,2 JO 2 I lj 20 8.0 0 26 3 32' a Fluoride cig l I 0.3 0.8 0.0 1.0 Nitrate~ I) ().0 I. Ii 0,2 (),/j 0,() 0,0 0.0 4.8 Phospl111, (1'04) 0.0 .30 0.00 0,80 0. 1-1 0.00 2. I 1),00 0.3 N111nbor or samples 10 0 :! 2U IOU (1"ro111 71 wells)
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REPORT OF INVESTIGATION . NO. 44 131 The pH, or hydrogen-ion concentration, indicates the acidity •. ; r alkalinity of the water sample. Water of a pH greater than ;.o is alkaline, and of a pH below 7.0 water is acidic. Water from ! imestone aquifers normally has a pH greater than 7 .0, but table 12 shows that the lower range of pH for water from the secondary and Floridan aquifer is less than 7.0. On~ water sample from each of these aquifers and one sample from one multi-aquifer well had values of pH below 7.0. The hardness of a water is caused chiefly by the ions of cal cium (Ca) and magnesium (Mg). These constituents are dis solved from the limestone ( CaC03) and dolomite ( CaMg ( C0 3 ) 2 ) that compose the secondary artesian and Floridan aquifers. Water with total hardness of more than 121 ppm is considered to be hard, and is commonly softened for household and certain other uses. The hardness of water from the secondary artesian aquifer in Polk County ranges from 67 to more than 306 ppm, and that in the Floridan aquifer from 40 to 284 ppm. YV' ater from wells open to both the secondary artesian and the uppermost artesian aquifers have hardness values as high as 306 ppm. Two samples of water from the uppermost artesian aquifer had a hardness of 215 and 232 ppm. The hardness of water from the nonartesian aquifer is usually less than 100 ppm, but was much higher in the analyses of samples from wells 802-156-1 and 806149-5 (202 and 430 ppm). Water in the nonartesian aquifer is greatly affected by local land use. For example, well 802-156-1 is located in the yard of a transit-mix-concrete plant, and is in fluenced by rainfall leaching cement, and percolation into the ground-water body; well 806-149-5 is located in a heavily ferti lized citrus grove. Figure 26 is a map showing the hardness of water from the Floridan aquifer. A comparison of figures 26 and 20 does not show a clear relationship between mineralization (hardness) and either distance from the top of the piezometric high or the hy draulic gradient between the wells and the piezometric high. The low hardness of water in areas distant from the top of the piezo metric high probably indicates that water is also entering the aquifer (recharging) down gradient. Hydrogen sulfide (H2S) is a gas which is held in solution in ground water. Upon exposure to air some of the gas escapes and imparts its characteristic odor of rotten eggs. The objectional odor can be easily removed from the water by aeration. Locally, water from the secondary artesian aquifer contains this gas in
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132 FLoRIDA GEOLOGICAL SURVEY 117 \ '4 \ 75 ' __ ) Figure 26. Map showing hardness of water in selected wells in the Flori dan aquifer. small quantities. Water from many wells deep into the Floridan aquifer contains noticeable amounts of this gas. However, water from the wells in the upper part of the Floridan aquifer generally does not contain the gas. Iron (Fe) differs from most other chemical constituents nor mally found in ground water, in that concentrations of only a few tenths of a part per million causes the water to have a disagree able taste and stains fixtures, laundry, the outside of buildings, and even grass and shrubbery if it is used . in a sprinkler-type irrigation system. The iron remains in solution until it is. ex posed to air, where it contacts oxygen and precipitates as an oxide. The occurrence of water having a high concentration of iron is unpredictable and may differ with depth, as well as loca tion within the county. A well that produced iron-free water
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REPORT OF INVESTIGATION No. 44 133 ~vhen first drilled may, with time and pumping, intercept water of high iron content from nearby areas. Iron can be removed fro1n water by aeration and filtration, or by use of chemical filtration or ion-exchange systems. Aera_ tion exposes the water to the oxygen in the air and most of the iron is precipitated. The water is then passed through a filter, usually sand or charcoal, where the precipitate is removed. CHANGE OF CHEMICAL QUALITY WITH TIME During the investigation four wells were sampled twice for chemical analysis (753-150-1, 804-154-8, 809-153-3, and 815157-2). In a period of about 4 years (1955-1959) water from well 753-150-1, at Bartow, decreased about 50 percent in minerali zation, and water from well 815-157-2, near Rock Ridge, de creased about 15 percent. During the same approximate period mineral content in water from well 809-153-3 decreased about 5 percent. Conversely, in 1 years (1955-56) the mineral content increased fivefold in water from well 804-154-4, on the east shore of Lake Parker in Lakeland. The change in chemical character of the water in an aquifer is related to many factors in addition to the chemical composition of the aquifer itself. Among the more important of these are length of time that the aquifer and water are in contact, the amount and rate of recharge, amount and rate of discharge, hy draulic gradient, and permeability of the aquifer. CHANGE IN CHEMICAL QUALITY WITH DEPTH Water samples were collected during the drilling of seven wells in the county to determine changes in the chemical quality of water from one formation to another and with increasing depth. Additional samples were collected from several different depths in five existing wells. The analyses of samples from 12 wells are included in the basic data report (Stewart, 1963, table 8). The results of the analyses show no significant changes in concentrations with depth in five wells. They show a marked increase in mineralization with depth in one set of drilling sam ples, and very slight increase in three sets of drilling samples. A marked decrease occurred in one set of drilling samples and one set of bailed samples. It may be noted that the data do not show a single ion or physical characteristic of water in the Floridan aquifer which changes consistently with depth or geo logic formation.
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134 . FLORIDA GEOLOGICAL SURVEY WATER TEMPERATUR~. Collins (1925, p. 101) found that the temperature of ground water is generally from 2 to 3F above the mean annual afr temperature if the water is between 30 and 60 feet below the surface of the ground, and that the approximate average increase in temperature with depth is about 1 F for each 64 feet. The average annual temperature in Polk County ranges from 72.3F to 72.7F (4 stations). On the basis of Collins' work, the water temperature of the secondary artesian aquifer would be expected to average about 74.5F, and that of the Floridan aqui fer about 84-90F. The measured temperatures of water ranged from 72F to 82F in the secondary artesian aquifer and from 71 F to 82F in the Floridan aquifer. In the nonartesian aquifer temperatures ranged from 72F to 79F, and from 73F to 74F in the uppermost artesian aquifer. Figure 27 is a map 75 80.Po,~ C,ty 73 74 N EXPLANATION I e 77 l Well --, Number is temperature of 81 \ water in degrees fahrenheit \ \ 0 10 miles ===== Figure 27. Map showing water temperatures in selected wells in the Flori dan aquifer.
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REPORT OF INVESTIGATION No. 44 135 showing the temperature of water in the Floridan aquifer as determined during water-sampling programs. The water tempera tures shown on figure 27 are the temperatures measured at the pump discharge, and, therefore, are the composite temperatures of all the water reaching the individual wells. Temperature logs were made for 12 wells in the county under static conditions, using a thermistor-type logger, and are presented in the basic data report (Stewart, 1963, fig. 3). In many wells having water levels within 20 feet of land surface the tempera ture of the water increased slightly to a depth of 40 to 60 feet. Below these depths the temperature either remained constant within several tenths of a degree or decreased slightly. In eight wells having 200 to 440 feet of open hole, the tempera tures increased overall from the bottom of the casing to a depth of 500 feet, in amounts ranging from 0.1 F to 0.9F. On the basis of these net changes the average increase with depth ranged from 0.04 F to 0.37F per 100 feet. The amount of open hole or location of well do not seem to correlate in any way with net change in temperature, or average rate of change. In four wells with 30 to 110 feet of open hole, net changes in temperature in the open hole ranged from +1 F to -0.9F ~ These wells were less than 350 feet total depth. Two of them were open only to the secondary artesian aquifer. In well 818-151-2 the temperature decreased . 1.4 F from the bottom of the casing at -63 feet to the total depth of 150 feet. This is believed to be due to effective and rapid recharge to the Floridan aquifer from the nonartesian aquifer. A slight decrease, and subsequent slight increase, was noted in wells 804-151-6, 801-156-1, and 754-151-4. This may indicate slow recharge to the aquifer where it is more deeply buried. In the case of 801-156-1, it may represent leakage (recharge) to the aquifer from nearby Lake Hollingsworth as well. It is interesting to note that the maximum temperature in these explorations at depth of 500 feet below land surface was 79.7F in well 753-158-3. However, the maximum temperature usually did not exceed 75F. SUMMARY OF CHEMICAL QUALITY The concentration of dissolved minerals in the water of the aquifers of this county differs considerably within each aquifer, and the ranges of concentration in a given aquifer over]ap those of other aquifers. __ _ ". , . .
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136 FLORIDA GEOLOGICAL SURVEY The temperature of water in the open-hole portion of wells shows little change to depths of 500 feet below land surface and seldom exceeded 75F. Samples obtained by pumping, however, ranged up to 81 F. The chemical quality of water from the limestone aquifers may change considerably within a few years because of location and rate of recharge and permeability of the aquifer. Changes in chemical quality of water with depth are inconsistent in the wells sampled, although samples from about half of these wells indicate no appreciable change to depths of about 500 feet. WATER USE Nearly all water supplies in Polk County are withdrawn from ground-water aquifers. The majority of these are furnished by wells open only to the Floridan aquifer. This is especially true of wells which are 12 inches or more in diameter, and is generally true of 8and 10-inch wells. Smaller diameter (2to 6-inch) wells may be open to either or both the secondary artesian or the Floridan aquifers. The uppermost artesian aquifer is seldom used because of high mineralization, clay content, and pollution. The nonartesian aquifer supplies a few small domestic wells and locally furnishes small irrigation supplies. Wells were classified as to the principal use of the water pro duced in compiling and estimating the 1959 water consumption in the county. PUBLIC SUPPLY Public supplies are all city and town supply wells and wells that supply recognized housing developments and subdivisions. Pumpage is not metered by many of the public water systems in the county. Table 13 shows the metered pumpage data available for the period of this investigation .. Lakeland, Highland City, Polle City, and the small communities of Sand Gully and Tancrede TABLE 13. Annual metered pumpage by municipal systems in Polk County, 1954-59 (millions of gallons) City 1954 1955 1956 1957 1958 1959 Haines City 282.19 334.93 351.69 329.26 358.85 H"igbland Park 24.90 24.34 Zl.41 22.92 21.66 22.11 Lakeland 2,133.94 2,170.03 2,412.09 2,268.342,651.42 2,561.58 Lake Wales 373.86 428.10 484.87 439.84 464.-89 W-mter&ven 931.37 1,022.64 922.26 975.77
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REPORT OF INVESTIGATION NO. 44 137 (Standard Village) near Lakeland, each have separate public water supply systems, but all of these systems are operated and main tained by the City of Lakeland. There are 13 wells in the Lake land city system, 2 wells in Highland City, and 1 each in the other communities. Total pumpage records are available from the Lake land city system beginning with 1928. The total annual pumpage of the Lakeland system is shown in figure 28. Pumpage at the other four communities is not metered and is not included. 2,800,-----------------------------, (/) z 0 :::l 1,eoo,1----,------< C> --1,600 (/) z 31~001---------------------l<+-Ji<.,4<-,L-..,L..--,''+,IL-,,<-J<.,Y,.,,.yc..,.<'--Af ., i 1,200 --"' C> t 1,0001--------=> a. 400 1928 1930 1935 1940 1945 1950 1955 1 959 Figure 28. Graph showing total annual municipal pumpage by City of Lakeland, 1928-59. Estimates of the total pumpage by other municipal systems in the county were based on data compiled by the Florida State Board of Health in 1959. These data were revised to bring them into agreement with 1960 census data and the pumpage data of table 13. A total of 85 municipal supply wells inventoried during the investigation are believed to be 95 percent of all such wells in the county. All of the water supply systems of the charted towns and cities are publically owned. A few smaller communities such as Gibsonia, near Lakeland, and those of most of the . subur ban developments and subdivisions are privately owned and op
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138 FLORIDA GEOLOGICAL SURVEY erated. The category of Public Supply does not include very small private systems used to supply only 3 or 4 homes. Also included in the general category of Public Supply aru wells which furnish water to the public at large. Wells in thfo category are those supplying motels, restaurants, and public parks. The estimated pumpage from these wells is based on a total of 59 wells inventoried. These are assumed to represent about 50 percent of such wells in the county. The total annual pumpage for public supply in 1959 are esti mated as follows : Municipal supplies _____ --------------------------------7,100 mg Other public supplies ---------------------------------62 mg Total __________________ 7,162 mg DOMESTIC SUPPLY This classification includes individual wells which supply gen eral household requirements, urban or rural. It does not include wells used only for specific non-household purposes, such as lawn irrigation, air conditioning, swimming pools, and others. The es timated pumpage is based on the 1960 census, Florida State Board of Health data, and an estimated daily per capita usage of 60 gallons. Approximately 270 wells in this category were inventoried, and these are believed to be much less than 25 percent of all such ,vells in the county. Total annual pumpage by domestic wells in the county in 1959 is estimated at 1,200 million gallons. INDUSTRIAL SUPPLY This category of wells includes those used for purely industrial purposes, and those used, all or in part, by various industries for housekeeping, air conditioning, and the like. Most industrial supplies are obtained from the Floridan aqui fer. However, the phosphate mining industry obtains considerable amounts of water from seepage into the mine pits. These pits cut through the nonartesian and uppermost artesian aquifers, and some cut into the secondary artesian aquifer. The pumpage for the phosphate industry given below includes pumpage by all mining processing, refining, and associated fertilizer plants in the county. A total of 65 wells were inventoried in this category and these are believed to be 100 percent of those in use now, or in the past 3 years. Many older and abandoned wells of this industry
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REPORT OF INVESTIGATION No. 44 139 were also inventoried. The estimate pumpage is based on pumping rates and durations furnished by the various phosphate com panies . . The pumpage by the citrus industry includes only the packing and processing phases of the industry. not the irrigation of citrus which is included under Irrigation Supply. The total pump age is based on average pumping rates and durations supplied by most of the companies concerned, and estimates for the other companies based on the furnished data. The 50 wells inventoried in this category are believed to represent about 95 percent of the active wells in the county. A number of citrus-packing companies (fresh fruit) utilize municipal supplies, their requirements being relatively small compared to the canning and concentrate plants. Ice and laundry plants are relatively large water users, but are few in number. The pumpage estimates are based on rate and duration data furnished by ice companies, and on metered pumpage data furnished by two laundries in Lakeland. Miscellaneous industrial wells include all other industrial sup plies not specifically mentioned above. For the most part, these are small systems supplying boilers, air conditioning, and fire, irrigation, and housekeeping requirements, rather than direct process use. The 35 wells inventoried in this category are believed to represent about 50 percent of the total number in the county. Total industrial pumpage in 1959 is estimated as follows: Phosphate industry Wells -----------------------------------------------Pit pum page ----------------------------------------Citrus . industry Wells for processing ---------------------------------Laundries ( using own wells) ---------------------------Ice manufacture ( own wells) ------------------------. Miscellaneous industrial use ---,----------------Total IRRIGATION SUPPLY 38,000 mg 13,000 mg 10,000 mg 23 mg 540 mg 630 mg 62,193 mg The abundant rainfall not withstanding, irrigation is normally required about once per season for the citrus crops of the county. Such irrigation is vastly greater than all other irrigation uses in the county combined because of the acreage involved and high evaporation rates. The irrigation of truck crops is more frequent,
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140 FLORIDA GEOLOGICAL SURVEY but of shorter duration and lower rates, because of multicrop yields from single fields in each year. Both ground and surface water are used for irrigation, but the largest quantity comes from ground-water sources. Most irriga tion wells obtain water from the Floridan aquifer, secondary aquifer, or both. A few farm irrigation systems use water from wells in the nonartesian aquifer, and a very few use water pumped from shallow artificial ponds in the nonartesian aquifer. The principal use of surface water is for the irrigation of citrus groves, and lakes are widely used except in the Lakeland ridge area. The estimated pumpage from wells, listed below, is based on 339 inventoried citrus irrigation wells which are believed to rep resent about 40 percent of the total such wells in the county, and 144 other irrigation wells believed to be 75 percent of non-citrus irrigation wells in the county. The estimated irrigation pumpage in 1959 is as follows: Citrus cr9ps ' 'l \ Wells -~-------------------------------8,600 mg Lakes -----------------------------------1,400 mg Farm crops "'\Vells ---------------------------------10 mg Ponds & Lakes Total irrigation use 8,610 mg (ground water) 1,400 mg (surface water) Pumpage from lakes for citrus irrigation is estimated from the number of installations observed, average capacity of the pumps used, and average length of irrigation period. The amount of water pumped from ponds and lakes for farm crop irrigation is a relatively insignificant amount. MISCELLANEOUS SUPPLIES Several other ground-water uses do not fit into the preceding general categories of wells . .They represent a relatively small part of the total county pumpage, but are none the less a part of the total. The following estimates of annual pumpage are based on 50 inventoried wells which may represent less than 30 percent of the total number of such wells in the county. Livestock and dairies ---------------------80 mg Air conditioning and swimming pools only __ 10 mg Railroads, for housekeeping use only __ _ --Total ________________ 90 mg
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REPORT OF INVESTIGATION No. 44 141 SUMMARY OF WATER USE The total estimated annual ground-water pumpage in Polk County in 1959 was 79,255 mg. Another estimated 1,400 mg is pumped from surface-water sources each year. The ground-water pumpage reduces to an average rate of about 217 mg per day, or 151,000 gpm, each minute of the year. The total annual pumpage represents the amount of water which would cover the entire county to a depth of approximately 2 inches. Total annual pumpage will vary considerably from year to year because of the amount and distribution of rainfall, particu larly with reference to citrus irrigation and municipal require ments. However, because more citrus acreage is being planted and more citrus produced, and growth in industry generally, the pumpage for industrial use can be expected to increase in the future. Continued population growth and increased municipal and domestic pumpage can also be anticipated. Note that the City of Lakeland pumped more in the wettest. year of record ( 1959) than in one of the driest years of record ( 1956), only 3 years earlier (figs. 3 and 28). Contributing to this increase, in addition to population growth, is a changing way and standard of living which utilizes more water-consuming facilities-auto matic dishwashers, clothes washers, shower baths, swimming pools, air conditioning, lawn irrigation systems, and many others. SPECIAL PROBLEMS LAKE PARKER HISTORY AND NATURE OF THE PROBLEM A local problem of considerable importance concerns the future of Lake Parker in eastern Lakeland (fig. 13). The possibility that the water level in this lake might be greatly lowered by future large withdrawals of ground water in and near the northern and eastern shores is a matter of great concern to the residents of Lakeland, to the city government,'and to industry. Lake Parker covers about 2,200 acres and is generally very shallow. Soundings made in May 1954 indicated that at the deepest point the lake was approximately 9 feet. At that point the lake bottom is approximately 119 feet above msl. The northern part of the lal<:e's. drainage basin is low and relatively flat. On the east and south sides of the lake the drainage divide is relatively close to the shore. In the southwestern part
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142 FLORIDA GEOLOGICAL SURVEY of the basin there is a steep gradient from the ridge in central and northern Lakeland. Northwest of the lake the basin widens appreciably. Small streams enter Lake Parker from a large sinkhole basin west of the lake in northern Lakeland, and from Lake Gibson and other sources northwest of Lake Parker. Several small canals enter the northeast arm of the lake from surrounding swampy areas. The lake overflows through a canal extending from the east shore into the Saddle Creek drainage system. A concrete control structure in the canal, near the lake, prevents outflow when the lake level is lower than 129.6 feet above msl. The City of Lakeland operates a powerplant on the south shore of Lake Parker, at the site of well 802-155-1. This plant, which produces 70,000 kilowatts, uses water mostly from Lake Parker for cooling the power units. The plant when in full opera tion uses lake water at a rate in excess of 108,000 gpm.l:i This usage is more than 10 times the measured yield from any well in the county and more than twice the average pumpage rate for the city system in 1959. The water withdrawn from the lake, plus a small amount used from the nearby city supply well, returns to the lake after passing through the powerplant. In order for the intake system of the plant to operate, the lake level must be more than 125.45 feet above msl. Some data concerning the subsurface geology in the Lake Parker area were obtain~d from the prospecting records of the American Cyanamid Co. and some were obtained by drilling test holes. A composite geologic section made from these data follows: Material Sand, quartz, gray to dark-brown Sand, clayey, tan to brown Clay, sandy, phosphatic, yellow to gray-green Clay, sandy, yellow to brown; phosphate pebbles Clay, sandy, brown; limestone fragments Limestone, sandy, phosphatic Thickness (feet) 2-20 5-10 5-10 3-10 1-4 This general sequence of sediments is found throughout the low land area around Lake Parker. Occasionally, in prospecting for phosphate, so-called "blank holes" are encountered. In the Saddle Creek-Lake Parker area, the :i PersomiJ communication from Mr. C. D. MacIntosh, Jr., Superintendent, Light and Water Dept., Lakeland, Nov. 8, 1960.
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REPORT OF INVESTIGATION NO. 44 143 term "blank holes" refers to test borings in which only traces of phosphate were found or in which no phosphate was found. Usu ally, sand is the only material penetrated. Prospect borings gener ally terminate just below the base of the phosphate-bearing clays, and just above the limestone of the Hawthorn Formation. "Blank holes" generally terminate at depths well below the level of phosphate deposits found in nearby test holes. In some places the mapped locations of the "blank holes" appear to follow a pattern much like a stream course. One such pattern was noted in the area in and around the northern arms of Lake Parker by personnel of the American Cyanamid Co. during the company's prospecting operations. If the thick sand sections in these patterns continue downward to the underlying limestone, they would permit much greater local leakage, or re charge, from the lake to the aquifer than would occur through the clay confining beds normally found throughout northwestern Polk County. Test hole 805-156-A (fig. 13) was drilled in the bottom of Lake Parker near the mouth of the northwest arm of the lake, in one of the deepest sand sections of the pattern, to determine if the sand extended downward to the limestone bed rock. Figure 29 shows the materials which were penetrated. The data from the test drilling indicates that the normal sand and clay sequence, found in hundreds of logs of phosphate prospecting holes in the area, probably continues under the lake. The surficial sands are not known to extend to the limestone in the area ad jacent to Lake Parker. However, this does not preclude the absence of clays from very small areas because prospecting holes are generally drilled 100 yards apart. From 1949 to July 1954, the lake level was measured by the engineers of the city light plant at a staff gage on the pier at the plant. A continuous water-level recorder was installed on Lake Parker on July 21, 1954. Figure 30 shows the hydi-ographs of Lake Parker, well 803-154-10 in the secondary artesian aquifer (fig. 17), and well 806-154-1 a multi-aquifer well (fig. 21). There is a general correlation of water-level fluctuations in the three hydrographs. Departures of the hydrograph of well 803-154-10 from the pattern of the other hydrographs was probably due to varying pumping rates in active mine pits south of point E, fig. 17. Figures 31 and 32 show the hydrographs of Lake Parker, and nearby wells in the nonartesian, the secondary, and the Fl:0rid3:n aquifer. These wells were drill~d for the U.S. Geological Survey and are located on the south side of the northeast arm
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0 10 20 0 LJ 50 co w 60 z ... I .,_ 70 a.. w 0 80 90 ........ . . . . .. : ...... : . •. . . . . . . . . ... . . ..... . . . . .: .... . . . . .. .. . . . . .. . . . . .. . . . . . . . . .... . . . . . .. . . . . . . . . . . . . . ... . . . . . . . . . . .. . . . . . . . .. . . : . . . . . . . . . ... . ..... . . . . . . . . . . . . . . . ..... . . . ... ..... . .. . . . . . : .. . . . . .. . . . ,,. ... . . . . .... . . . . . . . . . .. . . : ... . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . , . .... . ,. . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . .. . . ..... . . . . . . . . . . . . . . . ... . . . . . . . . . ... . . . . .. . . . . . . . . . . . . . . . . . . -. . . . . .. . •-.:.__-. _ .. -=--. ..!...: . . . . .. !....!.. ..:. ..:..• . . . . . _J rf:::::35=::=e Bottom elev. = 35 msl Muck, block, soupy Sond,dork-brown; much fine organic debris. Sand, light-ton; slight amount of organic material; becomes lighter colored downward. Sand, chocolate-brown; sharp contact with lighter colored sand above; much fine organic material; becomes very slightly clayey in lower 5 feet. Peat, block, porous; very little sand or cloy. Sond 1 chocolate-brown 1 slightly clayey; amount of organic matter increases below 58 feet. Sand 1 brown I lighter than above j much organic matter; becomes sli_ghtly to moderately clayey below 74 feet. Cloy, gray-green I very sandy, tough, dense; becomes waxy and has little sand below 85 feet. Clay, yellow-brown,dry, tough, greasy. Cloy, greenish-gray, sandy, gritty~ contains tough dense yellow streaks. Cloy, as above~ contains weatt\ered lime stone fragments. Figure 29. Log of sediments penetrated in test hole 805-i56-A, in Lake Parker. 144 I ,
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130r--r,r-,---,--,----,--'-:r-.-.---r--,--.-.......--.---.---,---.---,-...-,--...----r-..--.--..---,~ LAKE PABKER 128127 ..J 126 UJ > w 125 .....J 0 121 CD w U7 .J a:: 125 w 124 123 122 121 5 miles northeast of 120 Lakeland .Depth of well 130 ft. 119 Depth of casing 72 t (Secondary artesian aquifer) 118 M J J A S O N D J. F M A ..M s J A S O N D J FM A,M J 1954 1955 1956 Figure 30. Hydrograpli. of water levels in Lake Parker, and in wells 803154-10 and 806-154-1, 1954-56. 145
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146 > a .. C: a E > 0 .0 128 125 124 123 0 122~-FLORIDA GEOLOGICAL SURVEY ; Well 80!H55-3,rieor L.akeland (Secondary : 121 --•-------+---aquifer) -+----,.,.-,---+-tt----+-----:---1:---r-------1 J 1201---------------------,-----,1-----+-t--t--t-1~--,---,.y-,---t-, li7 116 112 ~------'----------''----------'-----------------1956 1957 j959 1959 Figure 31. Hydrographs of water levels in Lake Parker and in wells 805-: 155-1, 2, and 3, 1956-59.
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REPORT OF INVESTIGATION No. 44 147 C 0 e ,23 ., I l, 122 --4------'
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148 FLoRIDA GEOLOGICAL SURVEY discharge of all streams flowing into or out of the lake was meas ured once in September 1955 and agai _ n in February 1956 by the Surface Water Branch, U.S. Geological Survey, Oca _ la, Florida. Figure 13 shows the location of all gaging points, and table 14 TABLE 14. Stream-flow measurements in the vicinity of Lake Parker and Saddle Creek (Measurements by U.S. Geological Survey, Ocala, Fla.) Station shown Flow (cfs) Flow (cfs} on figure 16 0-15-55 2-15-50 I..ake Parker: K (Inflow) 1.67 1.00 L (Inflow) .54 .22 :\I (Inflow) 4.63 .28 N (Outflow) 3.38 .00 Saddle Creek: A 9.90 14.00 B 45.20 8.22 C 15 . 30 3.00 J 116.00 14.00 lists the two sets of measurements made at these points. In September 1955 the lake was above the level of the outlet-control structure, total surface inflow was 6.84 cfs ( cubic feet per sec ond), and total outflow was 3.38 cfs. In February 1956, when the lake was below the level of the outlet-control, total surface inflow ! was 1.50 cfs and there was no surface outflow. Surface inflow prob ably exceeds surface outflow during most or all of the year. The inflow to the lake during the test period was estimated to be 8.1 in~hes over the lake surface; the outflow during the same period was estimated to be 3.3 inches. City storm sewers carry the drainage from approximately 1.7 square miles (1,100 acres) into Lake Parker, but probably not more than 25 percent of the total rainfall on this area reaches Lake Parker through the sewers. Thus, 1,100 acres X 17 inches X .25 72,200 acres= 2.1 inches of water contributed to Lake Parker from storm sewers. Lake Parker receives some overflow water from Lake Mirror through gravity-flow drains. Lake Mirror, in turn, receives over flow from Lake Wire. The amount of water added to Lake Parker from this source is unknown. Ground-water inflow to Lake Parker from the nonartesian aquifer can be computed by the use of Darcy's law, which can be written as Q = PIA, where Q is the flow in gallons per day; P is the coefficient of permeability; I is the hydraulic gradient in
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REPORT OF INVESTIGATION No. 44 149 feet per foot ; and A is the area in square feet of the cross section through which the flow is taking place. The average permeability of the sands sampled in the lake bottom (Stewart, 1963, table 9), 85 gpd per sq. ft., was used in making these computations. Hy draulic gradients were determined from figure 13, a map of the water table in the Lake Parker area. Saturated thicknesses of the nonartesian aquifer were taken from drilling and test data. The total ground-water inflow to Lake Parker was thus com puted to be 220,000 gpd. This amounts to approximately 0.7 inch of water over the lake surface from January through June 1956. The evaporation loss from the lake between January 1 and June 20, 1956, was estimated to be 23 inches. The approximate water budget may then be tabulated as follows: Gains: Rainfall Surface inflow Storm-sewer inflow Ground-water inflow Lake Mirror overflow Losses: Inches of water 17.0 8.1 2.1 .7 ? 27.9+ Evaporation 23.0 Surface-water outflow 3.3 Ground-water outflow in nonartesian aquifer 0.0 26.3 Difference (downward flow to aquifers) 1.6 The amount of the difference between gains and losses is well within the accuracy limits of some of the data used in computing it, and therefore has little significance. The budget appears to be essentially in balance. However, during this period, the lake actually declined about 14.5 inches (fig. 30). Other factors in the budget having been accounted for, this decline is due primarily to vertical seepage from Lake Parker into one or more of the underlying artesian aquifers. Figures 17 and 21 indicate that this leakage is probably going into the Floridan . aquifer rather lhan into the secondary artesian aquifer. This is shown by the bulge in the piezometric surface of the Floridan aquifer under the lake (fig. 21), and a trough in the piezometric surface under the lake
PAGE 159
150 FLORIDA GEOLOGICAL SURVEY is indicated for the secondary aquifer (fig. 17). Such a relation ship may be due to generally more permeable materials filling the erosional channels in the lake bottom, where the secondary aquifer is absent, than in the less disturbed or reworked mate rials overlying the secondary aquifer in the shore areas. It may be due in part to the greater hydraulic gradient existing in the filled channel sections than in the shore areas. The coefficient of permeability used in this budget is applicable to the sands of the nonartesian aquifer only. However, the sand in the lake bottom is known to be underlain, at least in part, by clays and sandy clays which observation indicates are probably of much lower permeability than the sands. The coefficient of vertical permeability of the materials overlying the Floridan aqui fer in the lake bottom may be approximated by transposition of the formula Q = PIA, to P == Q/IA. From the water budget above., Q == 2.5 inches/month == 0.051 gpd/ sq. ft. From figure 29, and the piezometric map of the Floridan aquifer in 1956 (fig. 21), the vertical hydraulic gradient, I, equals the difference in head of the lake and the aquifer divided by the distance between the lake bottom and the top of the aquifer, or I== 2 00 ft. The area through which the flow is taking place is 1 sq. ft. There fore-P == .051 gpd/sq. ft. + (23 ft. + 100 ft.) X 1 sq. ft. == .051 gpd/sq. ft. + 0.23 == 0.22 gpd / sq. ft. The coefficient derived here represents a summation of the thickness and permeabilities of all the materials which overlie the limestone aquifers in the lake bottom. Though it is recognized that leakage through the lake bottom may, or may not, be oc curring in only a small part of the lake, the coefficient derived here is useful in that it provides some knowledge of the order of magnitude of the permeabilities of the confining beds of the aqui fer and the lake bottom sediments. Other factors in the budget having been accounted for, the observed decline of the lake is due primarily to vertical seepage from the lake to the underlying Floridan aquifer. At other times, the lake receives more water than it is losing and as a result lake level rises. The fluctuations of the lake level, both long and short-term are the result of im balance between gains and losses of water. It is not known whether recharge to the artesian aquifer from
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REPORT OF INVESTIGATION No. 44 151 Lake Parker occurs over most of the lake bottom or in only certain areas. Chemical analysis of ground-water samples, however, shows that the mineral content of the water from both the Floridan and the secondary artesian aquifers is lowest near the north eastern arm of Lake Parker and Fish Lake, suggesting that the best connection between Lake Parker and the artesian aquifers ' is in that area. This is also supported by the hydrographs of figure 32, showing rapid response to recharge and discharge by all aquifers. The contours on figure 17 indicate that water may have been leaking from Lake Parker into the secondary artesian aquifer in June 1956 and moving laterally through the aquifer to discharge at spring E, near Saddle Creek. In December 1954, water was pumped at a rate of 7,500 gpm from an active mine pit in the secondary artesian aquifer, 0.3 mile south of spring E (fig. 17). Such withdrawals were made in the general vicinity of springs E, F, and G from late in 1953 until late in 1957. These prolonged withdrawals do not appear to have affected the level of Lake Parker substantially. If any such leakage into the secondary ar tesian aquifer occurred, it was a very small amount. The observed decline of the lake level during 1954-1956 is largely due to below normal rainfall, continued downward leakage, reduced inflo"\\'.", and increased evaporation. The decline of Lake Parker is consistent with, but less than, the decline of other lakes in the vicinity that are farther from the mining area. CONCLUSIONS The future withdrawal of ground water from mine pits in the nonartesian aquifer in the area south of State Highway 33 and north and northeast of Lake Parker may tend to lower the level of the lake in these ways: (1) It will reduce the ground-water inflow into the lake by interception, and (2) it might induce ground-water outflow from the lake through the nonartesian aqui fer toward areas where the water table is drawn down to especi ally low levels near the shore. (3) Withdrawal of water for mining from the artesian aquifers also will lower the piezometric surface and increase the vertical hydraulic gradient under the lake, thus increasing the rate of leakage from the lake to the aquifer. If mining takes place in the lake itself, seyere lowering of the lake level by increased downward leakage could occur. Wit}1out consideration of possible remedial measures, the leakage could
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152 FLORIDA GEOLOGICAL SURVEY be increased in the following ways, in addition to the three ways listed above : (1) Such mining would probably proceed by segmenting the areas to be mined by construction of earth dams and then pumping the segments dry. Such pumping and subsequent removal of the lake bottom sands and underlying leached zone and matrix would create a substantial hydraulic gradient on opposite sides of the dams. This would induce leakage from the lake by underflow through the permeable sand bottom under the dam and into the pit. (See fig. 29.) Under existing conditions this could be sev eral millions of gallons per day in a pit 1,000 feet long -and an average sand thickness of 20 feet. Given sufficient flow in this situation, it is possible that the sand would erode rapidly from under the dam into the pit. Such an occurrence would permit sudden entry of large quantities of lake water into the pit. (2) In such pits, or in mined-out pits which were reconnected to the lake, the rate of downward leakage would be greatly in creased due to the increase in vertical hydraulic gradient result ing from the reduction in thickness of the confining beds of the artesian aquifers in the pit floors. (3) If cavernous conditions exist near the top of the lime stones underlying the lake, as they are known from other nearby : mining areas (See fig. 10.), then mining might foster the col lapse of cavern roofs, or might accidentaily breach such a cavern, and permit the draining of even larger amounts of water than indicated in (1) and (2) above. (4) Mining would lower the pit bottoms well below the piezo metric surf ace in some areas of the lake, and again significantly reduce the thickness of the confining beds overlying the lime stones. This might lead to rupture of the reduced confining bed by blow-out due to artesian pressure, and in this way provide direct access of lake water to the limestones which would be as effective as cavern collapse. ( 5) The dams necessary for mining, if extended entirely across the northern arms of the lake, would intercept a significant part 'Of the surface-water inflow to the lake. Though this may amount to only 3 to 12 inches of water per year over the la;Ice surf ace, the water budget would thus be unbalanced even further than at present, and the lake level affected accordingly. These comments all strongly indicate the necessity of detailed engineering studies prior to the undertaking of mining operations in the lake.
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REPORT OF INVESTIGATION NO. 44 153 SCOTT LAKE HISTORY AND NATURE OF THE PROBLEM Early in 1953 the Board of County Commissioners of Polk County requested that the U.S. Geological Survey investigate the water problems in the Scott Lake area, south of Lakeland. Property owners were concerned about the obs.erved decline of lake level because of the lake's recreational value and its value as a source of water for the irrigation of adjacent citrus groves. In 1953 a staff gage was installed on a boat dock on the south east shore of the lake. Later a recording gage was installed at the same place, and wells were inventoried in the lake basin. Re cording gages were installed on an abandoned well in the second ary artesian aquifer (757-155-3) near the ridge crest, southeast of the lake, and on a well in the nonartesian aquifer (758-156-5) on the north shore of the lake. (See fig. 4.) Both the secondary artesian and Floridan aquifers are present in the ridge section around Scott Lake and both aquifers are in use, but wells into the Floridan aquifer are much more numerous. Because of the pump installations, very few of the wells around the lake shore can be used for water-level measurements. Ob served and reported water levels indicate, however, that the water level in the Floridan aquifer may be as much as 80 feet below that of the secondary artesian aquifer on the basin floor, and it is approximately 20 feet below that of the secondary artesian aqui fer on the ridge top east of Scott Lake. Figures 33 and 34 show the hydrographs of Scott Lake and wells in the Scott Lake area. The hydrographs of wells shown in figure 34 are arranged with the topographically highest well at the top of the figure and the lowest at the bottom. The locations of wells in the Floridan, nonartesian, and secondary artesian aquifers, in the vicinity of Scott Lake, are shown on figures 35 and 36. Figure 33 shows that the hydrographs of Scott Lake and well 758-156-5 intersect, indicating periods of reversal in the direction of ground-water flow in the nonartesian aquifer in one part of the shore area. Figure 34 shows that the water level in well 758-156-1 in the same general part of the shore area also fluctuates above and below the level of Scott Lake. In that part of the shore area during periods of normal rainfall, recharge to the nonartesian aquifer is sufficient to maintain a hydraulic gradient from the drainage divide downward to the lake, indicating discharge from the aquifer into the lake. As in much of Polk County, a down
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154 FLORIDA GEOLOGICAL SURVEY 110 1681 ~-.,.-166 '. 164 ; Well 758-156-5, Smile~ S. of Lokelond 162 . +------------:; . (Nonorlesi011 aquifer) ;16Q,I.-.-------'------------------------------:--~ 0 .. .. 118,---------~---~----.-----.----r----, " 0 .. 116 E 114 { Secondary o,tesion oqu,lerl _g 112~ , o I Weil 757-155-3 , 6 mtles SE. _ o , ' Lokelond 110 .:!. "1oa 1106 .!! ii ,04. 0 I 102: I ' 100! ! 98 ; 961 ! . ,. . . . .. . Well 757-155-6, 6 miles SE. ol Lokelond 92---: -----90-94 '. 84' ----------; L.. -------------------"'---------------' i 954 1955 1956 1957 1958 1959 1960 Figure 33. Hydrographs of water levels in Scott Lake and in wells 758156-5, 757-155-3, and 757-155-6, 1954-1960. ward hydraulic gradient also exists between the water table and the piezometric surfaces of the underlying artesian aquifers, and water is being lost from the nonartesian aquifer to the artesian aquifers. The water table .fluctuates slightly with day-to-day rainfall. The rate of decline of the water table is dependent on rainfall, recharge to the limestones, and discharge to the lake. During extended periods of below-normal rainfall, the water table in the area of the two wells is lowered rapidly by ground water inflow to the lake from the aquifer. Eventually the hy draulic gradient on the lake basin floor becomes very flat, and ground-water inflow to the lake is reduced to a very small amount. During periods of low evaporation the water table declines in a direct relationship with lake level, although the quantities of water lost are not greatly different. The decline is at a ratio of I,
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REPORT OF INVESTIGATION No~ 44 155 199,.......,-,.......,,.......,,.......,,--,-,--,-,-,-,-,-,--,.--,.---,----,----,----,----,----,----,----,----,----,---,---,---,..--,.._ l881---------r1---------~--------+--------1 Well 757-157-3 1971-------+-------mile southwest of Scott Lake 186._ __ ---,__ Depth of well 20 ft ---------+----~ d t84 > w Depth of casing 20ft. -' 183 1 -----,,------'-...-t-----, 4 w (/) 182._ __ " z 4 18(1---------------+-----'""'-=_..L-.------+---~---i w 180'-----'---'---'---'---'---'--''-''-'---'---'---'---'---'----'----'---'---'--'----'----'----'----'------'------'--'---'---"' CD 4 t174~-~---.---------------------.---.--.--,---,---,---,---,---.---,.--, Well 758-157-4 lL 173--------d'-_.,,_mile northwest ______________ __, z of Scott Lake d 1121----------~~_u,epth of well 42 ft. -----+-------i > Depth of casing w ..J 1711-----""-...::--l---~-----t----",------,"'----=-t,.,;;;::-------i a:: w 170 1691---,...,._----r-.-------1t----........_, near southwest shore ..,._,_ __ ,-i of Scott Lake Depth of well 17 ft. 168 1---'-------+W-1-e-ll7 5 9 -_15 6 -_"""' 1 1c------Depth of casing 15 ft.(?) 1671--------mile northwest Scott Lake 166._ _____ Depth of well 30 ft . ---~,__-----+--~.--------1 Depth of casing unknown 165~-----------1-----------+-----""'-,;I 164 J F M A M J J A S 0 N D J F M A M J J A S 0 N D J F M A M J . 1954 1955 1956 . . Figure 34. Hydrographs of water levels in wells in the nonartesian aquifer in the Scott Lake area.
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156 F'LoRIDA GEOLOGICAL SURVEY 28 8t'58 59 37 A Sinkhole rim 8-0an C-LOlle drain 08-A.ine pits 57' 56' EXPLANATION 5 163 . Well penetrating nonartesian aquifer i. 101 Well penetrating secondary artesian 0 L 157 Well penetrating Floridan aquifer @) ..L 81 Well penetrating solution cavity aquifer a_ 88 81 1 2a 0 00' 59' 0 5,Tt----------+-f~------'~;:+!.--.::::"0 1 -"-7!\~~---l:1-----t s1' V4 1/2 3/4 mile jlii.=====5:e::::=E=::::i:!!:5!:!c:===:::::i 27o,-----------.u-------...... ---------21•ss' m-59• 57' 56' 81' Figure 35. Map showing water levels and other features of the Scott Lake Lake area, July 1956.
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REPORT OF INVESTIGATION No. 44 157 a1se' 57' ss' . a1ss' 2s"OO',--------rr----..,-,r----------r-----------.2e•oo' 37 90 0 •..1. 7 138 I 900 59•---------------EXPLANATION 2 160• Well penetr.oting secondary artesian aquifer 3 0 93 Well penetrating Floridan aquifer Upper number is well number on r.gure q , Lower number is ollilude of woler level , in feet above mean sea level; shown with e where estimated. 0 I 89 3 89 \. 113 " 2 0 94 5 /. 89oe/.ll.3 6 90 57 1 1------------------1/q I mile ~!!!!!!!!I.ii-!!!!!!!!!!!!!!!~-II 2 () 87 59' . .1ss•..,_ _________ ......_ _________ __._ __________ 21ss' 81' 57' 56' 81' Figure 36 . . M~p showing water levels and other features of the Scott Lake area, October 1959-February 1960.
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158 FLORIDA GEOLOGICAL SURVEY about 3 : 1, which reflects the porosity of the aquifer (Stewart, 1963, table 9). During periods of high evaporation the decline of the water table and lake level are more nearly equal, because the lake is then losing greater quantities of water than the water table. The data from the nonartesian aquifer are sparse in the rest of the lake basin, but it is believed that ground-water levels are always above the lake level in most of the basin. Figure 33 shows the hydrographs of well 757-155-3, in the secondary artesian aquifer, and that of Scott Lake. The major drawdowns in the well in the spring months are caused by local heavy pumping from multi-aquifer irrigation wells. An irrigation well 50 feet away from 757-155-3 is open only to the Floridan aquifer and is in daily use for domestic purposes, but pumping of this well has not affected the water level in well 757-155-3. WATER BUDGET In order to evaluate the factors involved in the decline of Scott Lake, it is necessary to establish a water budget for the basin. The period January 1 through June 30, 1956, was used to compute the budget for Scott Lake. Surface outflow from the lake may occur through a water gap ' in the sinkhole rim point A that opens westward from the northwest bulge of the shoreline. The swampy channel occupying the gap> called the "Lake Drain," is shown on figure 35. Phosphate mining operations have interrupted the natural flow through the Lake Drain at point C. Water may not flow through a canal on the north side of mine pit D only when the lake level is above an altitude of 168 feet. At point B, figure 35, a small earthen dam prevents westward flow from the lake when the lake level is less than 168 feet above msl. Thus, water will not flow out through the Lake Drain if the lake level is less than 168 feet above msl. The maximum lake level during the budget period was 157 feet above msl and no outflow occurred. A concrete control structure has been built in the channel, on the lakeward side of the high way crossing the Lake Drain. The top of this dam is also 168 feet above msl, and the bottom of the control weir is 166 feet above msl. When the lake level is low, generally less than 166 feet above msl, water is permitted to flow from an abandoned mine pit (point E, fig. 35). Such was the case during the last half of the budget period. This observed inflow, though not measured, is be
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REPORT OF INVESTIGATION No. 44 159 lieved to have been much less than one cubic foot per second. For budgetary purposes, therefore, surf ace inflow is established, but quantitatively unknown. Surface inflow also occurs intermit. tently into the lake at its southwest arm, as shown on figure 35. In the following computations the average coefficient of per meability for the nonartesian aquifer of 85 gpd per sq. ft. is taken from Stewart (1963, table 9). The lake basin was divided into segments and the ground-water inflow was computed for each segment. Hydr.ulic gradients were approximated from data from the observation wells shown in figure 35. On the basis of avail able well data, the average saturated thickness of the aquifer around the shoreline is believed to be 25 feet, and possibly more. Ground-water inflow was computed to be eqiuvalent to approxi mately 17 inches over the lake surf ace from January 1 through June 30, 1956 (780,000 gpd). It is assumed that there is no lateral ground-water outflow from the Scott Lake basin in the nonartesian aquifer. Rainfall at the Lakeland station was approximately 17 inches from January 1 through June 30, 1956. Evaporation was estimated to be 23 inches. The lake level is lowered by pumping for citrus irrigation, as well as by evaporation. Pump capacities and the duration of pump ing periods reported by owners of the irrigation systems indicate that the total seasonal punipage from the lake is approximately 38 million gallons. Such withdrawals are usually made from January through April. The area of the lake surface is about 300 acres. According to these figures, average irrigation pumping would amount to about 4.5 inches over the lake surf ace per season. The water budget for Scott Lake may be summarized for the period January 1 through June 30, 1956 as follows. Gains: Rainfall Surface inflow Ground-water inflow Losses: Evaporation Surface outflow Irrigation pumping Total Ground~water outflow in nonartesian aquifer Total ] >iff erence ( downward flow to artesian aquifer) Inches of water 17 -+ 17 34+ 23 0 4 0 27 7+
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160 FLORIDA GEOLOGICAL SURVEY These figures indicate a small surplus for the 6-month per10c, however, figure 33 shows that the lake level actually declined 2 inches during the same period. The lake was recharging one or more of the underlying artesian aquifers, through the lake bottom, during this period and the recharge was equivalent to about 31 inches (24-inch loss plus 7-inch c_alculated surplus) over the lake surface. Figures 19, 35, and 36 show a high on the piezometric surface of the secondary artesian aquifer adjacent to the lake and a slope of this surface away from the lake, indicating recharge of the aquifer by the lake. Observed and reported ground-water levels and figure 23, however, show that the piezometric surface of the Floridan aquifer is low under Scott Lake, indicating discharge from that aquifer. If some recharge to the Floridan aquifer occurs from Scott Lake, it is not enough to prevent the piezometric sur face of the aquifer from remaining at a low level in the vicinity of the lake. The coefficient of permeability used in this water budget is applicable only to the nonartesian aquifer. Drilling data indicate that this aquifer is underlain by more clayey and less permeable materials at depth in the filled sinkhole lake basin. The general ized coefficient of permeability for the fill materials in the filled sink under the lake bottom may be determined by transposition of the formula Q == PIA, to P == Q/IA. The vertical hydraulic gradient, I, is the difference in head between the land and the sec ondary artesian aquifer, divided by the distance between the lake bottom and the top of the aquifer. In well 757-156-2 this distance is 49 feet. From the water budget, Q is 5 inches of water per month, or 0.103 gpd-/sq. ft. The area, A is 1 sq. ft. Therefore: P == 0.103 gpd/sq. ft.+ (8. ft.+ 49 ft.) X 1 sq. ft. == 0.103 gpd/sq. ft. ""7" 0.153 == .631 gpd/sq. ft. which is substantially lower than that of the nonartesian aquifer. ! The coefficient derived here is a summation of the thickness_. and permeabilities of all the materials through which the water leaking from the lake to the aquifer must pass. It may net represent any single one of these accurately, and the materials underlying the lake bottom may not be uniform, hence rate of recharge may differ considerably over the lake basin.
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REPORT OF INVESTIGATION No. 44 161 CONCLUSIONS The level of Scott Lake is lowered only 4.5 inches by irriga tion pumping from the lake in an average irrigation season if all the pgmping stations available in 1959 were used simultaneously. This is approximately equal to one :month's evaporation from the lake surface. The lake is leaking and furnishing appreciable quantities of recharge to the secondary artesian aquifer, as are parts of the lake basin slope. Figure 19 indicates a piezometric high at the southwest side of the lake. A similar high on the east side of the lake may be prevented by discharge through the aquifer eastward towards Lake Hancock. This discharge is indicated by the re entrants in the piezometic contours between the two lakes. Some of the leakage from Scott Lake may be going into the Floridan aquifer, but this has not been definitely established. The investigation has shown that the fluctuations of Scott Lake are due to entirely natural conditions ( except for minor irrigation use), and. that these fluctuations reflect the sum of all : the factors of the water budget of the lake. A reduction of pres . sure in the secondary artesian aqgifer, by discharge from wells in the vicinity of the lake, will increase the vertical hydraulic gradient between the lake and the aquifer and thereby increase the rate of leakage. At other times, generally during the fall and winter months, the lake receives much more water than is being lost and as a result the lake level rises (fig. 33). SUMMARY Polk County approximately in the center of peninsular Florida comprises an area of about 1861 square miles. It is part of the central highland area that trends along the longitdinal axis of the peninsula. Three long irregular ridges are major topographic features in the county on which are located the centers of popula tion. The well-drained ridges and inter-ridge areas are extensively used for citrus groves. Most of the area of the county is broad, r oorly drained lowlands which is devoted to cattle ranching and rhosphate mining. Total relief in the county is 255 feet (50 to E05 feet above msl). Surface drainage is poorly developed in the county. Sinkhole basins of subsurface drainage are n~merous and nany of them contain lakes. Surficial sands are underlain by phosphatic clays _ and marls
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162 FLORIDA GEOLOGICAL SURVEY which range in age from Miocene to Recent. These are underlain by porous limestones which range in age from middle Eocene 1 o Miocene. Though covered by the overlying sands and clays, the area is a buried limestone terrane. The formations dip, and thicken, southward from a structural high located in the northern part of the county. This high is the southern end of the Ocala, Uplift. A previously unmapped area of rock outcrop in northwestern Polk and adjacent counties has been mapped and described. The out crop area contains silicified remnants of the contact zone between the Oligocene Suwannee Limestone and Eocene Crystal River Formation. Previous workers dated the Ocala uplift as late Oligocene or early Miocene, and have postulated that the rocks of the area respond to structural deformation by fracturing, rather than by bending or warping. This investigation shows that a structural high existed in this area since the deposition of the Avon Park Limestone (middle Eocene). Considerable erosion occurred after the deposition of each of the formations in the area except the Inglis and Williston Formations of the Ocala Group. These erosional intervals were probably accompanied by repeated up lift of the structural high. Structural studies indicate that the rocks were probably faulted as a result of the uplift. Vertical displacement along the faults generally ranges from 10 to 5 0 feet, ,vith a few local displacements up to 300 feet or more. Fault ing probably continued at least through the Miocene. Ground water in Polk County occurs under both nonartesian and artesian conditions. The water table is close to land surface in lowland areas, but may be 70 feet or more below land surface in the ridge area. The nonartesian aquifer consists of undiffer entiated elastic deposits which may range in age from Miocene to Recent. The thickness of this aquifer generally ranges from 1 to 250 feet, and where it is more than 10 feet thick it will generally furnish sufficient water to supply small domestic and irrigation requirements. Although the aquifer is not extensively used, the water is fresh and generally acidic. Locally, it may be highly: mineralized due to commercial fertilizers used in agriculture or by other types of pollution. The uppermost artesian aquifer occurs in the lower part d the undifferentiated elastic deposits underlying the nonartesian aquifer. The clay contains pebble-phosphate which is mined extensively in the south:western part of the county. The . deposi1s may range in age from Miocene to Pleistocene. The thickness and
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REPORT OF INVESTIGATION No. 44 163 a teal extent of this aquifer is unknown. It is not extensively used. The secondary artesian aquifer is composed of the limestone units of the Hawthorn Formation of Miocene age. The aquifer is generally present over the southern three-fourths of the county and is used more than either of the two overlying aquifers. The principal use is for domestic supply, but in the Lakeland area it is also important as a source for irrigation supplies. The lime stone is clayey and the permeability is generally low. However, the existence of caverns developed along fractures greatly increases the productivity of the aquifer and locally, such features are large enough to supply large-diameter irrigation wells. Water from the aquifer is fresh and moderately hard. The Floridan aquifer is the principal source of water in the county. The aquifer is of vast areal extent, underlying all of Florida and parts of adjacent states. In Polk County it is composed I of a thick section of limestones that range in age from middle ! Eocene to Oligocene and function as a single aquifer. The presence Df anhydrite and gypsum in the lower few feet of the Avon Park Limestone and in the underlying Lake City Limestone in the Lakeland area indicates that the Avon Park is the basal unit of the aquifer in that area and probably the remainder of the county as well. Considerable horizontal flow occurs within the cavern systems in the aquifer. The flow is sufficient to cause linear dra":7down in the aquifer along the course of the caverns which appear as troughs in the piezometric surf ace. The aquifer is under artesian conditions except for a small area along the crest of the northern part of the Lake Wales ridge, where evidence indicates that it may be under nonartesian conditions. Water wells drilled into the Floridan aquifer range from 2 to 30 inches in diameter and from 10 to 1,400 feet in depth. The largest known yield from a well in this aquifer was 8,000 gpmt with 23 feet of drawdown, from a 24-inch well, 1,200 feet deep. vVater in the aquifer is fresh and moderately hard. Well yield is : Primarily controlled by penetration of solutional features. ' The two principal industries in the area-the growing and P l' ocessing of citrus fruits and the mining and processing of P ~hble-phosphate-use large quantities of ground water. The g owth of population has greatly increased municipal and domes 't: ~ consumption in recent years. During 1959 ground-water pump , 1a . {e from all sources in the county was estimated to be _ approxi n ately 80 billion gallons.
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164 FLORIDA GEOLOGICAL SURVEY Polk County overlies the highest point on the piezometr ~ c surface of the Floridan aquifer in peninsular Florida. It has long been thought that Polk County, therefore, represented a principal recharge area for the aquifer, and that most of this re charge was supplied by downward leakage from the numerous sinkhole lakes of the area. Investigation of the Lakeland area, however, has shown that although some recharge niay come from these Jakes, the amount may be small; most of the downward leakage from some of these lakes is recharging the secondary artesian aquifer rather than the Floridan aquifer. Many of the sinkhole lakes overlie troughs in the piezometric surface, there fore., leakage to the aquifer is not sufficient to cause doming of the piezometric surface. The present investigation shows that the Floridan aquifer is recharged, m~inly by the slow downward percolation of water through the confining beds over most of the county. The total recharge to the aquifer is estimated to be only a few inches of water per year (approximately 120 billion gal lons) which is substantially less than the amounts lost to evapo transpiration or to surface runoff. Lake Parker, in eastern Lakeland, also recharges the artesian aquifers at a slow rate. Large withdrawal of ground water is anticipated in the area along the north shore of the lake, and ~t may lower the lake level by reducing the ground water discharged into the lake; it may even establish hydraulic gradients away from the lake, thereby increasing losses through the lake bottom . It appears, however, that similar large withdrawal east of the lake did not affect the lake level. Scott Lake, a sinkhole lake south of Lakeland, recharges the secondary artesian aquifer. The effect of withdrawal from the lake for irrigation of citrus groves is equivalent to lowering the lake level approximately 4.5 inches per season, but the principal reasons for large seasonal declines of the lake level are : ( 1) con tinuing downward leakage to the secondary artesian aquifer, (2) evaporation from the lake surface, and (3) below-normal rain fall, which has caused the water table to decline and has reduced the ground-water discharge into the lake.
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J.ltschuler, Z. S. REPORT OF INVESTIGATION No. 44 REFERENCES 165 1956 (and Jaffe, E. B., and Cuttitta, Frank) The aluminum phos phate zone of the Bone Valley Formation, Florida, and its ura nium deposits: U.S. Geol. Survey Prof. Paper 300, p. 495-504. 1958 (and Clarke, R. S., Jr., and Young, E. J.) Geochemistry of uranium in apatite and phosphorite: U.S. Geol. Survey Prof. Paper 314-D. 1960 (and Young, E. J.) Residual origin of the "Pleistocene" sand mantle in central Florida uplands and its bearing on marine ter races and Cenozoic uvlift: U.S. Geol. Survey Prof. Paper 400-B, p. 202-207. Alverson, D. C. (see Carr, W. J.) Anders, R. B. (see Peek, H. M.) Applin, E. R. (also see Applin, Paul L.) 1945 (and Jordan, Louise) Diagnostic foraminifera from subsurface formations in Florida: Jour. Paleontology, v. 19, no. 2, p. 129-148, pls. 18-21, 2 test figs. Applin, Paul L. 1944 (and Applin, E. R.) Regional subsurface stratigra.phy and struc ture of Florida and southern Georgia: Am. Assoc. Petrole1:1:m Geologists Bull., v. 28, no. 12, p. 1673-1753. Baker, D. R. (see Kohler, M.A.) Bergendahl, M. H. 1956 Stratigraphy of parts of DeSoto and Hardee Counties, Florida: U.S. GeoL Survey Bull. 1030-B. Berm es, B. J. 1958 Interim report on geology and ground-water resources of Indian River County, Florida: Florida Geol. Survey Inf. Circ. 18. Bishop, Ernest W. 1956 Geology and ground-water resources of Highlands County, Flor ida: Florida Geol. Survey Rept. Inv. 15. Black, A. P. 1951 (and Brown, Eugene) Chemical character of Florida's waters: Florida State Bd. Conse1v., Div. Water Survey and Research,. Paper 6. f.lade, L. U. (see Cathcart, J. B.) Flaney, Harry F. 1956 Comments on Estimating Evaporation, by H. L. Penman= Am. Geophys. Union Trans., v. 37, no. 1, p. 46-48. Lown, Eugene (see Black, A. P.; Cooper, H. H., Jr.)
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166 FLORIDA GEOLOGICAL SURVEY Carr, W. J. 1953 (and Alverson, D. C.) Stratigraphy of Suwannee, Tampa anil Hawthorn formations in Hillsborough, and parts of adiacent count-ies, Florida, in Geologic Investigations of rad:ioactive de posits semiannual progress rept., June 1, 1953 to Nov. 30, 1953: 1959 U.S. Geol. Survey TEl-390, issued by U.S. Atomic Energy Comm. Tech. Inf. Service, Oak Ridge, Tenn., p. 175-185. Strat-igraphy of middle tertiary rocks in part of west-central Florida: U.S. Geol. Survey Bull. 1092. Cathcart, J. B. 1952 (and Davidson, D. F.) Distribution and origin of phosphate in the land-pebble phosphate district of Florida: U.S. Geol_. Survey TEI-212, issued by U.S. Atomic Energy Comm. Tech. Inf. Serv ice, Oak Ridge, Tenn. 1953 (and Blade, L. U.; Davidson, D. F.; and Ketner, K. B.) Geology of the Florida land-pebble phosphorite deposits: Internat. Geol. Cong., 19th, Algiers, 1952, Comptes rendus, sec. 11, pt. 11, p. 77-91. 1959 (and McGreevy, L. J.) Results of geologic exploration by core drilli-ng, 1953, land-pebble phosphate district Florida: U.S. Geo!. Survey Bull. 1046-K. Cherry, R. N. (see Pride, R. W.) Clarke, R. S., Jr. (see Altschuler, Z. S.) Cole, W. Storrs 19-11 Stratigraphic and paleontologic studies of wells in Florida: Florida Geol. Survey Bull. 19. 19-15 Stratigraphic and paleontologic studies of wells in Florida No. 4: Florida Geol. Survey Bull. 28. Collins. \V. D. 1925 Te-mpcraturc of water a1Jailable for industrial use in the United States: U.S. Geol. Survey Water-Supply Paper 520-F. 1928 (and Howard, C. S.) Che1nical character of waters of Florida: U.S. Geol. Survey Water-Supply Paper 596-G. Cooper. H. II., Jr. (also see Stringfield, V. T.) 1944 Ground-water investigations in Florida (with special reference , to Duval and Nassau Counties): Am. Water Works Assoc. Jour., v. 36, no. 2, p. 169-185. 1953 (and Kenner, W. E., and Brown, Eugene) Ground water in cen tral and northern Florida: Florida Geol. Survey Rept. Inv. 1(1. Cooke, C. \V. 1939 Scenery of Florida, interpreted by a geologist: Florida Geo;. Survey Bull. 17. 19-15 Geology of Florida: Florida Geol. Survey Bull. 29. Cuttitta, Frank (see Altschuler, Z. S.)
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REPORT OF INVESTIGATION No. 44 167 Davidson, D. F. (also see Cathcart, J.B., 1952, 1953) 1952a Relation of the "topography" of the Hawthorn Fo1mation to size of phosphate particles in the deposits, and to topography, in the northern part of the land-pebble phosphate field, Florida: U.S. Geol. Survey TEM-337, issued by U.S. Atomic Energy Comm. Tech. Inf. Service, Oak Ridge, Tenri. 1952b G1ain size distribution in the sU'rf ace sands and the economic phosphate deposits of the land-pebble phosphate district, Florida: U.S. Geol. Survey TEM-362, issued by U.S. Atomic Energy Comm. Tech. Inf. Service, Oak Ridge, Tenn. Espenshade, G. H. 1963 (and Spencer, C. W.) Geology of phosphate deposits of northern peninsular Florida: U.S. Geol. Survey Bull. 1118. Fenneman, N. M. 1938 Physiography of the eastern United States: New York; McGraw Hill Book Co. Ferguson, G. E. (also see Parker, C. G.) 1947 (and Lingham, C. W.; Love, S. K.; and Vernon, R. 0.) Springs of Florida: Florida Geol. Survey Bull. 31. Follansbee, Robert 1934 Evaporation f'lom reservofr surfaces: Am. Soc. Civil Engineers Trans., v. 60, p. 704-747. Gunter, Herman (also see Sellards, E. H.) 1931 (and Ponton, G. M.) The need /01 conservation and protection of our water supply with special reference to waters from the Ocala Limestone: Florida Geol.. Survey 21-22d Ann. Rept., p. 43-58. Heath, Richard C. 1961 Surface-water resources of Polk County, Florida: Florida Geol. Survey Inf. Circ. 25. Hetherington, M. F. 1928 History of Polk County, Florida: The Record Company, St. Au gustine, Florida. Horton, Robert E. 1943 Evaporation maps of the United States: Am. Geophys. Union Trans., pt. II, p. 743-753. Howard, C. S. (see Collins, W. D.) Jaffe, E. B. (see Altschuler, Z. S.) Jordan, Louise (see Applin, E. R.) Kenner, W. E. (see Cooper, H. H. Jr.) ;:etner, K. B. (also see Cathcart, J. B.) 1959 (and McGreevy, L. J.) Stratinrapky of tke area between Her nando and Hardee Counties, Florida: U.S. Geol. Survey Bull. 1074-C.
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168 .FLORIDA GEOLOGICAL SURVEY Klein. Howard 1954 Ground-water resources of the Naples area, Collier County, Flor ida: Florida Geol. Survey Rept. Inv. 11. Kohler, M. A. 1959 (and Nordenson, T. J., and Baker, D. R.) Evaporation maps for the United States: U.S. Weather Bureau Tech. Paper 37. Koo, Robert C. J. 1953 A study of soil moisture in relation to absorption and transpira tion by citrus: Univ. of Florida, Doctoral dissertation, Gaines ville, June. Lingham, C. W. (see Ferguson, G. E.) Love, S. K. (see Ferguson, G. E.; Parker, C. G.) McGreevy, L. J. (see Cathcart, J.B.; Ketner, K. B.) MacNeil, F. Sterns 1950 Pleistocene shorelines in Florida and Georgia: U.S. Geo!. Survey Prof. Paper 221-F. Mansfield, George R. 1942 Phosphate resources of Florida: U.S. Geol. Survey Bull. 934 •. Matson, G. C. 1913 (and Sanford, Samuel) Geology and ground waters of Florida: U.S. Geol. Survey Water-Supply Paper 319. Meinzer. 0. E. 1923a The occurrence of ground water in the United States, with a discussion of principles: U.S. Geol. Survey Water-Supply Paper 489. 1923b Outline of ground-water hydrology with definitions: U.S. Geol. Survey Water-Supply Paper 494. Menke, C. G. 1961 (and Meredith, E. W., and Wetterhall, W. S.) Water resources of Hillsborough County, Florida: Florida Geol. Survey Rept. Inv. 25. Meredith, E.W. (see Menke, C. G.) Meyer, A. F. (also see Pride, R. W.) 1942 Evaporation from lakes and reservoirs: Minnesota Resources Comm., St. Paul, Minn. Nordenson, T. J. (see Kohler, M.A.) Parker, C. G. 1955 (and Ferguson, G. E.; Love, S. K.; and others) Water resources of southeastern Florida: U.S. Geol. Survey Water-Supply Paper 1255. Peek, H.M. 1951 Cessations of flow of Kissengen Spring in folk, County, Florida: Florida Geo). Survey Rept. Inv. 7, pt. III.
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REPORT oF INVESTIGATION No. 44 169 1955 (and Anders, R. B.) Interim report on the ground water resources of Manatee County, Florida: Florida Geol. Survey Inf. Circ. 6. 1958 Ground-water resources of Manatee County, Florida: Florida Geo!. Survey Rept. Inv. 18. 1959 The artesian water of the Ruskin, area of Hillsborough County, Florida: Florida Geol. Survey Rept. Inv. 21. Perman, H. L. 1956 Estimating Evaporation: Am. Geophys. Union Trans., v. 37, no. 1, p. 4~-46. Pettijohn, F. J. 1949 Sedimentary Rocks: New York; Harper & Brothers. Pirkle, E. C. 1957 The Hawthorn and Alachua Formations of Alachua County, Florida: A paper presented at the First Ann. Meeting of Soc. Mining Engrs. of AIME, and S. E. States Mining Conferences, Tampa, Fla., Oct. 15-18. Ponton, G. M. (see Gunter, Herman). Pride, R. W. 1961 1964 (and Meyer, F. W.~ and Cherry, R. N.) Interim report on the hydrologic features of the Green Swamp area in Central Florida: Florida Geol. Survey Inf. Circ. 26 . (and Meyer, F. W., and Cherry, R. N.) Hydrology . of the Green Swamp mea in central . Flo'rida: Florida Geol. . Survey Rept. of Inv. 42. Puri, Harbans S. 1953a Zonation of the Ocala Group in peninsular Florida (abs.): Jour. Sed. Petrology, v. 23, p. 130. 1953b Contributions to the study of the Miocene of the Florida pan handle: Florida Geo!. Survey Bull. 36. 1957 Stratigraphy and zonation of the Ocala Group: Florida Geo]. Survey Bull. 38. Reitz, H.J. (see Wander, I. W.) Sanford, Samuel (see Matson, G. C.) Sellards, E. H. 1908 A preliminary report on the underground water supply of cen tral Florida: Florida Geol. Survey Bull. 1. 1913 (and Gunter, Herman) The artesian water supply of eastern. and southern Florida: Florida Geol. Survey 5th Ann. Rept., p. 105-290. S pencer, C. W. (see Espenshade, G. H.) :; tewart, H. G., Jr. 1959 Interim report on the geology . and groundwater resources of northwestern Polk County, Florida: Florida : Geol. Survey Inf. Circ. 28.
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170 FLORIDA GEOLOGICAL SURVEY 1963 Reconls of wells and other water-resources data in Polk County, Florida: Florida Geol. Survey Inf. Circ. 38. Stringfield, V. T. 1935 The piezometric surface of artesian water in the Florida Penin sula: Am. Geophys. Univ. Trans., p. 524-529. 1936 Artesian water in the Florida peninsula: U.S. Geol. Survey Wa ter-Supply Paper 773-C. 1951a (and Cooper, H. H., Jr.) Economic aspects of ground water in Florida: Mining Eng., June, p. 525-533. 1951b Geologic ancl hydro logic f ea tu res of an artesian submarine spring east of Florida: Florida Geol. Survey Rept. Inv. 7, pt. 2. Unklesbay, A. G. 19-U Ground-water conditions 1n Orlando and vicinity, Florida: Flor ida Geol. Survey Rept. Inv. 5. U.S. Bureau of Census 1957 1954 Census of Agriculture,• Counties and state economic areas -Florida: v. 1, pt. 18. U.S. Bureau of Mines 19:'i9 .Minerals yearbook, v. 3, Area Repts., table 5, p. 266. Vernon, R. 0. (also see Ferguson, G. E.) H)51 Geology of Citrus and Levy Counties, Florida: Florida Geol. Survey Bull. 33. lander, I. w. 1951 (and Reitz, H. J.) The chemical composition of irrigation watc1 U!~ecl in Florida c-itrus groves: University of Florida Agr. Exper. Sta. Bull. 480. '\Varren, .M. A. l!) .. 14 Artesian water in southeastern Georgia with special reference to the coastal area: Georgia Geol. Survey Bull. 49. '\Venzel, L.K. 19-!2 illcthods for determining permeability of water-bearing 1na.tcri als, with special reference to discharging-well methods: U. S. Geol. Survey Water-Supply Paper 887. '\Vetterhall, '\V. S. (see Menke, C. G.) 'White, William A. 1958 Some geomorphic features of central peninsular Florida: Florida Geol. Survey Bull. 41. \Vyrick, Granville G. 1960 The ground-water resources of Volusia County, Florida: Florida Geol. Survey Rept. Inv. 22. Young, E. J. (see Altschuler, Z. S., 1958, 1960)
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\ , I I ' OS =ase c:11n11iled tram US. Geofcgicar 3ur,ay tooagrollhic quadrangles. a2 55' 50' 45' 40' 35' 0 2 3 4 1 -5 6mifes Figure 4. Map showing the location of selected wells. I 30 1 EXPLANATION 1 e Well 25' 9)0• 11)2 21,22 11• 18 ",s 15.~ 6 6•. 14 7,8 20' _ :)NSET B 18 2 17J9. .is.,s 5 I INSET E INSET F N r ,o 15 05' 28' 55' 50' a1' ij t' r I
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e2aaa' 05' 82Q0 1 55• so' 45 1 40 1 35' 30 1 2f) 1 20 1 15' ,o 81' 25 12 23'~-r---:-----:-.....,..---rr-.-r--"T"'"""""T""""-,-"TT"--T--,-----r-,--r-----r----r---r-r---r---r------r---r---r-r-"l--""T"""'lr-T""---r---r--ir---r---r--,----r-r----ir---r--r.---,-"'-'-i----i--r--'-'~-i--.-r-....;;;,.;---,---,,---r--,----i----T"--,,--,,--..-.:.;=....-,.--.-;;;..;.. 28' >L l I 55 ' 'I L I I i r I I r I r I 50l r t 45 I (.'.) ::J 0 0: 0 I m 1~ en 1.J _J ,~ _j [---+-21'"3ff' MANATE~ co_ I 82' OS eas c:lfflPi led f,am. U S. Geological 5~ topographic quad,angres. 91 . ,,, 90 .86 e, 8755 1 ~'126 84 @ ,.84 .84 8:S .85 7]7;, ---~ Q 88. POLK ----. UN TY 45' . I 1% 0\ \.. .''2 . ,,,L. 112./J ,,, r -~'---, ""'.. ef.2 I J •!.4 t.__ r '\ I e/.7 Ll •:!.Z e l.8 '\ .3.3 ' I 3.4 \\ N t ! .,.. . •. , l ::;.. .45 .,., o ! ,,:, ... f' . I \ I O 10 20miles ' , L------... __________ .) Mop showing net decl i ne of water levels I in feet durrng measurement period N EXPLANATION 102 Well 124 Wei Ibeing pumped 20 1 15' ,, r=~ Number is water le'/el, in feet above mean sea level. ,P--120 _.,,,,,, Piezometric contour showing approximate altitude of the piezometric surface ; Contour Interval 10 "feet ; Datum is mean sea level , 05 1 ,,, •IOo. I \ \JOI I 94 '-~ j4 40 1 . 35 1 30 1 25 1 0 I 2 3 4 5 6 rriiles 28 1 \ ~ . ... . ,r' .r-.,. \ '?'? (,> 20 1 15 1 A,reo of artesian flow 0 Depression contour indicates pumpoge ,o 55 1 50' 45' . 40 1 27 1 a, 0 01 Hydrology by H . G Stewart, Jr . Figure 20. Piezometric contour map of the Floridan aquifer ( October 1959 to February 1960).
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