Investigation of the geology, hydrogeology, and hydrochemistry of the Lower Suwannee River Basin ( FGS: Report of investigation 96 )

STATE OF FLORIDA
DEPARTMENT OF NATURAL RESOURCES
Elton J. Gissendanner, Executive Director

DIVISION OF RESOURCE MANAGEMENT
Art Wilde, Director

BUREAU OF GEOLOGY
Walter Schmidt, Chief

REPORT OF INVESTIGATION NO. 96

AN INVESTIGATION OF THE GEOLOGY, HYDROGEOLOGY, AND
HYDROCHEMISTRY OF THE LOWER
SUWANNEE RIVER BASIN

by

James J. Crane

Published for the

Florida Geological Survey
in cooperation with the
Suwannee River
Water Management District
Tallahassee
1986

DEPARTMENT
OF
NATURAL RESOURCES

BOB GRAHAM
Governor

GEORGE FIRESTONE
Secretary of State

BILL GUNTER
Treasurer

RALPH D. TURLINGTON
Commissioner of Education

JIM SMITH
Attorney General

GERALD A. LEWIS
Comptroller

DOYLE CONNER
Commissioner of Agriculture

ELTON J. GISSENDANNER
Executive Director

LETTER OF TRANSMITTAL

BUREAU OF GEOLOGY
TALLAHASSEE
August 1986

Governor Bob Graham, Chairman
Florida Department of Natural Resources
Tallahassee, Florida 32301

Dear Governor Graham:

The Bureau of Geology, Division of Resource Management, Depart-
ment of Natural Resources, is publishing as its Report of Investigation
No. 96, An Investigation of the Geology, Hydrogeology, and Hydro-
chemistry of the Lower Suwannee River Basin. This report presents basic
geochemical data which will act as a baseline for future comparisons of
water quality in the Lower Suwannee River Basin. This information will
be necessary for regional resource and developmental planning.

Respectfully yours,

Walter Schmidt, Chief
Bureau of Geology

Printed for the
Florida Geological Survey

Tallahassee
1986

iv

TABLE OF CONTENTS

Page

A abstract .......................................... xiii
Acknowledgements ................................. xiv
Introduction ........................................ 1
Metric Conversion Factors .......................... 3
Description of Study Area ............................. 3
Location and Definition ............................ 3
Climate ........................................ 4
Drainage System ................................. 5
Soils .......................................... 6
Vegetation ............................. ........ 7
Regional Economy and Demography ................... 7
Physiography and Geology ............................. 9
Regional Physiography ............................. 9
Regional Structure ................................ 15
Regional Stratigraphy .............................. 18
Pre-Cenozoic Stratigraphy ......................... 18
Cenozoic Stratigraphy ............................ 20
Historical Review ............................. 20
Cedar Keys Formation ....................... 20
Oldsmar Limestone ......................... 21
Lake City Limestone ........................ 22
Avon Park Limestone ....................... 22
Ocala Limestone ........................... 23
Suwannee Limestone ....................... 24
St. Marks Formation ........................ 24
Hawthorn Formation ........................ 25
Alachua Formation ......................... 26
Stratigraphic Nomenclature:
Problems and Usage in this Study ................. 27
Geology of the Lower Suwannee River Basin ......... 29
Previous Investigations .................... . 29
Methods of Investigation and Data
Collection ................................ 30
Stratigraphy ........ ...................... 32
Undifferentiated Carbonate
Lithofacies (UCF) ....................... 32
Dolomite Lithofacies (DF) .................... 50
Ocala Group Undifferentiated (OGU) ............ 53
Suwannee Limestone ....................... 57
St. Marks Formation ............ ............ 57

Hawthorn Fm.-"Alachua Fm."
Residuum ................................ 60
Undifferentiated Sands and
Sandy Clays .............................. 60
Local Structure ............................... 62
Hydrogeology ...................................... 62
Previous Investigations ............................ 62
M ethods ....................................... 64
Results and Discussion ............................ 64
Groundwater Flow and Fluctuation ................ 64
Springs ..................................... 78
Groundwater Chemistry ............................... 81
Previous Investigations ............................ 81
M ethods .................. ..................... 82
Sample Collection and Analysis ................... 82
Data Processing .............................. 82
Results and Discussion ............................ 84
Geochemical Patterns and Distribution .............. 84
Statistical Interpretation of the
Hydrochemical Data ........................... 102
Uranium Hydrogeochemistry ............................ 122
Historical Review ................................. 122
Uranium Fractionation and
Disequilibrium ................................ 122
Fractionation Mechanisms ....................... 124
Occurrence and Distribution ..................... 126
The Use of the Disequilibrium
Concept in Hydrologic Investigations ............... 127
Sam ple Collection ................................ 127
Sample Processing and Analysis ................... .. 128
Results and Discussion ............................ 131
Statistical Interpretation of the
Integrated Hydrochemical and
Uranium Data ................................ 131
Distributional Patterns of Uranium
Parameters and their Significance ................. 135
Groundwater-Surface Water Relationships ................. 145
Summary and Conclusions ............................. 150
References ........................................ 152
Appendices
I. Description of Cuttings and Cores ................ 167
II. Well Data From Cuttings and Cores
Grouped by Cross-Sections on Which
the Data Were Utilized ........................ 186

Ill. W ell Location Information ...................... 204

ILLUSTRATIONS

Figure Page
1 Suwannee River Drainage Basin and sub-basins that com-
prise the basin ................................. 4
2 Distribution of soil types defined by their drainage charac-
teristics ...................................... 8
3 Map of Florida showing 1) the major trans-peninsular phys-
iographic divisions and 2) the Lower Suwannee River Basin
study area .................................... 10
4 Physiographic features located in the Lower Suwannee
River Basin and vicinity ........................... 11
5 Marine terraces located in the Lower Suwannee River
Basin ........................................ 14
6 Map of Florida showing major structural features ........ 16
7 Generalized geologic column for the study area ......... 19
8 Distribution of surficial sediments (having a thickness
greater than 10 feet) in the Lower Suwannee River Basin
and vicinity .................................... 31
9 Map showing 1) locations of wells used to construct north-
south geologic cross-sections, and 2) locations of wells not
used on cross-sections, but used in the construction of
other geologic figures ............................ 33
10 Geologic cross-section A-A'. Location
shown on Figure 9 .............................. 34
11 Geologic cross-section A'-A". Location
show n on Figure 9 .............................. 35
12 Geologic cross-section B-B'. Location
show n on Figure 9 .............................. 36
13 Geologic cross-section B'-B". Location
show n on Figure 9 .............................. 37
14 Geologic cross-section C-C'. Location
show n on Figure 9 .............................. 38
15 Geologic cross-section C'-C". Location
show n on Figure 9 .............................. 39
16 Map showing locations of wells used to construct west-
east geologic cross-sections ....................... 40
17 Geologic cross-section D-D'. Location
shown on Figure 16 ............................. 41
18 Geologic cross-section E-E'. Location
shown on Figure 16 ............................. 42

19 Geologic cross-section F-F'. Location
shown on Figure 16 ............................. 43
20 Geologic cross-section G-G'. Location
shown on Figure 16 ............................. 44
21 Geologic cross-section H-H'. Location
shown on Figure 16 ............................. 45
22 Geologic cross-sections I-I' and J-J'. Locations
shown on Figure 16 ............................. 46
23 Geologic cross-section K-K'. Location
shown on Figure 16 ............................. 47
24 Geologic cross-section L-L'. Location
shown on Figure 16 ............................. 48
25 Geologic cross-section M-M'. Location
shown on Figure 16 ............................. 49
26 Geologic cross-section N-N'. Location
shown on Figure 16 ............................. 50
27 Geologic cross-sections 0-0' and P-P'. Locations
shown on Figure 16 ............................. 51
28 Geologic cross-sections Q-Q' and R-R'. Locations
shown on Figure 16 ............................. 52
29 Structural contour map of the top of the Dolomitic Litho-
facies (DF) in the Lower Suwannee River Basin ......... 54
30 Thickness of the Ocala Group Undifferentiated (OGU) in the
Lower Suwannee River Basin ...................... 55
31 Elevation of the top of the Ocala Group Undifferentiated
(OGU) in the Lower Suwannee River Basin ............. 56
32 Thickness of the Suwannee Limestone in the Lower
Suwannee River Basin ............................ 58
33 Elevation of the top of the Suwannee Limestone in the
Lower Suwannee River Basin ...................... 59
34 Thickness of the sands and sandy clays, including the
Hawthorn Fm. and "Alachua Fm.," where present, in the
Lower Suwannee River Basin ...................... 61
35 Location of several structural features, the Bronson Graben
and Long Pond Fault, proposed by Vernon and Puri ...... 63
36 Hydrogeological classification of the Lower Suwannee River
Basin and vicinity ............................... 65
37 Extent of the surficial aquifier in the Upper
Suwannee River Basin and the northeast portion of the
Lower Suwannee River Basin ...................... 66
38 Potentiometric surface of the Floridan aquifer in the Lower
Suwannee River Basin, May 1980 ................... 69

39 Potentiometric surface of the Floridan aquifer in the Lower
Suwannee River Basin, November 1980 .............. 70
40 Potentiometric surface of the Floridan aquifer in the Lower
Suwannee River Basin, April, 1981 .................. 71
41 Areas of natural recharge to the Floridan aquifer relative to
the potentiometric surface of the Floridan aquifer,
M ay 1980 .................................... 72
42 Map showing 1) the well location and the associated per-
centage of water level measurements in which the water
level measurement at the well varied 5 feet or more from
the previous measurement event at the well and 2) the
locations of USGS Water Level Measurement Wells ...... 74
43 Rainfall from January 1979 to March 1981 at White
Springs, Suwannee Springs, and Cedar Keys in the Lower
Suwannee River Basin (upper) and water well level
elevations from January 1979 to March 1981 at the same
sites (lower) ................................... 76
44 Rainfall from January 1979 to March 1981 at Lake City,
Mayo, and Trenton in the Lower Suwannee River Basin
(upper) and water well level elevations from January 1979
to March 1981 at the same sites (lower) .............. 77
45 Map showing 1) Suwannee River Water Management Dis-
trict monitor wells in the Lower Suwannee River Basin and
vicinity, and 2) springs in the LSRB and vicinity ......... 79
46 A generalized cross-section of a typical spring in the karstic
Lower Suwannee River Basin ...................... 80
47 Distribution of pH values measured in wells and springs in
the Lower Suwannee River Basin and Lake City area ..... 85
48 Distribution of specific conductivity values measured in
wells and springs in the Lower Suwannee River Basin and
Lake City area ................................. 86
49 Distribution of alkalinity values measured in wells and
springs in the Lower Suwannee River Basin and Lake City
area .................. .................... .. 88
50 Distribution of chloride values measured in wells and
springs in the Lower Suwannee River Basin and Lake City
area . . . . . . . . . . . . . . . . . . . . 8 9
51 Distribution of fluoride values measured in wells and
springs in the Lower Suwannee River Basin and Lake City
area . . . . . . . . . . . . . . . . .. . . . 90
52 Distribution of sulfate values measured in wells and springs
in the Lower Suwannee River Basin and Lake City area ... 91
53 Distribution of silica values measured in wells and springs
in the Lower Suwannee River Basin and Lake City area ... 92

54 Distribution of orthophosphate values measured in wells
and springs in the Lower Suwannee River Basin and Lake
City area ..................................... 93
55 Distribution of nitrate values measured in wells and springs
in the Lower Suwannee River Basin and Lake City area ... 95
56 Distribution of ammonia values measured in wells and
springs in the Lower Suwannee River Basin and Lake City
area ......................................... 96
57 Distribution of calcium values measured in wells and
springs in the Lower Suwannee River Basin and Lake City
area ......................................... 97
58 Distribution of magnesium values measured in wells and
springs in the Lower Suwannee River Basin and Lake City
area ......................................... 98
59 Distribution of sodium values measured in wells and
springs in the Lower Suwannee River Basin and Lake City
area ........................................ 99
60 Distribution of potassium values measured in wells and
springs in the Lower Suwannee River Basin and Lake City
area ......................................... 100
61 Distribution of magnesium-to-calcium ratios determined
from well and spring data collected in the Lower Suwannee
River Basin and Lake City area ..................... 101
62 Distribution of the carbonate aquifer factor I, derived from
merged SURFIC-FLORID data, in the Lower Suwannee River
Basin and Lake City area .......................... 116
63 Distribution of the Hawthorn factor II, derived from merged
SURFIC-FLORID data, in the Lower Suwannee River Basin
and Lake City area .............................. 117
64 Distribution of the salt contamination-agricultural contami-
nation factor III, derived from submerged SURFIC-FLORID
data, in the Lower Suwannee River Basin and Lake City
area ...................................... ... 118
65 Distribution of Hawthorn factor I, derived from FLORID
data, in the Lower Suwannee River Basin and Lake City
area .......................................... 120
66 Distribution of Floridan factor II, derived from FLORID data,
in the Lower Suwannee River Basin and Lake City area ... 121
67 Distribution of culturally influenced factor III, derived from
FLORID data, in the Lower Suwannee River Basin and Lake
City area ..................................... 123
68 The first portion of the U-238 decay series ............ 125
69 Alpha spectrum of a groundwater sample from a Lafayette
County w ell ................................... 130

70 Map showing 1) locations of springs and wells at which
samples for uranium analyses were collected and, 2) distri-
bution of surficial sediments in the Lower Suwannee River
Basin and vicinity ............................... 141
71 Relationship between uranium concentration and U-234/
U-238 ratio for spring, well, and river samples collected in
the Lower Suwannee River Basin .................... 143
72 Discharge and specific conductance from October 1978 to
August 1980 for the Suwannee River at White Springs
(left); Discharge and specific conductance from October
1978 to September 1980 for the Suwannee River at Ben-
ton (right) ..................................... 146
73 Discharge and specific conductance from October 1978 to
September 1980 for the Withlacoochee River at Pinetta
(left); Discharge and specific conductance from October
1978 to September 1980 for the Suwannee River at
Suwannee Springs (right) ......................... 147
74 Discharge and specific conductance from October 1978 to
September 1980 for the Suwannee River at Branford (left);
Discharge and specific conductance from October 1978 to
August 1980 for the Suwannee River at Wilcox (right) .... 148

TABLES

Table Page

1 Pearson's Coefficient Matrix- Untransformed FLORID
D ata ......................................... 104
2 Pearson's Coefficient Matrix- Transformed FLORID Data 105
3 Kendall Tau Coefficient Matrix- Untransformed FLORID
Data ......................................... 106
4 Pearson's Coefficient Matrix- Untransformed SURFIC
Data ......................................... 107
5 Pearson's Coefficient Matrix- Transformed SURFIC Data 108
6 Comparison of Parameter Associations Delineated by Aqui-
fer and by Analyses ............................. 109
7 R-Mode Factor Loadings for the Most Significant Variables
(Merged SURFIC-FLORID Data) and Resulting Factors .... 111
8 R-Mode Factor Loadings for the Most Significant Variables
(FLORID data) and Resulting Factors ................. 112
9 R-Mode Factor Loadings for the Most Significant Variables
(SURFIC Data) and Resulting Factors ................. 113

10 Factor Site Scores-Transformed SURFIC Data ......... 119
11 R-Mode Factor Loadings for the Most Significant Variables
(Springs Data) and Resulting Factors ................. 132
12 R-Mode Factor Loadings for the Most Significant Variables
(Wells Data) and Resulting Factors .................. 134
13 Recharge Potential, Uranium Data and Factor Analysis
Results for Selected Springs ....................... 136
14 Recharge Potential, Uranium Data, and Factor Analysis
Results for Selected W ells ......................... 138

ABSTRACT

The purposes of this study were two-fold: (1) to conduct a unified
comprehensive investigation of the hydrogeology of a basin located in a
carbonate terrain; and (2) to collect baseline data to determine the
present state of the Lower Suwannee River system for future compari-
sons. This study defines the geologic and hydrogeologic characteristics
of the Lower Suwannee River Basin, Florida. These data were utilized in
an interpretation of how geologic characteristics of the basin influence
groundwater conditions and how groundwater and surface waters inter-
act. This research is believed to be the first basin study that incorporates
multivariate factor analysis and uranium disequilibrium methodology as
an integral part of a carbonate basin study.
All of the area within the Lower Suwannee River Basin is underlain by
limestones and dolomites. Except for the portion of the basin covered by
Miocene and younger sands and clays, these deposits lie at or near the
surface. Solution of the carbonates has resulted in the development of a
karst plain. Examination of 222 sets of well cuttings, 67 sets of auger
samples and six cores permitted the construction of geology cross sec-
tions that show the Ocala Group limestones and, to a lesser extent, the
Suwannee Limestone as the major lithologic components of the Upper
Floridan aquifer.
Utilizing R-mode factor analysis and correlation coefficient analyses, it
was possible to distinguish water samples from wells completed into a
surficial aquifer from those completed into the Floridan aquifer. Three
water masses were delineated in the Upper Floridan aquifer utilizing the
same analyses.
Analyses for uranium parameters were performed on water samples
from 62 wells, 32 springs, and five river sites. Factor analysis showed an
inverse relationship between the U-238 concentration and the U-234/U-
238 activity ratio; however, the uranium parameters were not associated
with any of the other parameters measured.
The activity ratios for wells and springs ranged from 0.390.02 to
2.570.60. The uranium concentrations ranged from less than 0.02
parts per billion (ppb) to 44.80.11 ppb. Generally, high ratio-low con-
centration values are associated with areas of very low to moderate
recharge to the Floridan aquifer, whereas the low ratio-high concentra-
tion values are usually associated with areas of high recharge.
The Lower Suwannee River is almost totally dependent on ground-
water contributions for its flow. Both river hydrochemical data and the
uranium disequilibrium results supported this conclusion.

ACKNOWLEDGEMENTS

I would like to express my sincere appreciation to Dr. James B. Cowart
for his guidance and patience through many long hours during the course
of this research. I also wish to thank Dr. William C. Burnett, Dr. George
DeVore, Dr. J. Kenneth Osmond, and Dr. William Parker, for their helpful
suggestions and critical review of the manuscript. Appreciation is also
extended to Dr. Ramil Wright for his guidance in the initial phase of this
research, to members of the Florida Bureau of Geology, particularly Dr.
Walter Schmidt and Dr. Thomas M. Scott for their helpful suggestions
and encouragement, and to members of the Suwannee River Water Man-
agement District, particularly Mr. Rick Copeland, Mr. Ron Ceryak, Mr.
Terry Burnson, and Mr. David Fisk for their helpful suggestions.
Figure preparation services were performed by members of the draft-
ing staff at the Florida Bureau of Geology and Ms. Matilda Munoz of the
Northwest Florida Water Management District. Typing services were
performed by Ms. Lilliam Morse and Mrs. Pat Dixon.
This project was partially funded by a student research assistantship
from the Suwannee River Water Management District. The District also
provided laboratory services, field help and field vehicles.

xiv

AN INVESTIGATION OF THE GEOLOGY, HYDROGEOLOGY, AND
HYDROCHEMISTRY OF THE LOWER SUWANNEE RIVER BASIN

by
James J. Crane

INTRODUCTION

Until recently, little impetus or funding was available for research of
the water resources of the Suwannee River Basin due to its lack of
population, lack of heavy industrial development and subsequent lack of
water use conflicts. In the late 1970's, an increasing governmental
awareness emerged that the water resources of the Suwannee River
Basin are of regional and statewide importance (Florida Division of State
Planning, 1977; Florida Dept. of Environmental Regulation, 1980a). In
order to adequately and wisely manage the resources of the Suwannee
River in the presence of increasing multi-use demands for these
resources, various governmental agencies are attempting to develop an
understanding of this hydrologic system. One of these agencies, the
Suwannee River Water Management District (SRWMD), has conducted
previous studies of the Alapaha River Basin (Ceryak, 1977) and of the
Upper Suwannee River Basin (Ceryak et al., 1983).
The purposes of this study are two-fold: (1) to conduct a unified com-
prehensive investigation of the hydrogeology of a basin located in a
carbonate terrain in the mode suggested by Stringfield and LeGrand
(1969) and LeGrand and Stringfield (1973) and (2) to collect baseline
data to determine the present state of the system in order to provide a
basis for future comparisons. This study defines the geologic and hydro-
geologic characteristics of the Lower Suwannee River Basin, Florida. It
includes description of the geology of the basin, definition of the physical
and chemical characteristics of the hydrogeologic units and their ground-
water, and description of the surface physical hydrology and water qual-
ity. These data are utilized in an interpretation of how geologic character-
istics of the basin influence groundwater conditions and how
groundwater and surface waters interact.
The geological description of the basin includes surficial geology and
physiography, and subsurface stratigraphy and structure. Information for
this description was compiled from available data of the Florida Bureau of
Geology and from field investigations. The subsurface stratigraphy was
developed through analyses of well cuttings, cores, rock boring logs,
outcrops and other data sources. This material is available at the Florida
Bureau of Geology, Tallahassee, Florida.
The hydrogeologic units were defined using geologic and water chem-
istry data available from Suwannee River Water Management District
(SRWMD), the U.S. Geological Survey (USGS), the Florida Bureau of
Geology, and data collected during field work carried out in the course of
this study. Available water quality data were compiled for wells and
springs in the basin. Water samples were collected from selected springs

BUREAU OF GEOLOGY

and wells in the basin. These water samples were analyzed for the fol-
lowing constituents: pH, temperature, specific conductivity, alkalinity,
nitrate, ammonia, sulfate, chloride, fluoride, silica, dissolved orthophos-
phate, calcium, magnesium, sodium and potassium. The water chemis-
try data and their relationship to hydrogeologic parameters were ana-
lyzed using graphical techniques and factor analysis in order to identify
water masses in the hydrogeologic units. Representative water samples
were analyzed for heavy radioactive element concentrations and isotope
abundances.
Potentiometric surfaces were plotted to determine seasonal and other
fluctuations in the groundwater levels using USGS and SRWMD data.
Streamflow and surface water chemistry were described using data from
the above agencies.
Compilation of the data provided a comprehensive data-base for the
Lower Suwannee River Basin. In addition, these data were analyzed in
the context of determining the flow patterns, origins, and chemical histo-
ries of groundwater masses. Lawrence and Upchurch (1978) utilized
factor analysis to identify geochemical patterns in groundwater of the
upper Floridan aquifer near Lake City, Florida. They were able to distin-
guish three clusters corresponding to: (1) waters that were in the aquifer
the longest, (2) waters that were recharged through plastic layers, and
(3) waters that were recharged by direct connection with the surface.
Ceryak (1977) utilized the same type of analysis on waters from wells of
varying depths in the Alapaha River Basin. He found three clusters that
corresponded to a perched aquifer, a secondary artesian aquifer, and the
Floridan artesian aquifer. This type of analysis was used in the present
study in order to determine potential recharge and discharge areas, the
relationship of the surface waters to the groundwaters, the relationship
of the lithology to the water chemistry, the role of springs in the hydro-
geologic system, and the groundwater flow pattern.
Kwader (1979) used uranium disequilibrium methods to infer ground-
water flow patterns in the upper Floridan aquifer of northwest Florida.
Kaufmann and others (1969), using the isotope methods, found a close
association between uranium isotope disequilibrium and the hydrogeolo-
gic framework, permitting interpretation of the regional permeability,
groundwater circulation patterns and areas of leaching within the Flori-
dan aquifer of northwest Florida. This type of analysis was also used in
this present study in the interpretation of the Lower Suwannee River
Basin.
Utilizing all available methods, this study attempts to provide a more
complete understanding of the hydrogeological system of a carbonate
terrain area. This study examines in detail the complex karstic hydrology
of an area of the United States where the interaction between ground-
water and surface water is extremely intricate (Stringfield, 1964).
The research contributes original information on the complex interac-
tion of various components of a karstic system. This study utilizes an
integrated approach to the analysis of such a system and employs vari-
ous analytical tools to examine the system from several perspectives. It

REPORT OF INVESTIGATION NO. 96

is believed that this is the first basin study that incorporates multivariate
factor analysis and uranium disequilibrium methodology as an integral
part of the study.

METRIC CONVERSION FACTORS

The Florida Bureau of Geology, in order to prevent duplication of paren-
thetical conversion units, inserts a tabular listing of conversion factors to
obtain metric units.

Multiply by to obtain
feet 0.3048 meters
inches 25.4 millimeters
inches 0.0254 meters
miles 1.6090 kilometers
sq. miles 2.590 sq. kilometers
cubic feet/second 35.314 cubic meters/second

DESCRIPTION OF STUDY AREA
Location and Definition of Study Area
The Suwannee River Basin drains portions of two states, Florida and
Georgia, encompassing a total area of 11,030 square miles. Approxi-
mately 4,260 square miles of the drainage area are located in northwest-
ern Florida (Conover and Leach, 1975); the remainder of the watershed
drains parts of south central Georgia. Encompassing a total distance of
245 miles from its headwaters, the Suwannee River ultimately dis-
charges into the Gulf of Mexico.
The Suwannee River Basin can be divided into five sub-basins (Figure
1): the Suwannee River Basin above the Withlacoochee River (Upper
Suwannee River Basin), the Withlacoochee River Basin, the Alapaha
River Basin, the Santa Fe River Basin and the Suwannee River Basin
below the Withlacoochee River (Lower Suwannee River Basin). The
boundaries of these sub-basins are based upon surface drainage pat-
terns; thus, the groundwater boundaries do not correspond exactly with
these boundaries. The surface waters do have a close relationship with
the groundwater in the basin; thus, the surface drainage boundaries will
be utilized as groundwater basin boundaries.
In this study, the term Suwannee River Basin will be defined as that
basin composed of the Upper Suwannee River Basin (USRB) and the
Lower Suwannee River Basin (LSRB). The Lower Suwannee River Basin
begins at the junction of the Withlacoochee River where the Suwannee
River resumes its southerly course.
The study area generally encompasses the Lower Suwannee River
Basin, although small portions of the Upper Suwannee River Basin, the
Santa Fe River Basin, and the coastal basin are included. This occurs
because the total area of a township-range block intersected by the
Lower Suwannee River Basin boundary line was included within the

BUREAU OF GEOLOGY

Figure 1. Suwannee River Drainage Basin and
subbasins that comprise the basin,
after Florida Dept. of Environmental
Regulation (1980b).

study area. This was done to facilitate computer retrieval of groundwater
data and well lithology data.
Climate
The Suwannee River Basin is characterized by long, warm summers
and mild winters. During the warmest months (June, July, August), the
mean maximum temperature is 91 F; the mean minimum temperature
for these months is 720F. The proximity of the Gulf of Mexico and the
Atlantic Ocean results in a relatively high humidity.
In winter months (December, January, February), this basin frequently
comes under the influence of Canadian air masses, resulting in some
freezing temperatures, rarely less than 200F in the north and 240F in the
south. Most winter cold spells are of short duration and temperatures
usually are above freezing, even on the coldest days. The mean maxi-
mum temperature in January ranges from 670F in the north to 700F in
the south; the January minimums range from 420F in the north to 480F
in the south (Bradley, 1972).
Rainfall averages 52 inches per year, but wide variations occur
between locations and from year to year. The mean seasonal rainfall,

REPORT OF INVESTIGATION NO. 96

1931 -60, for spring, summer, fall, and winter is 10, 20, 12, and 9
inches, respectively (Hughes et al., 1971). About half of the average
annual rainfall falls from June through September. A shorter rainy season
occurs from late February to late April. Some of the highest stages on
record for the Suwannee River have been the result of early spring rains.
Most summer rain comes from short duration afternoon or early evening
local showers and thunderstorms. These rainstorms occasionally pro-
duce 2 3 inches of rain in 1 to 2 hours. The winter and early spring rains
are generally associated with large-scale weather frontal developments
and are occasionally of long duration, from 12 to 36 hours (Florida Dept.
of Environmental Regulation, 1975). November is normally the driest
month of the year. Tropical storms, which may occur from June through
November, are the major causes of widespread, excessive rainfall and
associated flooding. Severe droughts usually occur during the fall and
late spring (Florida Dept. of Environmental Regulation, 1975).
The average annual lake evaporation for the basin is approximately 46
inches. The amount of water available for surface runoff and ground-
water recharge is the difference between rainfall and potential evapora-
tion, about 6 9 inches annually in the basin. In the swampy areas of the
basin, evaporation losses are almost equal to potential evaporation. On
the other hand, where the land is not swampy or dissected by a surface
stream drainage network, much of the rainfall moves downward rapidly
to the water table without large evaporation losses (Visher and Hughes,
1975).

Drainage System

The Suwannee River and its three largest tributaries, the Alapaha,
Withlacoochee, and Santa Fe rivers, are similar in that their channels are
15 to 30-feet deep and often cut through shallow overburden into under-
lying limestone formations.
The Suwannee River originates in the Okefenokee Swamp area of
south Georgia, near Fargo. The swamp covers approximately 680 square
miles, three-fourths of which drain into the Suwannee River. The Suwan-
nee River flows through the swamp for about 28 miles, but is not well-
defined from the adjacent swampland. After flowing over an earthen
dam on the southwest side of the swamp, the river begins its flow
southward. The river channel is superimposed on as much as 300 feet of
sandy clays, clayey sands, sandstone, and limestone overlying the Flori-
dan aquifer. The flow for this portion of the river is supplied by surface
runoff from tributaries draining the swamps, marshes, flatwoods, lakes,
and ponds and by seepage from the surficial aquifer.
Beginning at White Springs, the river channel deepens; its banks
become higher and steeper, and the river is incised into carbonate rocks
of the Floridan aquifer. The river is characterized by limestone outcrops
and shoals. At this point, freshwater springs begin to contribute signifi-
cantly to the river's flow. Near White Springs, the Suwannee River
changes its course and flows westward until it reaches Ellaville where it

BUREAU OF GEOLOGY

resumes its southward path to the coast. The Withlacoochee River joins
the Suwannee River near Ellaville.
The lower section of the Suwannee is characterized by lower eleva-
tions and relief. The only major tributary to the Suwannee River down-
stream of its confluence with the Withlacoochee River is the Santa Fe
River. The surface drainage system has generally been replaced by a
subsurface drainage system composed of well-drained, sandy soils and
solution channels in the underlying limestone. South of Ellaville, numer-
ous springs alter the flow and quality of the river water. Near Branford,
the river channel enters the broad, flat coastal lowlands, then broadens
until the flow becomes sluggish between low banks bordered by
marshes and hardwood hammocks.
Below White Springs, the average annual flow increases from 1879
cubic feet per second (cfs) at White Springs to 6580 cfs at Ellaville to
6994 cfs et seq. at Branford and to 10624 cfs at Wilcox. From White
Springs to Branford, the Suwannee River flow increases primarily due to
inflow from the Withlacoochee River and groundwater discharge from
the Floridan aquifer. The Alapaha River adds little to the base flow of the
Suwannee River; however, the Alapaha Rise, thought to be the resur-
gence of the Alapaha River water, does flow into the Suwannee River.
The relatively high base flow at Ellaville is attributed to groundwater
inflow from springs and seepage from the Floridan aquifer. The Santa Fe
River, the only major tributary to the Suwannee River downstream of the
confluence of the Withlacoochee and Suwannee Rivers, derives most of
its base flow and much of its average flow from the Floridan aquifer
discharges (Hull et al., 1981).
Monthly mean peak flows of the Suwannee River in Florida for 1980
occurred in the spring during March and April, associated with precipita-
tion from frontal systems. The lowest 1980 monthly mean flows
occurred in the fall during September (U.S. Geological Survey, 1981).
Total stream flow of the Suwannee River fluctuates annually and season-
ally. The river periodically overflows its banks. Three extreme floods
have occurred in the last 35 years, in 1948, 1959, and 1973 (Florida
Dept. of Environmental Regulation, 1980b). It has been estimated that
the 100-year floodplain has been exceeded on about 50 percent of the
floodplain at least once since 1974 (Suwannee River Water Management
District, 1976). Flooding occurs generally during the spring, February
through April.

Soils

Generally, the soils in the basin are classified as well-to-poorly-drained
sands with loamy subsoils. The soils of the basin are mostly suited for
agricultural uses. Nearly all of the farmland of the basin is found in the
upper Coastal Lowlands. The soils there are predominantly of moderately
fine texture and are easy to manage, except for some localized erosional
tendencies. In the lower Coastal Lowlands, soils are generally sandy; but

REPORT OF INVESTIGATION NO. 96

some areas contain high amounts of clay and organic matter which
inhibit percolation and infiltration. These soils are poorly drained and
difficult to manage, and are used primarily for timber and pasture (Florida
Dept. of Environmental Regulation, 1975).
Soils in the LSRB can be divided into four general categories (Figure 2).
Most of the soils are moderately to well-drained due to the thinness of
the soil layer and/or the high permeability of the sandy soil. Sandy soils
that are poorly-drained and located in areas not subject to flooding gener-
ally are wet due to a high water table or deposition of that soil in low
spots. Some poorly-drained soils have organic matter or clays that limit
downward percolation. Most of the soils in the poorly and very poorly-
drained category are located in areas subject to flooding along rivers,
streams, tidal marshes, or freshwater swamps. The inland swamps are a
result of high water tables due to limited vertical percolation capabilities
of clayey or organic-rich soils or to their location in a groundwater dis-
charge area.

Vegetation

Vegetation along the Suwannee River has adapted to the periodic
flooding characteristics of the river and the variability in topography. The
USDA Soil Conservation Service has classified approximately 75 miles of
river bank and 12 percent of the total basin area as wetlands. These are
predominantly swamp forest wetlands in the upper river and estuarine
marshes toward the river's mouth.
Much of the Suwannee River Basin is commercial pine forest, except
along the forested banks of the Suwannee and its tributaries. In the
immediate vicinity of the river corridor and its floodplain forests, natural
vegetation remains and tree species diversity is very high. Leadon (1980)
reported that floodplain vegetation above Ellaville is exceptionally
diverse, resulting from the successful association of several adjacent
plant community zones.

Regional Economy and Demography

Agriculture and silviculture are the traditional industries of the Suwan-
nee River region. Although phoshate mining has grown significantly and
agriculture has been slowly declining, the overall economy is still agricul-
turally oriented. The phosphate industry of Hamilton County is a major
employer in Hamilton, Suwannee, and Columbia counties. Timber pro-
duction for pulpwood, lumber, and naval stores is the most extensive
land-use activity (Florida Dept. of Environmental Regulation, 1980b). In
1980, 68 percent of the total land area of Suwannee River basin counties
was planted as commercial forests (Terhune and Floyd, 1982). Land use
in the Suwannee River Basin is restricted primarily to forest production
and agricultural uses. There are no major urban centers in the area.

BUREAU OF GEOLOGY

R9E RIOE RIIE

RI2E RI3E R14E RISE RI6E

SANDY, DROUGHT SOILS
NOT SUBJECT TO FLOODING

WELL-DRAINED SOILS NOT
S SUBJECT TO FLOODING

MODERATELY WELL TO
- POORLY DRAINED SOILS
NOT SUBJECT TO FLOODING
POORLY AND VERY POORLY
F DRAINED SOILS SUBJECT
TO FLOODING

SCALE

i

T3S

T4S

T5S

T6S

rTS

Tes

TSs

TIOS

TIIS

T12S

TI3S

T14S

T155

Figure 2. Distribution of soil types defined by their drainage characteris-
tics (modified from Florida Bureau of Comprehensive Plan-
ning, 1974, 1975; and Houston et al., 1965).

REPORT OF INVESTIGATION NO. 96

PHYSIOGRAPHY AND GEOLOGY

Regional Physiography

The physiography of north-central Florida has been discussed by
numerous authors; the more recent are Cooke (1945), MacNeil (1950),
White (1958, 1970), Doering (1960), Purl and Vernon (1964), Alt and
Brooks (1965), and Healy (1975). The most widespread classification
schemes for Florida physiography are based on groupings of geomorphic
features (White, 1970) or elevation zones ("marine terraces") (MacNeil,
1950; Healy, 1975; and others).
The Florida peninsula has been divided into three physiographic zones
(White, 1970): (1) the Northern or Proximal zone; (2) the Central or Mid-
peninsular zone; and (3) the Southern or Distal zone. The zones are
separated along trans-peninsular lines, oriented approximately perpen-
dicular to the long axis of the peninsula (Figure 3). The Northern zone is
characterized by a continuous, broad upland that extends from the north-
ern Florida peninsula westward into the Florida panhandle. The Central
zone is characteristically a discontinuous highland consisting of series of
ridges and broad valleys that parallel the long axis of the peninsula. The
Lower Suwannee River Basin is located in parts of the Northern and
Central zones. The Lower Suwannee River Basin does not extend into the
Distal zone, which is characterized by a broad, flat, gently sloping,
poorly-drained plain, bordered by the Atlantic Ridge on the east.
Major physiographic features of the Northern zone that extend into the
study area are the Northern Highlands and the Gulf Coastal Lowlands
(Figure 4). Major physiographic features of the Central zone that extend
into the study area are the Gulf Coastal Lowlands and the Bell Ridge
(Figure 4). The Gulf Coastal Lowlands extend from the Northern zone
into the Central zone. The Northern Highlands are restricted to the north-
ern parts of the study area. The Northern Highlands in Florida are distin-
guished by a broad upland extending from Putnam County in the east to
the Apalachicola River on the west. Generally, the Northern Highlands lie
above the potentiometric surface of the limestone aquifer that lies
beneath them. Karst features such as sinks, abandoned spring heads,
and dry stream courses are prevalent along the margin of the Northern
Highlands (White, 1970). The Northern Highlands are divided from the
Gulf Coastal Lowlands by an escarpment called the Cody Scarp which is
the most persistent topographic break in Florida, according to Puri and
Vernon (1964). The continuity of the Cody Scarp is broken by the
Suwannee and Withlacoochee rivers in the study area.
Associated with the Northern Highlands is a geomorphic feature called
the Lake City Ridge. This feature, recognized by Pirkle (1972) as a promi-
nent ridge that intersects the Trail Ridge, has elevations from 150 to 215
feet, National Geodetic Vertical Datum (NGVD). This ridge runs from
Lake City to approximately six miles west of Macclenny, where it turns
north to join the Trail Ridge at the St. Marys River. Although the Lake City

10 BUREAU OF GEOLOGY

87a 86' 85* 84 830

U"-- /'- '. R

/0 '3 r/i 3*

/r .- ROX I M A L
SONE ,30*
-..-..--_. <,,,"-..--,,- .i :-..40 4

0
/4/ / o vr

1 0 v A

0 14.S
4 /

/t

\ 'Y4**
/ 2t
a 5 MI'^LS N

;* /c -'o, / J

I I C 26*

o 50 KM
SCALE/

03" 83-" 82 810 80" J

Figure 3. Map of Florida showing 1) the major trans-peninsular physio-
graphic divisions and 2) the Lower Suwannee River Basin
study area (LSRB) (after White, 1970).
/ -
SCALE 014

oo t50 ML / 0
954 83- 82' 81 80

Figure 3. Map of Florida showing 1) the major trans-peninsular physio-
graphic divisions and 2) the Lower Suwannee River Basin
study area (LSRB) (after White, 1970).

REPORT OF INVESTIGATION NO. 96

830 83-00, OZ-,30
+ + -

R9E RIME RIIE RI2E RI3E R14E RISE R16E RI7E

'. .. '"'O '1|

0 5 10 i '

EXPLANATION
NORTHERN HIGHLANDS
-I ,I .. . . ....

W CENTRAL HIGHLANDS

GULF COASTAL LOWLANDS

=-1 COASTAL SWAMPS AND
llJ DROWNED COASTAL KARST

Figure 4. Physiographic features located in the lower Suwannee River
Basin (outlined in black) and vicinity (after White, 1970).

+ so3 oo

T6S

T7S

T85

T9S

TIOS

TIIS
+29- 0'

T14S
+ 29"15'

BUREAU OF GEOLOGY

Ridge as defined by Pirkle (1972) does not lie within the study area, the
Lake City Ridge as redefined in Ceryak et al. (1983) does. They showed
an area east of Live Oak, Florida, and southwest of White Springs, Flor-
ida, to be lithologically, configuratively, and topographically similar to the
ridge described by Pirkle (1972). They redefined the Lake City Ridge to
include this westerly extension. The surface of the ridge is a sandy,
almost level, poorly-to-well-drained area in which surface depressions
and sinkhole lakes are common, the largest of which are Alligator Lake in
Columbia County and Ocean Pond in Baker County (Meyer, 1962).
The Gulf Coastal Lowlands consists of gently sloping plains extending
from the base of the highlands coastward. These plains, generally less
than 100 feet NGVD, lie in an area where the limestone is at or near the
land surface. Extensive solution activity has resulted in a karstic topogra-
phy. The limestone is overlain by a veneer of sand or sandy clay. Devel-
opment of a well-integrated surface drainage pattern has been impeded
in much of the Coastal Lowlands because most precipitation alternatively
evaporates, percolates into the ground, or enters sink features. The few
perennial streams are fed predominantly by springs rather than by sur-
face runoff. Much of the Suwannee River is springfed, especially during
periods of low precipitation.
The major part of the study area lies within the Gulf Coastal Lowlands,
which also include the River Valley Lowlands and Coastal Swamps
within their boundaries. The Suwannee River Lowlands, the Santa Fe
River Lowlands, and the Waccasassa Flats are located on the periphery
of the study area. The Suwannee River Lowlands in Florida extend from
the northern Florida border to the Gulf of Mexico. Although many of the
river valley lowlands transect the Northern Highlands, they are consid-
ered part of the Gulf Coastal Lowlands because of their lower elevations
(Ceryak et al., 1983).
The Coastal Swamps in this Basin are found along the coastal areas of
Dixie and Levy counties, extending as much as 10-15 miles inland.
White (1970) defined the Coastal Swamps as swamps which exist from
the Gulf Coast to a line enclosing all continuous areas of swamp adjacent
to the coast. Muds and silts are deposited in the swamps, which support
a growth of salt marsh and freshwater grasses and other vegetation.
A geomorphic feature associated with the Gulf Coastal Lowlands is
San Pedro Bay, a swamp region located primarily in the northeast corner
of Taylor County. The sands of the bay almost always overlie a thin (less
than five-feet thick), discontinuous, light blue-green clay. The clay unit
tends to retard vertical drainage, thus creating swampy conditions, slow-
ing development of karst activity, and enhancing surface drainage pat-
terns (Copeland and Burnson, in press).
Another feature associated with the Gulf Coastal Lowlands of the
Central zone is Bell Ridge in Gilchrist County (Figure 4). Bell Ridge, actu-
ally two irregularly shaped ridges, represents a relict barrier island that
extended along the western side of the Waccasassa Flats (Puri and
Vernon, 1964). Sand hills near Bell, Florida, occur along the western side

REPORT OF INVESTIGATION NO. 96

of the ridge and are thought to be caused by collapse and differential
sagging of the original islands that were underlain by solution-riddled
limestone (Puri et al., 1967). The sand hills along the western and south-
ern parts of the study area form a drainage divide between the Suwannee
River and the Santa Fe or Waccasassa rivers.
Numerous authors have delineated Florida's physiography by tracing
ancient marine shorelines. The relict features associated with the shore-
lines most frequently used are the marine terraces. A terrace is assumed
to be horizontal and the contour line of the flat surface is traced around
the state as Cooke (1945) and MacNeil (1950) have done. Winkler and
Howard (1977) believe that Cooke's terrace names are meaningless out-
side of their original localities. They report geomorphic evidence that
indicates deformation of persistent Cenozoic structural features, e.g.,
the Ocala Arch and the Southeast Georgia Embayment, continuing
throughout Pliocene and Pleistocene time. Alt and Brooks (1965) stated
that marine terraces are not normally horizontal, but rather, slope gently
seaward so that a terrace associated with a particular shoreline will not
be located at the same elevation throughout its extent. Differences in the
slope of the terrace can occur really for the same shoreline stand. The
karstic nature of central peninsular Florida also poses problems. Pirkle
and Brooks (1959) have pointed out the existence of extensive limestone
plains of karst erosion which are related to former stands of the water
table and have apparently been confused for marine terraces. Also, the
shorelines have been subject to erosion and to sagging caused by solu-
tion and collapse of underlying limestones (White, 1970).
Healy (1975) recognized five marine terraces within the Lower Suwan-
nee River Basin (Figure 5). As discussed previously, it is better to think of
these divisions as topographic elevation zones instead of marine terrace
surfaces associated with particular shoreline stands. Two of these eleva-
tion zones, the Coharie (170-215') and the Okefenokee-Sunderland
(100- 170') are found within the borders of the Northern Highlands. In
the northeast part of the basin, the Coharie zone is represented by the
Lake City Ridge as defined in Ceryak et al. (1983). The Okefenokee-
Sunderland zone includes the higher elevations surrounding the river val-
leys that cut through the Northern Highlands. Although Healy (1975)
defined the Coharie as 170-215' in his text, it appears that he actually
used the 150-foot contour line to delineate the Coharie in Suwannee
County as shown on his map. Since Vernon (1951) and MacNeil (1950)
defined the Okefenokee at 100- 150', this investigator designates the
zone from 150-220' as Coharie, following Vernon (1951). Thus, the
Lake City Ridge, which follows the 150-foot contour rather closely, is
defined as Coharie.
The Gulf Coastal Lowlands consist of three elevation zones, the
Wicomico (70-100'), the Pamlico (8-25'), and ,he Silver Bluff
(1 10'). The Wicomico is the most widespread in the study area. The
Silver Bluff is limited to coastal areas of Dixie and Levy counties and near
the mouth of the Suwannee River. The Pamlico is found in the higher

BUREAU OF GEOLOGY

RISE R16E RI7E

TIS

T2S

EXPLANATION

D 170-215' COHARIE
S100-170' INCLUDES:
SUNDERLAND.OKEFENOKEE

S70-100' WICOMICO
D 8-25' PAMLICO

l .10'SILVER BLUFF

Figure 5. Marine terraces located in the Lower Suwannee River Basin
(outlined in black) (after White, 1970).

4

I uc%

+ 30o 00'
T6S

T 7S

TOS

T9S

T IOS

TIIS
+ 29" 30

TI2S

T13S

+ 2., 5'

REPORT OF INVESTIGATION NO. 96

coastal areas of Dixie and Levy counties and borders the Suwannee River
Lowlands as far north as Branford, Florida.
All of the area within the Lower Suwannee River Basin is underlain by
limestones and dolomites. Except for the portion of the basin covered by
the Miocene and younger sands and clays (primarily the Northern High-
lands), these deposits lie at or near the surface in the remainder of the
basin. Solution of these carbonates has resulted in the development of a
karst plain in the lowlands. The bedrock is greatly fractured and almost
all rain that falls in the area is absorbed by loose sand or captured by
solution zones and fractures in the porous, carbonate bedrock. The
waters entering the bedrock are charged with organic and carbonic acids
from the organic matter in the soil, the carbon dioxide in the atmosphere,
and soil zone respectively (Stringfield et al., 1979). These waters readily
dissolve the carbonate bedrock, producing solution features. Because
the water tends to move through areas of least resistance, fractures,
bedding planes, pores and open spaces, the size of these openings grad-
ually increases, forming networks of vertical and horizontal channels. As
solution proceeds, cavities are cut into the bedrock. Sinkholes form
when the sediments overlying the cavities collapse. Many lakes, sinks,
depressions, and ponds, are the result of solution. Solution features are
initiated at or near the water table, in the vadose zone, and are modified
by the fluctuations of the water table (Puri et al., 1967). Solution fea-
tures found in or near the basin include: (1) sinkholes, (2) funnel sinks
and natural wells, (3) solution pipes, (4) sinkhole lakes, (5) underground
rivers, (6) springs, (7) caves, and (8) karrenfelds.
The Highland-Lowland delineation is marked by the Cody Scarp. Gen-
erally, this contact is represented by a belt 4 to 15-miles wide that is
characterized by mature karst features, including dolines, collapse sinks,
sinkhole lakes, and disappearing streams (Copeland, 1981). Springs are
common in this belt, including such major ones as Alapaha Rise, White
Springs, and Ichetucknee Springs.
The Northern Highland's features are those of youthful karst, marked
by initial development of dolines. The topography is generally flat with a
few scattered sinkhole depressions such as Dexter Lake and Mills Pond
in Suwannee County and Alligator Lake near Lake City in Columbia
County. Mills Pond and Alligator Lake are known to periodically drain
through smaller sinkholes in the bottom of these lakes (Copeland, 1981).
Karst features in the Lowlands are mature; however, collapse sinks
and disappearing streams are rare. The proximity of the water table to
the land surface restricts the formation of the type of sink into which
disappearing streams flow (Copeland, 1981).

Regional Structure

The major structural features within and bordering the Lower Suwan-
nee River Basin are the Peninsular Arch, the Ocala Uplift, and the Suwan-
nee Straits (Figure 6).

BUREAU OF GEOLOGY

Figure 6. Map of Florida showing major structural features (after
Faulkner, 1970).

The eastern portion of the Lower Suwannee River Basin lies on the
western flanks of the Peninsular Arch. The Peninsular Arch, named and
described by Applin (1951), is "the anticlinal fold, or arch, which is
approximately 275 miles long, trends south-southeastward and forms
the axis of the Florida peninsula as far south as the latitude of Lake
Okeechobee." Applin (1951) concluded that the Peninsular Arch had

REPORT OF INVESTIGATION NO. 96

been a dominant subsurface structure since Paleozoic time, although its
present form is due to regional movements during the Mesozoic and
Cenozoic. Puri and Vernon (1964) described the Early Ordovician rocks
that form the crest of the Arch as being topographically high during Early
Cretaceous time. Sediments of Early Cretaceous age were deposited on
the flanks of the Arch, but not until Late Cretaceous were sediments
deposited on the crest of the Arch. The highest elevation of the top of the
Arch reported thus far is 2640 mean sea level (MSL) in central Colum-
bia County (Jordan, 1954).
The term Ocala Uplift was first used in a 1920 press release by the
United States Geological Survey in which a summary of oil possibilities in
Florida based on work by O. B. Hopkins (1920) was reported. Vernon
(1951) described the Ocala Uplift as "an anticline that developed in
Tertiary sediments as a gentle flexure, approximately 230 miles long,
and about 70 miles wide where exposed in central peninsular Florida."
He showed the structure to be active from Late Eocene to Early Miocene
time. Chen (1965) reported the Ocala Uplift to have formed in post-
Oligocene or Early Miocene time. According to Vernon (1951), 0. B.
Hopkins in his press release described two uplifts along the anticline.
One, called the Ocala Uplift, had its crest in eastern Levy County; the
other, called the Live Oak Uplift, had its crest near Live Oak, Florida.
Vernon (1951) discovered that Hopkins' identification of the Live Oak
Uplift was incorrect since it was based upon an erroneous correlation of
the Suwannee Limestone exposed along the Suwannee River with the
Hawthorn Formation cropping out at Live Oak. However, Vernon, after
tracing a bed in the Ocala Limestone, found that the Live Oak area was
indeed structurally high. The crest of the Ocala Uplift separates into two
folds near the northern Levy County line, one which trends north and
passes east of Live Oak and the other which continues the northwest
trend of the original fold. Vernon (1951) believed the courses of the
Suwannee River and the Santa Fe River have been influenced by the
slopes of the bedrock developed along the flanks of these two folds.
Colton (1978) showed that five domes were reflected in the Suwannee
Limestone overlying the Ocala Limestone uplift structures. The White
Springs Dome and the Live Oak Dome are located in the study area.
Although the Ocala Uplift is developed along the flanks of the Peninsular
Arch, Vernon (1951) concluded that the features did not have any struc-
tural association with each other. This conclusion was reached because
wells drilled on the crest of the Ocala Uplift in eastern Citrus and Levy
counties penetrated the Peninsular Arch only after passing through a
thick sequence of Mesozoic sediments. Winston (1976a) proposed that
the Ocala Uplift was not an anticline at all, but a blister dome created by
an anomalous thickening of the Lake City Formation caused by the east-
ward tilting of the Florida peninsula. The exact nature of this structure
has not yet been resolved.
The Suwannee Straits are located just northwest of the Lower Suwan-
nee River Basin. The term Suwannee Strait was first used by Dall and

BUREAU OF GEOLOGY

Harris (1892) to define an area "which separated the continental border
from the Eocene and Miocene islands" in which Hawthorn argillaceous
sediments were deposited. The Okefenokee and Suwannee swamps and
the trough of the Suwannee River were included in the Strait by Dall and
Harris (1892). They estimated the width of the Strait as less than 50
miles. Vaughan (1910) discussed Suwannee Straits and utilized Dall and
Harris's evidence to substantiate erosion of Miocene sediments in the
straits. Applin and Applin (1944) referred to "a channel or trough
extending southwestward across Georgia through the Tallahassee area
of Florida to the Gulf of Mexico." Jordan (1954) recognized this same
structure, Suwannee Strait, as an erosional feature in the subsurface, a
paleochannel formed along the transition zone between the plastic and
carbonate facies of the Cretaceous as a result of regional movement in
Late Cretaceous time. Hull (1962), however, considered the feature to
represent a narrow area (20- 30 miles in width) of nondeposition due to
the effects of oceanic currents. Chen (1965) used the term "Suwannee
Channel" and described it as "the site of relatively thin accumulation of
very fine sands, silts, clays and limestones at least during the time from
late Upper Cretaceous to Lower Eocene." He considered the feature as a
site of very slow deposition during the Paleocene and Eocene, rather than
of differential erosion. Applin and Applin (1967) introduced the term
"Suwannee Saddle" and described it as "a subsurface syncline that
extends about 200 miles in a broad arc from southeastern Georgia to
Jefferson, Leon and Wakulla counties in north-central Florida, bordering
the Peninsular Arch on the north and northwest." They interpreted the
Saddle as an upwarped barrier during Late Cretaceous time and con-
cluded that widespread Tertiary tectonics resulted in the relative depres-
sion of the feature due to uplift of the areas north and south.

Regional Stratigraphy

Much of the state of Florida is the emerged portion of a large mass of
sediments comprising the Florida Plateau. These sediments range in age
from Paleozoic to Recent. The stratigraphic units which have been
reported in the Lower Suwannee River Basin are shown in Figure 7. Most
of the units are relatively thin in north-central Florida, becoming much
thicker southward. The dominant structural features, the Peninsular
Arch and the Ocala Uplift, account for these trends.

PRE-CENOZOIC STRATIGRAPHY

Although Paleozoic and Mesozoic rocks do not constitute freshwater-
bearing strata in Florida, their discussion is important since these strata
form important structures; e.g., Peninsular Arch, which controlled later
deposition and subsequent surficial and subsurface drainage patterns.
Paleozoic rocks have been penetrated in oil wells drilled in the Lower
Suwannee River Basin. The ages of these rocks range from Early Ordovi-

REPORT OF INVESTIGATION NO. 96

I PREVIOUS

STUDIES THIS STUDY

HOLOCENE

PLEISTOCENE

PLIOCENE

M, FRESHWATER
S a MUDS
AN SANDS

IIFFER-
IATED
HANDS

AY
-AYS

SUWANNEE LIMESTONE

F5 UPPER
, ;MEMBER
S LOWER
g. MEMBER

S CRYSTAL
w0r RIVER
4 FORMATION
SWILLISTON
a< FORMATION
F INGLIS
FORMATION

AVON PARK
LIMESTONE

LAKE CITY
LIMESTONE

OLDSMAR
LIMESTONE

CEDAR KEYS
LIMESTONE
GULF SERIES BEDS
GULF SERIES BEDS

0

N

0

Z

LLJ

0

N
I
-J

OCALA GROUP
UNDIFFERENTIATED

UNDIFFERENTIATED
DOLOMITE
LITHOFACIES

UNDIFFERENTIATED
CARBONATE
LITHOFACIES

UNITS NOT
INVESTIGATED
IN THIS STUDY

Figure 7. Generalized geologic column for the study area.

MIOCENE

OLIGOCENE

EOCENE

O

COMANCHE SERIES BEDS
_ *m ---- -
UNDIFFERENTIATED
PALEOZOICS

PALEOCENE

I
UPPER
LOWER
'RETACEOUS
TRIASSIC
DEVONIAN
TO
3RDOVICIAN

r

ALLUVIUM, FRESHWATER MARLS, ALLUVI
Z PEAT
PEATS & MUDS, EOLIAN SANDS Q EOLI
- - - - -- - -

r UND
UNDIFFERENTIATED 2 ENT
SANDS <
8 DI
CLAYS
_j CL
ALACHUA FORMATION -
HAWTHORN FORMATION
ST. MARKS FORMATION

BUREAU OF GEOLOGY

cian to Early Devonian. No well in north Florida has completely pene-
trated the Paleozoic (Winston, 1976b). Most wells have penetrated the
Paleozoic by only a few feet, although a few have penetrated significant
thicknesses (2285 feet in Dixie County). The section consists of two
lithologies, quartzitic sandstones and dark shales. The quartzites are
restricted to the Lower Ordovician while the shales are younger, Middle
Ordovician to Devonian. Most of the ages assigned to these rocks are on
the basis of faunal evidence. Information on the location of these wells
can be found in Puri and Vernon (1964), Barnett (1975), and the Florida
Bureau of Geology Well Log Files in Tallahassee.
Applin (1951) listed seven wells in or near the study area in which
diabase or basalt is penetrated. These rocks, construed to be dikes, sills
and flows, were tentatively identified as Triassic in age on the basis of
stratigraphic relationships.
The Paleozoic units are unconformably overlain by rocks of Early Cre-
taceous age, assigned to the Comanche Series by Applin (1951). In
north-central Florida, these beds grade from a "red bed" facies com-
posed of irregularly interlensing mudstones, siltstones, poorly-sorted fine
to coarse-grained sandstones, and red, green or varicolored shales in the
north to a mixed faces, mainly argillaceous and arenaceous limestone or
dolomites, neritic clastics and some evaporites in the south.
The Comanche beds are overlain unconformably by deposits of the
Gulf Series of late Cretaceous age. The Gulf Series includes the Atkinson
Formation which consists of beds of Woodbine Age and beds of Eagle
Ford Age, beds of Austin Age, beds of Taylor Age, and the Lawson
Limestone of Navarro Age. The Atkinson Formation is composed of dark,
fossiliferous marine shales, fine-grained sandstones, and silty lime-
stones. The beds overlying the Atkinson Formation are composed chiefly
of fossiliferous limestones, dolomites, chalk, and chalky marl. The lower
beds of the Gulf Series wedge out against and are partially absent from
the crest of the Peninsular Arch, suggesting that the Arch was being
uplifted at the time of deposition of basal Gulf Series sediments or that
the Late Cretaceous sea encroached upon an already structurally high
area (Meyer, 1962). These Cretaceous rocks are discussed in great detail
in Applin and Applin (1944), Applin (1951), Vernon (1951), and Puri and
Vernon (1964).

CENOZOIC STRATIGRAPHY

Historical Review
Cedar Keys Formation

The Cedar Keys Formation, the only formation in the Paleocene Series,
was proposed by Cole (1944) for tan-colored, hard limestones which
overlie Cretaceous calcarenite and contain the foraminifer Borelis gunteri
Cole and B. floridanus Cole. As used by Cole, the formation extended
downward from the uppermost occurrence of the Borelis fauna to the top

REPORT OF INVESTIGATION NO. 96

of the Cretaceous strata. The Cretaceous strata were defined on the
basis of the occurrence of certain foraminifera. A thin, basal transition
unit included in the Cedar Keys Formation by Cole is now considered by
most southeastern U.S. geologists to be the upper member of the Law-
son Limestone of late Cretaceous age (Vernon, 1951). Applin and Applin
(1944) and Vernon (1951) amended Cole's definition to include an indef-
inite thickness of beds at the top and to exclude the Upper Cretaceous
beds; however, they still retained the highest occurrence of the Borelis
and associated fauna as the criterion for picking the top of the formation.
Puri and Vernon (1964) reiterated the biostratigraphically-based defini-
tion as published by Vernon (1951). Chen (1965), in an attempt to
present a lithologic definition for the formation, determined the top of the
Cedar Keys Formation to be "marked by a distinct lithology consisting
mainly of gray, microcrystalline, slightly gypsiferous and rarely fossilifer-
ous dolomite", easily recognized on electric logs. The base of the forma-
tion was defined by the presence of a pure, clean, very light brown, and
finely crystalline dolomite and/or chalky dolomitic limestone (Lawson
Limestone of Late Cretaceous age). The upper contact may or may not
correspond to the first occurrence of the Borelis fauna. The Cedar Keys
Formation consists mostly of dolomite and evaporites (gypsum and
anhydrite) with minor amounts of limestone (Chen, 1965).

Oldsmar Limestone

The Oldsmar Limestone was first applied by Applin and Applin (1944)
to non-clastic rocks of Early Eocene age in northern Florida. Their unit
included the interval that is marked at the top by the presence of abun-
dant Heliocostegina gyralis Barber and Grimsdale, and that rests on the
Cedar Keys Limestone. The Oldsmar, as defined by the Applins, is a
series of four faunizones and does not differ lithologically from the over-
lying and underlying formations (Vernon, 1951). The unit was composed
of fragmental marine limestone, partially to completely dolomitized and
containing irregular and rare lenses of chert, gypsum, and thin shale
beds. The Oldsmar Limestone was restricted by Cole and Applin (1964)
to the uppermost occurrence of Pseudophragmina zaragosensis or Cos-
kinolina elongata which are found lower in the section than H. gyralis.
Chen (1965) believed that the Oldsmar was lithologically different from
the underlying Cedar Keys Formation but not from the overlying Lake
City Formation. He defined the top of the Oldsmar by the presence of
chalky white-to-light-brown, pure, finely fragmental, and fossiliferous
limestone overlain by a thick dolomite defined as basal Lake City Forma-
tion. The base of the Oldsmar was defined by a thick, dark brown, pure,
finely to coarsely crystalline dolomite. The Oldsmar Limestone of Chen is
composed of dolomite and limestone with minor amounts of gypsum and
anhydrite. Chen's lithologically-defined units did not necessarily corre-
late with the biostratigraphically-defined unit of the Applins and Vernon.

BUREAU OF GEOLOGY

Lake City Limestone

The Lake City Limestone was erected by Applin and Applin (1944) for
a predominantly chalky to granular limestone of early Middle Eocene age
in northern Florida. They established the top of the unit at the first
appearance of Dictyoconus americanus (Cushman). As thus used, the
unit is actually a biostratigraphic unit. Vernon (1951) and Puri and
Vernon (1964) used a combination of marker beds and diagnostic
foraminifers to pick the top of the Lake City Limestone. These beds
included a pseudo-oolite, a brown-to-coffee-colored chert; a bentonite
clay; and a brownish-gray, laminated, finely crystalline dolomite contain-
ing seams of black carbon and a certain fauna. According to Vernon
(1951), "the formation is characterized by several lithologies which
probably occur as thin beds in a thick carbonate section." The formation
is composed of a matrix of tan-to-cream, fragmental, often peat-flecked,
granular and micritic limestone in which are embedded foraminifera, cal-
cite crystals and echinoid plates. The limestone is irregularly dolomitized
with all stages of dolomitization present, from dolomite crystals in the
matrix to complete dolomite. Anhydrite and gypsum are also found in
cavities and thin beds. The Lake City Limestone was expanded down-
ward by Cole and Applin (1964) to include the Helicostegina gyralis zone
previously used to mark the top of the Oldsmar Limestone. Chen (1965)
attempted to define the lithology in order to bring the formation into
conformity with the International Stratigraphic Code. He picked the top
of the Lake City Limestone by the occurrence of a thin, highly carbona-
ceous unit consisting of thin beds of peat, intercalated with dark brown
to brown-black carbonaceous limestone and dolomite. Unfortunately,
this unit is not present in all areas, especially south Florida. In these
areas, Chen used a brown to dark brown, fragmental, fossiliferous lime-
stone containing Dictyoconus americanus and overlain by a basal dolo-
mite unit of the Avon Park Limestone as his marker for the top of the Lake
City Limestone. Hunter (1976) reported that D. americanus was not a
valid indicator of the Lake City Limestone since the range of the species
was much longer than previously thought. Randazzo (1980) reported
that the Lake City Limestone can be recognized by a combination of
features: presence of highly carbonaceous beds; clay beds; common
quartz; glauconite; gypsum; and poikilotopic fabric as seen in thin sec-
tion.

Avon Park Limestone

Applin and Applin (1944) defined the Avon Park Limestone to include
the upper part of the late Middle Eocene which contains a cream-colored,
chalky limestone and a distinct fauna. In practice, the formation is picked
on the first occurrence of Dictyoconus cookei and associated foramini-
fera. The formation, as originally defined, is primarily a biostratigraphic
unit. Vernon (1951) and Puri and Vernon (1964) noted that the Avon

REPORT OF INVESTIGATION NO. 96

Park Limestone is composed of several lithologies having a common
fauna and a high content of carbonaceous matter. The lithologies
include: a cream-to-brown, highly fossiliferous, miliolid-rich, marine,
fragmental to micritic limestone that weathers cream-to-white and is
purple tinted; a cream-to-brown, micritic and fragmental, peat-flecked
and seamed, very fossiliferous, marine limestone; a tan-to-brown, thin-
bedded and laminated, very finely crystalline, marine dolomite. Chen
(1965) marked the top of the formation by the presence of brown, finely
fragmental and fossiliferous limestone or a brown and finely crystalline
dolomite bed. Chen defined the Avon Park lithologically as composed of
fossiliferous limestone and dolomite with small amounts of evaporites
and carbonaceous matter. Randazzo (1980) marked the top of the Avon
Park by the first occurrence downward of a mid-rock lithofacies which
corresponds with the first occurrence of dolomite. He defined the unit as
a series of interbedded lithologies (mudrock, peloidal rock, and skeletal
rock) which represent distinct depositional cycles.

Ocala Limestone

The term Ocala Limestone was first used by Dall and Harris (1892).
Cooke (1915) established the Ocala Limestone as Eocene and showed
the fauna to be of Jackson Age. Since then the terms Ocala Limestone,
Jackson Group, and Jackson Stage have been used for these Late
Eocene sediments. Applin and Applin (1944) divided the Ocala Lime-
stone into upper and lower members. The upper member is a soft, white,
chalky, porous coquina, composed mainly of large foraminifera. The
lower member is a cream-colored limestone, generally harder than the
upper member, commonly highly calcitic, and composed of molds of
small miliolid foraminifera.
Vernon (1951) divided the Ocala Limestone into two formations, the
Ocala Limestone (restricted) and the underlying Moodys Branch Forma-
tion. He recognized two members in the Moodys Branch Formation, the
Williston and the underlying Inglis. The Inglis Member is a cream-to-tan,
granular to rarely pasty, porous, fairly hard, massive, shallow-water,
marine limestone containing an abundant and bizarre fauna of crustacean
parts, foraminifera, echinoids, and molluscs. The bed may be partially or
completely dolomitized. The Williston Member has two types of lithol-
ogy, a cream-colored coquina of camerinids and miliolids loosely held in
calcite paste; and a cream-to-tan-colored, detrital limestone composed
of small foraminifera and minor amounts of echinoids, molluscs, and
large foraminifera (Vernon, 1951). In practice, this member is picked by
the first occurrence of Operculinoides spp. and Amphistegina pinarensis
cosdeni. The Ocala Limestone (restricted) of Vernon (1951) is typically a
white-to-cream, soft, very massive, friable, coquinoid limestone, com-
posed of large foraminifera (Lepidocyclina spp., Operculinoides spp.) set
in a pasty matrix.
Puri (1953b; 1957), using Vernon's (1951) rock outcrop descriptions

BUREAU OF GEOLOGY

raised both the Williston and Inglis members of the Moodys Branch For-
mation to formational status and renamed the Ocala Limestone
(restricted) the Crystal River Formation. He placed all three formations in
the Ocala Group. Puri differentiated these three formations on the basis
of a detailed biostratigraphic zonation scheme utilizing microfossils.
Later, Cole and Applin (1964) and Hunter (1976) recommended that the
term Inglis Formation be abandoned and the strata be included in the
Avon Park Limestone.

Suwannee Limestone

The name Suwannee Limestone was established by Cooke and Mans-
field (1936) for a hard, crystalline, yellowish limestone, containing the
echinoid Cassidulus gouldii, exposed along the Suwannee River from
Ellaville to White Springs. These strata were previously placed in the
Hawthorn Formation by Mossom (1925) and in the Tampa Limestone by
Cooke and Mossom (1929). The lithology and fauna of the Suwannee
Limestone were described by Cooke (1945). Vernon (1951) included all
beds of Oligocene age in Citrus and Levy counties in the Suwannee
Limestone. He described the formation as a cream-colored, granular,
slightly sandy, detrital, porous, thin-bedded limestone, with abundant
specimens of Dictyoconus cookei, Coskinolina floridana, and the echi-
noid Cassidulus gouldii. He also defined the base of the Suwannee Lime-
stone as a cream-to-tan, thin-bedded, pasty, sub-granular to lithologic,
dense, hard limestone with beds marked by numerous mollusc molds.
Colton (1978) included six lithologies in the Suwannee Limestone. The
most predominant lithologies were a soft, friable calcarenite, composed
of miliolids and other foraminifera slightly cemented by sparry calcite,
and a hard, dense, resonant limestone composed of foraminiferal tests
partly to completely imbedded in dense crystalline calcite. Other litholo-
gies noted by Colton (1978) were sublithographic limestone, intraclastic
limestone, dolomite, and recrystallized limestone.

St. Marks Formation

The sediments presently assigned to the Tampa Stage have been
defined and redefined numerous times. Finch (1823) first used the term
"St. Marks limestone" in his essay on the Tertiary in which he described
molluscs from Wakulla County, Florida. Johnson (1888) applied the term
"Tampa formation" to limestone outcrops near Ballast Point in Hillsbo-
rough County, Florida. Dall and Harris (1892) placed the Tampa, Chipola,
and Alum Bluff beds in a "Tampa group." Matson and Clapp (1909)
included the Tampa formation at the base of the Apalachicola Group,
restricted to south Florida. In 1929, Cooke and Mossom changed the
name "Tampa formation" to "Tampa limestone" due to the predomi-
nance of this lithology and amended the definition to include what had
been the Chattahoochee Formation. Cooke and Mansfield (1936)

REPORT OF INVESTIGATION NO. 96

restricted the previously described Tampa limestone when they erected
their Suwannee limestone. Vernon (1942) resurrected the original term
"Tampa formation" to include "all sediments lying above the Suwannee
limestone and below the Alum Bluff group." Purl (1953a) erected the
Tampa Stage and included in it "all Miocene sediments lying between the
Oligocene Series and the Alum Bluff Stage." He recognized two lithofa-
cies in the Tampa Stage, an updip, silty and clayey facies (Chattachoo-
chee), and a downdip calcareous facies (St. Marks). Puri and Vernon
(1964) erected the Chattahoochee and St. Marks formations in Wakulla
County, Florida. Puri and Vernon (1964) described the St. Marks Forma-
tion as a "pale, argillaceous, rubbly limestone, in places indurated marl,
with casts of molluscs, Sorites sp. and rounded nodules of limestone"
overlying "a hard, yellowish-gray, massive limestone, with casts and
molds of molluscs." In Leon County, however, the St. Marks Formation is
"predominantly fine to medium-grained, partly crystallized, silty to
sandy limestone" (Hendry and Sproul, 1966). Yon (1966) described the
St. Marks Formation in Jefferson County as a "white to very pale
orange, finely crystalline, sandy, silty, clayey limestone." Colton (1978)
and Ceryak et al. (1983) described the St. Marks Formation in the Upper
Suwannee River Basin as a pale orange to yellow, sandy, silty, micritic
limestone.

Hawthorn Formation

Dall and Harris (1892) first used the term "Hawthorne beds," referring
to phosphatic limestones and clays containing silicified marine fossils
exposed in mines near Hawthorne, Florida. Matson and Clapp (1909)
designated these beds as the Hawthorne Formation which they placed
into the Apalachicola Group, along with the Chattahoochee and Tampa
formations. Vaughan and Cooke (1914) recommended that the name
Hawthorne be discarded because of the overwhelming similarities of the
Hawthorne Formation sediments to those of the Alum Bluff Formation as
defined by Matson and Clapp (1909).
After Gardner (1926) raised the Alum Bluff to group status in the
Florida panhandle, Cooke and Mossom (1929) resurrected the Hawthorn
Formation as part of the Alum Bluff Group, containing Chipola-age fossils
and excluding the older Cassidulus-bearing limestone, i.e., Suwannee
Limestone. Cooke (1945) noted the presence of Hawthorn sediments in
outcrops and mines in north and central Florida. He described the Haw-
thorn as gray and cream-colored, phosphatic sand with lenses of green
or gray Fuller's earth. Pirkle (1956, 1958) discussed the Hawthorn for-
mation in Alachua County and presented measured sections of Brooks
Sink and Devil's Mill Hopper. Puri and Vernon (1964) designated expo-
sures at Brooks Sink in Bradford County, utilizing a section measured by
Pirkle (1956) and at the Devil's Millhopper in Alachua County as co-type
sections. In addition to the sands and clays that Cooke (1945) described,

BUREAU OF GEOLOGY

the cotype sections contain major amounts of phosphatic limestones and
carbonatess." Scott (1982) discussed cotype cores at these localities.
Numerous investigators have divided the Hawthorn Formation into
varying numbers of lithologic units (Carr and Alverson, 1959; Ketner and
McGreevy, 1959; Espenshade and Spencer, 1963; Wright, 1974; Miller,
1978; Reik, 1980; LeRoy, 1981; and others). Although the formation is
generally thought to be Middle Miocene in age, recent studies have indi-
cated that Oligocene and Pliocene sediments may also comprise parts of
the Hawthorn sediments (T. Scott, Fla. Bureau of Geology, personal com-
munication). Scott (1983) reported that "the most common lithologies in
the Hawthorn are dolomitic clayey sands and clayey and/or sandy dolo-
mites." He also noted that much of what had been called clays by pre-
vious investigators were actually clayey dolosilts.
The spelling of the term Hawthorn (Hawthorne) has been controver-
sial. The present use of Hawthorn is based on its acceptance by most
investigators of the unit. For a review of the usage, see Dall and Harris
(1892), Matson and Clapp (1909), Vaughan and Cooke (1914), Cooke
and Mossom (1929), Brodkorb (1963), Puri and Vernon (1964), Williams
et al. (1977), and Scott (1983).

Alachua Formation

The name Alachua clays was designated by Dall and Harris (1892) for
vertebrate bone-bearing beds found "in sinks, gullies and other depres-
sions in the Miocene, Upper Eocene and later rocks of Florida, especially
on the western anticline in higher portions of Alachua County and along
the banks of many rivers and streams." They described the clays as
being "of a bluish or grayish color and extremely tenaceous." Matson
and Clapp (1909) included the Peace Creek bone bed of Dall in the
Alachua clay. Sellards (1910) applied the name "Dunnellon formation"
to hard-rock phosphate beds in the Dunnellon region, but he later
included these deposits in the Alachua formation. Cooke and Mossom
(1929) followed Sellards' expanded usage. Cooke (1945) reported the
occurrence of the Alachua formation from the northern part of Gilchrist
County into Hernando County, with small patches in Lafayette, Hamil-
ton, Alachua, and Marion counties, although details of the locations were
not included. Cooke described the formation as "merely the collapsed
and compacted residue of the Hawthorn formation in situ together with
accumulations in sinkholes and ponds." Vernon (1951) and Puri and
Vernon (1964) described the Alachua formation as "terrestrial, in part
possibly lacustrine and fluviatile, and as a mixture of interbedded irregu-
lar deposits of clay, sand and sandy clay of the most diverse characteris-
tic," with concentrations of vertebrate fossils from Early Miocene to
Pleistocene located sporadically in the sediments. Vernon (1951)
believed the formation "to be in part contemporaneous with the Haw-
thorn formation and in part of younger age." Pirkle (1956) questioned
the value of the Alachua Formation as a stratigraphic unit in his discus-

REPORT OF INVESTIGATION NO. 96

sion of the problems incurred by those attempting to use the unit. Meyer
(1962) noted the occurrence of the Alachua (?) Formation in south-
central Columbia County, but included it in the Hawthorn Formation on
all his cross-sections. Yon and Puri (1962) and Purl et al. (1967) dis-
cussed the occurrence of the Alachua Formation in Gilchrist County.
Clark et al. (1964) noted the occurrence of the Alachua formation in
southwestern Alachua County where it forms low hills of sand, sandy
clays, and clays. In their study of western Alachua County, Williams et
al. (1977) described the principal component of the Alachua formation as
a "faintly stratified and cross-bedded, light gray to bluish-gray, clayey,
phosphatic sand which weathers red to orange and is coherent but rarely
well indurated." Minor amounts of hard-rock phosphate underlying or
interbedded with phosphatic, clayey sands were also noted. Colton
(1978) reported that Dr. Thomas H. Patton of the Florida State Museum
did not consider the Alachua sediments to constitute a true formation,
but rather considered it a "grab bag" term applied to all deposits of
similar nature formed by recurrent karst processes active in Florida since
at least Oligocene time. Colton could not differentiate Alachua-type sedi-
ments from Hawthorn sediments in Hamilton County. Ceryak et al.
(1983) could not differentiate the lithologies of the Alachua Formation
from either the Hawthorn Formation or the Undifferentiated Terrace
Deposits in either outcrop or subsurface sections.

Stratigraphic Nomenclature:
Problems and Usage in This Study

As one attempts to define and delineate the Cenozoic stratigraphy of
an area in Florida, it is evident that many of the formations historically in
use in Florida have no distinguishing lithologic characteristics. Unfortu-
nately, most of the classification of Florida's rock units occurred before
the present Code of Stratigraphic Nomenclature (American Commission
on Stratigraphic Nomenclature, 1961), governing the use of stratigraphic
terminology and classification, was adopted. The Florida Commission on
Stratigraphic Nomenclature was organized to revise the stratigraphic
units defined prior to 1961 in order to achieve conformity with the Code
(Randazzo, 1976). Unfortunately, the commission was disbanded before
the revision could be achieved, thus leaving many significant nomencla-
tural problems unsolved.
Most of the formational names in Florida were erected by paleontolo-
gists. Thus, many of the formations in use are actually biostratigraphic
units defined on the basis of faunal associations or first occurrences of
particular species of microfossils.
The Cedar Keys Formation of Cole (1944) (uppermost occurrence of
Borelis spp. to the top of the Cretaceous [determined by the occurrence
of certain foraminifera]), the Oldsmar Limestone of Applin and Applin
(1944) (uppermost occurrence of Dictyoconus americanus to the top of
the Oldsmar Limestone [defined biostratigraphically]), and the Avon Park

BUREAU OF GEOLOGY

Limestone of Applin and Applin (1944) (uppermost occurrence of Dic-
tyoconus cookei and other distinct fauna to the top of the Lake City
Limestone Ibiostratigraphically defined]) are all biostratigraphic units.
Lithologically, these "formations" are generally indistinguishable from
each other. Vernon (1951) stated that these formations, the Cedar Keys
Formation, the Oldsmar Limestone, and the Lake City Limestone are not
lithologically distinguishable. Chen (1965) reported that the Oldsmar
Limestone was not lithologically different from the Lake City Limestone.
Banks (1976) combined the Avon Park Limestone and the Lake City
Limestone into one unit on the basis of similar lithology.
Chen (1965) and Vernon (1951), to some extent, attempted to estab-
lish lithologic criteria for the formations through establishment of litho-
logic marker beds. Two problems arose with the attempt to find lithologic
criteria for biostratigraphically-defined formational units: 1) often,
boundaries of the lithostratigraphically-defined unit did not correspond to
the boundaries of the biostratigraphically-defined unit, and 2) the litho-
logic marker beds were discontinuous or changed their lithology laterally
from well to well. Currently, some investigators pick formational bounda-
ries using biostratigraphic criteria while others have established non-
standardized, lithologic criteria. It is evident that, although the two
groups are using the same formational name, they may not be applying
the term to the same strata.
Similar problems resulted from numerous classifications of the Ocala
Limestone sediments. Applin and Applin (1944) separated the Ocala
Limestone into upper and lower members on the basis of lithology and
fauna. Vernon (1951) divided the Ocala Limestone into two formations,
the Ocala Limestone (restricted) and the Moodys Branch Formation. He
divided the Moodys Branch Formation into two members, the Williston
and the Inglis. He made these separations on the basis of subtle lithologic
differences and faunal considerations, e.g., the first occurrence of
Amphistegina pinarensis cosdeni designating the top of the Williston
member. Evidently, Vernon had some misgivings about where to draw
his boundaries. He stated that "the Williston member is a transition bed
of limestone that is closer lithologically to the Inglis member than to the
Ocala limestone." Then Vernon states, "Probably as much argument
could be presented that the bed is a member of the Ocala (restricted) as
could be cited in support of placing it in the Moodys Branch Formation."
Vernon further states, "Both the fauna and lithology of the Williston
grade into the Ocala Limestone and an exact contact can rarely be
placed."
Puri (1957), using the rock descriptions and outcrop data that caused
Vernon (1951) some misgivings, established his reclassification of the
Ocala Limestone, divided the section corresponding to Vernon's Ocala
Limestone (restricted) and the Williston and Inglis members of the
Moodys Branch Formation into three formations (the Crystal River For-
mation, the Williston Formation, and the Inglis Formation) and placed
these three formations in the Ocala Group. Puri established these forma-

REPORT OF INVESTIGATION NO. 96

tional units on the basis of biostratigraphic differences. Lithologic
descriptions of the type sections, however, do not show any marked
differences among the three units. Cole and Applin (1964) recommended
that the Inglis Formation be abandoned since the index fauna, in addition
to the lithology, were continuous into the underlying Avon Park Forma-
tion.
A severe problem encountered when formational picks are made on
the basis of biostratigraphy, in addition to the problem that the formation
thus defined may not correspond to the formation defined by lithologic
criteria, is that where the microfossils are missing, destroyed, or poorly
preserved, the worker cannot determine the formational boundaries.
Additionally, picks based on the use of microfossils require use of micro-
scopes, which is very inconvenient for field identification.
Unfortunately, in Florida, the problems and conflicts discussed above
have not yet been resolved. In order not to confuse the literature further,
this study will not divide the strata underlying the Suwannee Limestone
into individual formations. The Ocala Group Undifferentiated will be used
since the section thus defined corresponds closely to both the Ocala
Group of Puri (1957) and the Ocala Limestone of Cooke (1915) and
Applin and Applin (1944). The underlying strata usually divided into the
Avon Park Limestone, the Lake City Limestone, and the Oldsmar Lime-
stone will be differentiated into two major lithofacies: the dolomite litho-
facies (DF) and the undifferentiated carbonate lithofacies (UCF). The lack
of agreement on the lithologic basis of these formations, as well as the
limited number of wells drilled into these deeper strata and the very
discontinuous nature of the samples collected from these wells, justify
the decision to eliminate formational picks in these strata. The forma-
tions that overlie the Ocala Group Undifferentiated, the Suwannee Lime-
stone, the St. Marks Formation, and the Hawthorn Formation can be
differentiated on the basis of lithology. Since there is much disagreement
as to whether the Alachua sediments constitute a true formation (Pirkle,
1956), they are termed the "Alachua (?) Formation" in this study. No
attempt has been made to differentiate the sediments (sands, sandy
clays, clayey sands, and clays) which overlie the above-mentioned litho-
logic units.

Geology of the Lower Suwannee River Basin
Previous Investigations

Our knowledge of the geology of the counties included in the Lower
Suwannee River Basin has mostly been pioneered by Cooke (1945), who
made some observations on the geology of these counties in his Geology
of Florida. Previously, short summaries of the geology of the counties
based on outcrop information were included in general reports on the
geology of Florida by Matson and Clapp (1909) and Cooke and Mossom
(1929). Applin and Applin (1944) included the study area in the geo-
graphic scope of their study on the regional subsurface stratigraphy of

BUREAU OF GEOLOGY

Florida and southern Georgia in which they mapped the Lower Creta-
ceous to Oligocene strata. Vernon (1951) published a comprehensive
study of Citrus and Levy counties which included discussion of the phys-
iography, structure, stratigraphy, and economic geology of the area. Sim-
ilar studies were published for Columbia County by Meyer (1962) and for
Dixie and Gilchrist counties by Puri et al. (1967).
Puri (1957) examined wells and outcrops in the study area in conjunc-
tion with his zonation of the Ocala Group. Yon and Puri (1962) reported
on the geology of the Waccasassa Flats in Gilchrist County. Chen (1965)
included the study area in his regional lithostratigraphic analysis of Paleo-
cene and Eocene rocks of Florida. Numerous master's theses and related
reports prepared at the University of Florida reported on the lithostrati-
graphy and geochemical analyses of several cores collected in Citrus,
Levy, Dixie, and Gilchrist counties (Hickey, 1976; Randazzo, 1976; Sar-
ver, 1978; Zachos, 1978; Fenk, 1979; Metrin, 1979; Randazzo, 1980).
Knapp (1978a; 1978b) presented several stratigraphic cross-sections
transecting the study area in conjunction with his Valdosta and Gaines-
ville quadrangle environmental maps. The geology of areas adjacent to
the Lower Suwannee River Basin was discussed in studies of the Upper
Suwannee River Basin (Ceryak et al., 1977); of Alachua, Bradford, Clay,
and Union counties (Clark et al., 1964); and of the Coastal Basin to the
west of the Suwannee River Basin (Copeland and Burnson, in press).
Knapp (1978a; 1978b) published maps depicting the surficial geology of
the basin area (Figure 8).

Methods of Investigation and Data Collection

This present study is based on subsurface information from the analy-
sis of cuttings from water and oil wells and cores from stratigraphic test
wells. These well cuttings and cores are stored at the Florida Bureau of
Geology in Tallahassee, Florida. In all, 222 sets of well cuttings, 67 sets
of auger samples, and six cores were examined for this study.
The cuttings and cores were examined with a binocular microscope,
and a standardized data sheet was filled out for each well, with such
parameters as dominant rock type, color, porosity type and percentage,
grain-type, grain-size, induration, cement type, sedimentary structures,
degree of recrystallization, accessory minerals, fossils present, and
depth of sample recorded. Alizarin Red S and dilute HCI solutions were
used to aid in the identification of calcite and dolomite, and an ammo-
nium molybdate solution was used to test for the presence of phosphate.
Data from these analyses were utilized in the construction of strati-
graphic cross-sections, lithostratigraphic unit-thickness maps, top-of-
structural-units maps, and a structure-contour map.

REPORT OF INVESTIGATION NO. 96

2o-oo' +

0 5_ 10 KM
0 5 10 20 OKM

EXPLANATION
MCLAYEY SAND
SAND
II LIMESTONE
P DOLOMITE
LIMESTONE /DOLOMITE

Figure 8. Distribution of surficial sediments (having a thickness greater
than 10 feet) in the Lower Suwannee River Basin (outlined in
black) and vicinity (after Knapp, 1978, 1978b).

BUREAU OF GEOLOGY

Stratigraphy

The discussion of the lithostratigraphy of the study area is graphically
supplemented through the use of three north-to-south geologic cross-
sections (Figures 9-15), 15 west-to-east cross-sections (Figures
16 28), unit-thickness maps, top-of-unit maps, and a structure-contour
map. Additional data and detailed lithologic descriptions of selected well
samples are provided in Appendices I and II. The maximum depth to
which lithologic samples were described for any well was 1200 feet due
to hydrogeologic considerations which will be discussed in a later sec-
tion. The discontinuous nature of well cuttings and the numerous large
gaps in the available stratigraphic data necessitate a more general dis-
cussion of lithologies and preclude detailed correlation schemes. The unit
thickness maps are utilized instead of isopach maps and top of unit maps
are used instead of structure-contour maps with one exception, a
structure-contour map of the top of the Dolomite Lithofacies (DF). The
karstic nature of the terrain precludes the construction of meaningful
contour patterns, particularly for the Ocala Group, the Suwannee Lime-
stone, and the overlying undifferentiated sands and clays. The random
distribution of sinks and other solution features, the discontinuous
nature of these strata, and the lack of adequate well coverage required
for detailed work in a karst region dictate the utilization of a more gener-
alized mapping technique.

Undifferentiated Carbonate Lithofacies (UCF)

The Undifferentiated Carbonate Lithofacies consist of three lithologic
types, dolomite, limestone, and mixed carbonates and evaporites. The
dolomite is light-olive gray to yellow-gray to dusky yellow, sucrosic,
medium to well-indurated, with crystals ranging in size from less than
0.062 mm to 0.5 mm. Peat is sometimes distributed in the dolomite in
seams or as peat flecks; infrequently, chert or clay mineral layers are
found in the dolomite. Occasionally, foraminiferal, bryozoan and mollus-
can fragments, and fossil molds are present but usually the dolomitiza-
tion process has eradicated the fossil traces.
The limestones are of three general types, calcilutite, calcarenite, and
calcirudites. The calcilutite is very light gray to yellowish-gray, moder-
ately to well-indurated, often dolomitic, frequently with golden-brown
calcite or dolomite rhombs in the matrix, occasionally with foraminiferal,
bryozoan and molluscan fragments, and fossil molds. The calcarenite is
very light gray to yellowish-gray, very fine to coarse-grained, skeletal,
moderately to well-indurated, occasionally dolomitic, with miliolid and
other foraminifera, frequently Dictyoconus americanus, and fossil molds.
The calcirudite is very light gray to light olive-gray, granule-grained, skel-
etal, moderately to well-indurated, often dolomitic, with miliolid and
other foraminifera, frequently Dictyoconus americanus, and molluscan
and other fossil fragments.

REPORT OF INVESTIGATION NO. 96

0ooo'0 -

DX

L

( t_ I MI ,l
0 S 10 20 KM

EXPLANATION
A WELLS NOT USED
FOR N-S OR W-E
CROSS-SECTIONS

WELLS USED FOR
N-S CROSS-SECTIONS

+ 30 00'

T6S

T S

T8S

T9S

T OS

T115
+A l* 50'

T 2S

TISS

+ IwI"

Figure 9. Map showing 1) locations of wells used to construct north-
south geologic cross-sections, and 2) locations of wells not
used on cross-sections, but used in the construction of other
geologic figures.

-- II I I 'I I- I I --

Figure 10. Geologic cross-section A -A'. Location shown on Figure 9.

I A' A"
I 0159S d W-
,40" AL U. l

SOG .~~OM ----
4 0 0 M5O OCALA _.D

'35 G Bo OCA 2
*I O In
M0 OOM F M IA E "

.oo DFP DO E DF DFAC

-300 LS-- -L ME

-3500 EXPLANATION Z
.---" "S SAND, SANDY GLAY CLAY
,LS OGU OCALA GROUP UNDIP Z
-400 20 L OMF OCALA MILIOLID FACES
I g UCF 1 UCF OF DOLOMITE FACES o
UCF UNIF, CARBONATE FACIES
-M00 M-GK DL
200 g cs-s o A LD DOOMeITE 9
WIK M KD
-no.2 a M j M MIXED CARBONATED ')
- Ko M: M G GYPSUM
-Ro G'M,, K -G K GLAUCONITE
S u ,K W WELL.CUTTINGS
"1000 .0 AS AUGER SAMPLES
.100 0. MILE

Figure 1. Geologic cross-section A'-A". I.ocation shown on Figure 9,

9

B B

40

mo o
*0
to

0"80
-SO
-60

.400 *
-410

.too

-1200 .60

Figure 12.

OGU ----

OF
---" 3

I-- DF

1
M M j

EXPLANATION
S SAND, SANDY CLAY, CLAY
H HAWTHORN FORMATION UCF
SM ST. MARKS FORMATION
SW SUWANNEE LIMESTONE
OGU OCALA GROUP UNDI.
DF DOLOMITE FACIES
U UNDIF. CARBONATE FACES
L DOLOMITE
K L LIMESTONE M-GK
L M MIXED CARBONATES M K,G ,
a GYPSUM mJ
K GLAUCONITE
G W WELL, CUTTINGS o0

Cross-section B-B'. Location shown on Figure 9.

JJ UCF

fIIrrT rniL~otets

B' B"

ISO,

*.0. -. OGU I 0OMF .,, ." EXPL ANATION4 "

I--II '1/ / \ DF S SAND,SANDY CLAY CLAY .a
.0 I / \ OGU OAL GROUP UNDIF.
I /D' \, OMF OCALA MILIOLID FACIES
I40 "\ DF DOLOMITE FACIES G)
Io OF U UNDIF CARBONATE FACIES
/ 0 O DOLOMITE

,\ W IWELLCUTTINGS .
.250 -- \ AUGEA SAMPLES

-,, ,,I, ,- .C F P-. ,, P
-o U F UC KILFMI

-1.60 0
-600

Figure 13. Geologic cross-section B'- B". Location shown on Figure 9.

go
40 W-3

o OGU

*iaseDF SA s SNo m
00 '0 m

DF 0S SANDY CLAY, CLAY
SHAWTHORN FORMATION
'-, D. SW SUWANNEE LIMESTONE rC
OGU OCALA GROUP UNDIE
ODF DOLOMITE FAECIS0
UCF UNDIF CARBONATE FAC4,S G
-D DOLOMITE
"3o. LS .LS LIMESTONE
M MIXED CARBONATES
-so 0 GYPSUM
-400-120 D W WELL,CUTTINGS

-0oo0 UCF

Figure 14. Geologic cross-section C
.20

-1200 *36 0

Figure 14. Geologic cross-section C -C'. Location shown on Figure 9.

200 60

20 *o
50 mo

S.5OGU OGU /OGU OG

4 EXPLANATION
-o SAND SANDY CLAY CAY
SoA ALAocuA FORMATIbN mI
OrU OCALA GROUP UNDIE en
-2 -.60 F OMF OCALA MILIOLID FACES
20 DOLOMITE FACIES
-. Cu. o.F UNDI. CARBONATE FACES
-250,IDOLOMITE G)
o LS LIMESTONE
M MIXED CARBONATES
0LS G GYPSUM S
-0 W WELL,CUTTINGS

-g 0 UCF o C
W L SL

*1 520 *38> -G -G
Figure 15. Geologic cross-section C' ". Location shown on Figure 9.

Figure 15. Geologic cross-section C'- C". Location shown on Figure 9.

BUREAU OF GEOLOGY

.,v *yoo' *y,
+ +
R9 RIOE RIlE RI2E R3E R14E 'RISE RISE RITE

TIS

T2S
TAYLOR C LAFAETTE

-E EC N K-- TSS

WELL USED OGG TIS
NONE

EIS
f l I I \ S

WELLSUSED FOR TSs

geologic cross-sections.
Y^I _j^^

Fgure NAQ 16. Map shwn octosofwlsusdt ontutwetes
geologic cosetin.yg--.^. -- ^- ----

40

II wo i

S" \0 \\. \\ .

SaW

o I 0G U W-2590

-,o ,- OGU "O

----- OGU ---- --- OGU

-a eo -cF DF '

-300. DF "S"...

. 2 00- 60 s
.10 UCF UCF D UCF
- 100 -0 S LS M
-L -

- 1 .0 a. |L S -

*120o0 6

Figure 17. Geologic cross-section D D'. Location shown on Figure 16.

EXPLANATION
S SAND SANDY CLAY CLAY
H HAWTHORN FORMATION
SM ST. MARKS FORMATION
SW SUWANNEE LIMESTONE
OGU OCALA GROUP UNDIF
DF DOLOMITE FACIES
UCF UNDIF. CARBONATE FACES
D DOLOMITE
LS LIMESTONE
MIXED CARBONATES
G GYPSUM
K GLAUCONITE
W WELL,CUTTINGS
We WELL,CORE
1 j, I i MILIS
S II KILOIITINS

0'S
5 I 1 SW SW/

S OGU\
01. oI OGU m

-------------o--- OGU

.oo o --------- ---------.....- -.-- --.. ......-- ...- .)
9O

.0 4 O
-0 FF 01

,o --T--', oF 0
SODF EXPLANATION -
00 SAND SANDY CLAYAY
LS H HAWT IIN FORMATION
0 SM IT MARKS FORMATION
*8B SW SUWANNEE LIMESTONE
S" OGU OCALA GROUP UNDIF.
M OF DOLOMITE FACES
- *120 T UCF UNDIF CARBONATE FACIES
1 UCF M DOLOMITE
B0 I LS LIMESTONE
-600 a LJ M MIXED CARBONATES
00aO UF LS -K,D 6 GYPSUM
SG DK GLAUCONITE
o00 *40 DW WELL, CUTTINGS
a Iit rE AS AUGER SAMPLES
*i80 i -G
3 LSI-K
*.1200 3s

Figure 18. Geologic cross-section E- E'. Location shown on Figure 16.

200o 60

ISO10
40
100
20
SO
50.

0o

.20

-100
-150

-e40

.1 -.0
-Fooi e

-1000

Figure

UGF LS

D

Geologic cross-section F F'. Location shown on Figure 16.

H S n
\ s m

0
I
OGU

EXPLANATION 0
S SAND, SANDY CLAY, CLAY Z
H HAWTHORN FORMATION
SW SUWANNEE LIMESTONE Z
OGU OCALA GROUP UNDIF.
OF DOLOMITE FACES 0
UCF UNDIF. CARBONATE FACES
0 DOLOMITE
LS LIMESTONE
6 GYPSUM
K GLAUCONITE
W WELL, CUTTINGS

19.

ILI _u r.CS
o11.aut1itill frH

EXPLANATION
UF LS S SAND, SANDY CLAY, CLAY
UGF L UCF SW SUWANNEE LIMESTONE
OGU OCALA GROUP UNDIF
SKD, OF DOLOMITE FACIES
D-K UCF UNDIF. CARBONATE FACES
0 DOLOMITE
D= LS LIMESTONE
M MIXED CARBONATES
SLS3-K M.. GYPSUM
LS M-K G K GLAUCONITE
LS W WELL, CUTTINGS

i i L s o F IL6.

Geologic cross-section G G'. Location shown on Figure 16.

60
40

60.1

*0

*ISO

400

*0oo
*100
*350

.400, t 120

-20
*B r -2402
3000 -20

.1200 *03640

Figure 20.

150
40
100"

50

0-0

-50
-00
-00

*40

-300
"300
-3SO0

Geologic cross-section H H'. Location shown on Figure 16.

EXPLANATION
S SAND. SANDY CLAY CLAY
SW SUWANNEE LIMESTONE
OGU OCALA GROUP UNOIF.
OF DOLOMITE FACIES
UCF UNDIR CARBONATE FACIES
D DOLOMITE
LS LIMESTONE
M MIXED CARBONATES
6 GYPSUM
K GLAUCONITE
W WELL CUTTINGS
AS AUGER SAMPLES

010 I 3 B MILIS

*-400 120 CD
S eo -
o ..ol
r"00
-6o. -240

-1200 *4D

Figure 21.

BUREAU OF GEOLOGY

EXPLANATION
S SAND, SANDY CLAY CLAY
SW SUWANNEE LIMESTONE
OGU OCALA GROUP UNDIF
DF DOLOMITE FACIES
UCF UNDIF. CARBONATE FACIES
D DOLOMITE
LS LIMESTONE
M MIXED CARBONATES
G GYPSUM.
K GLAUCONITE
W WELL.CUTTINGS

uti- UCF

I-
M---GK LS3~'
0 1 a 3 4 5 6 XIMIT1 ES

EXPLANATION
S SAND, SANDY CLAY CLAY
OGU OCALA GROUP UNDIF
DF DOLOMITE FACIES
UCF UNDIF. CARBONATE FACIES
D DOLOMITE
LS LIMESTONE
M MIXED CARBONATES
G GYPSUM
K GLAUCONITE
W WELL CUTTINGS
AS AUGER SAMPLES

Figure 22. Geologic cross-sections I -I' and J -J'. Locations shown on

Figure 16.

46

I ,

ZYo

DF

I
I
I

----------------- --

F o 1 .E
0 234UILOETERS

M WGK

-120.
-no g

-280

-240 i

41KM

50"

-0o OGU -OU OGU OGU-'
4-0
.20 LI
loo00 r
-40 M UCF
*1" L EXPLANATION
5 SANDSANDY CLAY ,CLAY
.200 -60 OGU OCALA GROUP UNDIF,
DF DOLOMITE FACES
UCF UNDIF. CARBONATE FACIES
-250 D DOLOMITE
-80 DF LS LIMESTONE
so M MIXED CARBONATES
.3o. UCF 6 GYPSUM
K GLAUCONITE
o100 W WELL CUTTINGS
.-3. AS AUGER SAMPLES

-ISO jW
-00 l --DLS:

-emo -240 S UCF m
-600

.320 =LS-KG
-100 50 LS-K,G O

00. -360

Figure 23. Geologic cross-section K K'. Location shown on Figure 16.

30 S

50

go C
*I 0 000

DF DF DF 0

EXPLANATION 0
-50s S SAND,SANDY CLAY, CLAY Im
-so A "ALACHUA FORMATION" 0
OGU OCALA GROUP UNDIF
*o. S OMF OCALA MILIOLIO FACES I
1oo UCF UNDIF. CARBONATE FACIES
*3o 0 D DOLOMITE
-- ----------- LS LIMESTONE NT
-200--,-- L --S -- - -S M MIXED CARBONATES
-400 o. *1 CG GYPSUM
SK GLAUCONITE
-1o0 UCF W WELL CUTTINGS
.600. 1 m -GK AS AUG E SAMPLES
..g-o00 UC M",K We WELL, CORE
.* em. 240 4 T 1TTTsi LOMETIlD

-1000 2

.1200.3O0- O 0

Figure 24. Geologic cross-section L L'. Location shown on Figure 16.

M M'

mr
t -o- W-1 9 7 W. .
20

.20 I ------ -
-.20
SI00 m
DF DF EXPLANATION
S SAND SANDY CLAY, 0CAY G)
DF A "ALACHUA FORMATION
.-200-60 OGU OCALA GROUP UNDIF,
OMF OCALA MILIOLID FACES
DF DOLOMITE FACIES
-2S. UCF UNDIF, CARBONATE FACIES 0
-o M MIXED CARBONATES
W WELL, CUTTINGS
-300 AS AUGER SAMPLES

*-0- -- -------------?- ------------ -- -- P
UCF
F Oi u 21 3 4 G ca KILOMTIN1

Figure 25. Geologic cross-section M-M'. Location shown on Figure 16.

BUREAU OF GEOLOGY

EXPLANATION
S SAND, SANDY CLAY, CLAY
OGU OCALA GROUP UNDIF
OMF OCALA MILIOLID FACIES
OF DOLOMITE FACIES
UCF UNDIE CARBONATE FACES
LS LIMESTONE
M MIXED CARBONATES
G GYPSUM
W WELL.CUTTINGS
AS AUGER SAMPLES

-ca,

-340 1 M
-t"0

Geologic cross-section
Figure 16.

N-N'. Location shown on

The mixed lithologies include the dolomite and limestone lithologies,
described above, interbedded in thin alternating beds. In wells that pene-
trate the lower part of the UCF strata, gypsum in thin layers and in
interstitial spaces was noted in both dolomite and limestone units.
Glauconite, disseminated in limestone and dolomite units, was also
noted in these deeper strata. The first noted occurrences of gypsum and
glauconite are indicated on the cross sections. Obviously, where a gap
exists in the section, the first occurrence could be higher in the section,
i.e., in the gap.

Dolomite Lithofacies (DF)

The dolomite of this lithofacies is yellow-gray to light olive-gray or
moderate olive-brown to olive-gray, sucrosic, poorly to well-indurated,
with subhedral crystals ranging in size from less than 0.062 mm to 0.5
mm. The dolomite is occasionally peat-flecked; occasionally it contains
fossil molds and foraminiferal, molluscan, and bryozoan fragments. Usu-
ally, most of the fossils have been obliterated by dolomitization. Proc-
esses responsible for this dolomitization are discussed in Back and Han-
shaw (1970) and Hanshaw and Back (1979). Infrequently, thin beds of a

Figui

re 26.

0 1 2 3 4MES
0 1 2 3436ILOMETERS

0 P P'

W1 ...5 ] soi 4 A 1

W 1 EXPLANATION A
S..o. S SAND, SANDY CLAY, CLAY
S-so

-50 ou OCALA GROUP UNDIF.

EXPLANATION -00 UF UNIF. CARBONATE FACES UC
SS SAND- SANDY CLAY, CLAY --a DOLOMI

-0o0 O M ADOMIXED CARBONATES -I0 DL I T
os
I -------- OF D ID

-0 K GLAUCONITE 0CF "0

M C CHERT )
-800 -240 W LL, CUTTINGS
-280 AS AUGIER SAMPLES ACL
Fi r 2N7F OCALA MILIOLID FACIESiL on
U A SN C Y L M UCF UN,. RO CARBONATE FACES

-1000 ,Lo OCA LA G U LS, D DOLOMITE .r

FF DOLOMITE FACES 00 n AE L o
F ig ,120' DO lo c s ti 0 -00 1. 5
,-10 M MIXED CARBONATES ,.-K -.0 p
2-0 K GLAUCONITE --G F
.800. 0 w WWELL CUTTINGS
so's AUGER SAMPLES

Figure 27. Geologic cross-sections O-O' and P-P'. Locations shown on Figure 16.

00
to

40 -

EXPLANATION
S SAND SANDY CLAY CLAY
OGU OCALA GROUP UNDIF.
OMF OCALA MILIOLID FACIES
OF DOLOMITE FACIES
UCF UNDIF. CARBONATE FACIES
LS LIMESTONE
W WELL CUTTINGS
AS AUGER SAMPLES
,1 ; .I LO T IIl

R'

W-1846

R

^fYi9 I

S OGU .--. -
oCU/--

-40
-Io

I

E-o15

OGU

+

DF oa
Oh

-. t-
UCF

DD

EXPLANATION
S SAND SANDY CLAY CLAY
U OCALA GROUP UNDIF
IF OCALA MILIOLID FACES
F DOLOMITE FACIES
F UNDIF, CARBONATE FACES
D DOLOMITE
S LIMESTONE
W WELL CUTTINGS
S AUGER SAMPLES
1__6_"j "LHU
. .. II I.t.'LO TiRS

Figure 28. Geologic cross-sections Q-Q' and R-R'. Locations shown on Figure 16.

1 I I I

I

I

REPORT OF INVESTIGATION NO. 96

very light gray to yellow-gray, medium-grained, skeletal calcarenite,
medium to well-indurated, with miliolid and other foraminifera and fossil
fragments, are found interbedded in the dolomite unit.
This unit ranges in thickness from approximately 25 feet to 300 feet.
No discernible trends are evident in the thickness of the unit throughout
the study area. The top of the unit deepens to the northeast and north-
west borders of the study area while achieving its highest elevation along
the Suwannee River in the central portion of the study area (Figure 29).
Two minor higher areas are shown in the southern end of the study area.
The top of the unit ranges from 38 feet below land surface near the
mouth of the Suwannee River to 445 feet below land surface in the
northeast corner of the study area. This trend is related to the thickness
of overlying strata that form the uplands in the northern portions of the
basin since the dolomite unit itself is rather flat-lying, the relief of the top
of the unit is less than 100 feet in much of the basin.

Ocala Group Undifferentiated

The Ocala Group Undifferentiated (OGU) contains three types of
marine limestone that grade into each other. The transitional lithologic
units are often thicker than the more distinctive lithologic end-point
units. The deepest lithology is a very light gray to light olive-gray, very
porous, medium-grained, skeletal calcarenite, medium to well-indurated,
composed almost entirely of miliolid foraminifera; this lithology has been
named the miliolid lithofacies (OMF) of the Ocala Group (OGU). This
lithology grades upward into a white to pale-yellowish orange, medium
to very coarse-grained, skeletal calcarenite, medium to well-indurated,
composed of foraminifera, particularly Operculinoides sp. and miliolids.
This lithology then grades upward into a white to very pale orange,
porous, coarse calcarenite to fine calcirudite, skeletal, poorly to moder-
ately indurated, composed of the remains of large foraminifera, particu-
larly Lepidocyclina sp., set in a chalky-appearing matrix of micrite or
microspar.
The OGU ranges in thickness from approximately 10 feet to 245 feet
(Figure 30). Many of the greater thicknesses are located in the northeast-
ern portion of the basin, while the thinner strata are found along the
course of the Suwannee River. The thinner OGU strata generally lie in
areas where the underlying Dolomite Lithofacies form topographic highs.
The elevation of the top of this unit ranges from 110 feet NGVD to 71
feet NGVD (Figure 31). The highest elevations generally are observed in
the northern portion of the basin; however, the lowest elevations also
occur in this area, in both the northeast and northwest corners of the
basin. Lower elevations are also observed along the southern portion of
the Lower Suwannee River. The lowest elevations coincide with the
lowest elevations of the underlying Dolomite Lithofacies unit. The top of
much of the Ocala Group Undifferentiated lies between one and 49 feet
NGVD, with most of the variation due to formation of karst features,

BUREAU OF GEOLOGY

3 5 1 Mt
a 5 C 2 KM

50 Ft CONTOUR INTERVALS
MEAN SEA LEVEL 0 Ft.
DEPTH TO UNIT AT
WELL LOCATION
+ PRESENT BUT DEPTH TO
TOP OF UNIT INDETERMINABLE

Figure 29. Structural contour map of the top of the Dolomitic Lithofa-
cies (DF) in the Lower Suwannee River Basin.

+ s0 00

T119S 0
+-29-30.

+ 29-15'

r

REPORT OF INVESTIGATION NO. 96

EXPLANATION

10 Ft. to 49Ft.
50 Ft. to 99 Ft.
100 Ft. to 199 Ft.
200 R. to 245 Ft.
Present, but thickness of
unit indeterminable

Figure 30. Thickness of the Ocala Group Undifferentiated (OGU) in the
Lower Suwannee River Basin.

3000' +

4

o 5 10 MI
0 5 10 20KM

+ 30o 00'
T6S

T7S

TBS

T9S

TIOS

T11S
+29" 30

T12S

T13S

+ 29* 15'

d -- -Is---~c-

BUREAU OF GEOLOGY

30-00 -

R9E RIOE RIIE RI2E RI3E RI4E RISE RISE RI7E

o a ul

a S V 20 KM

EXPLANATION

82*0

S

-s

2S

5S

4S

55

+30 00'

6S

7S

8S

9S

*los

ris

TI3S

+ 29-15

+ Psent, but depth to top
of unit indeterminable

Depth relative to Mean Sea Level
Mean Sea Level OR.

Figure 31. Elevation of the top of the Ocala Group Undifferentiated

(OGU) in the Lower Suwannee River Basin.

I --

REPORT OF INVESTIGATION NO. 96

especially in the southern part of the basin and along the Suwannee
River. Much of the Ocala Group Undifforentiated lies between one and 49
feet NGVD, with most of the variation due to formation of karst features,
especially in the southern part of the basin and along the Suwannee
River. Much of the Ocala Group Undifferentiated in the northern third of
the basin is covered to some degree by the Suwannee Limestone (Figure
32), whereas the OGU limestones are at or near the surface in the south-
ern two-thirds of the basin.

Suwannee Limestone

The Suwannee Limestone consists of several lithologies: (1) a white
to yellowish-gray to very pale orange, medium-grained, very porous,
skeletal calcarenite, medium to well-indurated, composed of echinoid
and molluscan fragments and molds, and foraminifera, particularly Dic-
tyoconus cookei; (2) a white to very pale orange calcilutite, poorly to
moderately indurated, with molluscan molds and echinoid fragments cre-
ating moderately high porosity in some beds; (3) a yellow-gray to dark
yellowish-orange calcilutite, medium to well-indurated, dolomitic, with
occasional molluscan and echinoid fragments; and (4) a dark yellowish-
brown to yellowish-gray to light olive-gray, sucrosic dolomite, moder-
ately to well-indurated, with subhedral crystals ranging from less than
0.062 mm to 0.125 mm. The limestones are often interbedded; the
limestones and the dolomitic limestone generally overlie the dolomite
when all are present in a section. The calcarenite, however, is the pre-
dominant lithofacies of the Suwannee Limestone in the basin.
The Suwannee Limestone ranges in thickness from O to 190 feet, with
the thickest strata in the northeast and northwest corners of the basin
(Figure 32). This unit covers only the northern third of the basin and is
marked by solution features associated with karst terrains. The unit is
discontinuous in thickness and areal extent.
Where the unit is present, the elevation of the top of the Suwannee
Limestone generally ranges between 50 and 99 feet NGVD, with topo-
graphic highs occurring in the extreme northwest corner and near Live
Oak (Figure 33). The lowest elevations of the top of the unit are found in
southeast Madison County and near the junction of the Santa Fe and
Suwannee rivers. The relief of the top of the unit is a maximum of 160
feet.

St. Marks Formation

The St. Marks Formation in the basin consists of a white to light gray
to yellowish-gray to very pale orange calcilutite, poorly to well-indurated,
with 10 to 35 percent very fine to fine quartz sand and occasional fossil
fragments. This formation was identified in only three wells, where it
rests on the Suwannee Limestone. The St. Marks ranges in thickness

BUREAU OF GEOLOGY

3o0o4 +

S 10 20o M

EXPLANATION

SOR.
IFt.to49Ft
A 50R.to99Ft
SOOFtR.to 9OR.
+ Present, but thickness of
formation indeterminable
- - Limits of Suwannee Limestone

Figure 32. Thickness of the Suwannee Limestone in the Lower Suwan-
nee River Basin.

o

REPORT OF INVESTIGATION NO. 96

@r+

sooo' +

2 O o MI
0 5 10 0 KM

EXPLANATION
0 -35Ft.toORFt.
A Ft. to49F
A 50 R. to 99 Ft.
S100 R. to 125 R.
+ Suwannee Limestone
presentbut depth to top
of formation indeterminable
O Suwannee Limestone Not present
- - Limits of Suwannee Limestone
(sM) St. Marks Formation Present

Figure 33. Elevation of the top of the Suwannee Limestone in the
Lower Suwannee River Basin.

BUREAU OF GEOLOGY

from 50 to 90 feet in these wells and the top of the unit ranges in
elevation from 105 to 115 feet NGVD.

Hawthorn Formation--"Alachua Formation" Residuum

The Hawthorn Formation residuum is generally a yellowish-gray to
light gray, clayey, very fine quartz sand, poorly to moderately indurated,
with 5 to 35 percent phosphatic sand. This lithology is interbedded with
a greenish-gray, sandy clay, with up to 15 percent fine quartz sand and
up to 7 percent phosphatic sand. In one well (W-13008), the lithology is
a light gray to very pale orange dolomitic calcilutite, moderately to well-
indurated, with up to 25 percent fine quartz sand and up to 15 percent
phosphatic sand. The unit ranges in thickness from 0 to 85 feet in the
basin. It is variable in thickness and discontinuous in areal extent and is
found only in the extreme northern and northeastern portions of the
basin (Figure 34). The Hawthorn Formation increases rapidly in thickness
toward Lake City and White Springs, to 167 feet or more, adding lime-
stone and dolomite beds to the sand and clay units (Miller, 1978).
The "Alachua Formation" residuum consists of a white to yellowish-
gray, phosphatic clay, poorly indurated, occasionally with up to 30 per-
cent quartz sand and up to 5 percent phosphatic sand. The clay is occa-
sionally well-indurated, forming a blue-gray, hard-rock phosphate. A
blue-gray or blue-green, greasy clay is also found interbedded with the
white, phosphatic clay. The thickness of the unit is indeterminable, but it
is less than 50 feet. It is thin-bedded and really discontinuous; it is
probably a sinkhole deposit derived from Hawthorn sediments. The unit
occurs in the south-central portion of Gilchrist County and northeast
Levy County in the study area.

Undifferentiated Sands and Sandy Clays

The Undifferentiated Sands and Sandy Clays (SSC) consist of variably-
colored, generally grayish-orange to dark yellowish-orange, fine to
coarse, clayey, quartz sands and sandy clays, which are poorly to
moderately-indurated. These sediments are often overlain by a light gray,
fine to coarse, unconsolidated to poorly-indurated quartz sand. In much
of the southern portion of the basin, this unconsolidated unit rests
directly on the limestone bedrock. The SSC unit (together with the Haw-
thorn and "Alachua" residuum) ranges in thickness from 0 to 140 feet,
with the greatest thickness associated with the upland areas in the
northern and northeastern portions of the basin and with the various
sand ridges (Figure 34). This unit increases in thickness toward White
Springs and Lake City to at least 188 feet, primarily due to the increased
thickness of the Hawthorn sediments. Much of the basin is covered with
less than 10 feet of sands and clayey sands, and limestone is at or near
the surface in extensive areas.
Fresh-water marls (3 to 4 feet thick) are reported to commonly occur in

REPORT OF INVESTIGATION NO. 96

oT30' eo00' ,2

30ooo' +

o 5 CMI
o S i0 2KM

EXPLANATION o
o Ft. to 20 Ft. o
21Ft.to40Ft.
S41Ft.to60R. o
A 61R.to80tR.
o 81 R. to 40 Ft.
140Ft.tol80R.
+ SSC present,but thickness of
unit indeterminable
----Limits of "Alachua" Fm.
- Limit of Hawthorne Fm.
(Limits south of Lake City from Williams,1971)
SYMBOL i(*lThickness of Hawthorn
S N =Data from Miller,1978
| 12=Unpubl. data from W.Yon,
Srangeof undif. sand Flo.Bur.Geology
Thickness range of undif. sand 8 clays

+ 0s- 0'

+29"150

Figure 34. Thickness of the sands and sandy clays, including the Haw-
thorn Formation and "Alachua Fm.", where present, in the
Lower Suwannee River Basin.

BUREAU OF GEOLOGY

the Suwannee and Santa Fe river valleys, and they are also deposited on
the bottoms of lakes and streams (Vernon, 1951; Puri et al., 1967).
Ponds and lakes generally contain beds of brown, fibrous peat, sandy
muck, and lenses of sapropel muds (Vernon, 1951).

Local Structure

Vernon (1951) mapped the linear features that appeared on aerial pho-
tographs of northern peninsular Florida and concluded that the lineations
were fracture traces. He noted two major fracture systems, trending in a
northwest-southeast direction and in a northeast-southwest direction.
The distribution and alignment of these traces with the Ocala Uplift led
Vernon to conclude that the fractures were produced by the same
stresses that formed the uplift. He also noted that stream paths and the
distribution of solution features were at least partially controlled by the
fracture trends. Vernon proposed the existence of two major fault zones
in Citrus and Levy counties on the basis of these lineations and on limited
well and outcrop control. They are the Long Pond Fault and the Bronson
Graben (Figure 35); Yon and Puri (1962) and Puri et al. (1967) extended
the Bronson Graben into Gilchrist County.
Vernon (1951) stated that it was "not surprising that in a thick lime-
stone section containing little close zonation and covered by considera-
ble Pleistocene and Recent alluvium and marine deposits that these small
faults have gone so long without being recognized." He tried to piece
together small bits of evidence to obtain a reasonable structural pattern
and he hoped that additional data collected in the future would provide
better control. Unfortunately, little new data are available that penetrate
the section in that area. Thus, the question of whether the Bronson
Graben and Long Pond Fault exist, as Vernon (1951) and Puri et al.
(1967) interpreted them from limited data, remains open for further
investigation. This investigator inspected the well and auger samples
used by the above-mentioned investigators to define the features and
found that most samples were now in poor condition or had missing
intervals. Thus, it was not possible for this investigator to support the
existence of the structural features or to offer alternative interpretations
about the linear traces.

HYDROGEOLOGY

Previous Investigations

A number of hydrogeological studies in the vicinity of the Lower
Suwannee River Basin have been published. Meyer (1962) conducted a
reconnaissance of the geology and groundwater resources of Columbia
County. Clark et al. (1964) reported on the water resources of Alachua,
Bradford, Clay, and Union counties. Briel (1976) described the hydro-
geologic setting of the Santa Fe River Basin. Puri et al. (1967) presented

REPORT OF INVESTIGATION NO. 96

so'oo' ( -

0 5 10MI
0 5 10 0 KM

EXPLANATION

FAULT

R9E RIOE RIlE PRIZE RISE

RI4E RISE RI6E

Figure 35. Location of the Bronson Graben and Long Pond Fault, pro-

posed by Vernon and Puri (after Vernon, 1951, and Purl et
al., 1967).

RI7E

+ 0S- 00'

T65S

T7S

T9S

T1OS

T12S

ION (1951)
n Graben"
T13S

+ 29s15

-IL ~

BUREAU OF GEOLOGY

a brief discussion on the groundwater of Dixie and Gilchrist counties.
Ceryak (1977) investigated the hydrogeology of the Alapaha River Basin.
The correlation of spring locations with lineaments and fracture traces
along the Suwannee River from Mayo to Branford, Florida, was investi-
gated by Beatty (1977). Various aspects of the karst hydrogeology of the
Upper Suwannee River Basin were presented in a Southeastern Geologi-
cal Society (1981) guidebook. The hydrology of the Upper Suwannee
River Basin was discussed by Ceryak et al. (1983) and that of the adja-
cent coastal basin will be addressed by Copeland and Burnson (in press).

Methods

Potentiometric contour maps and a potentiometric level fluctuation
map were constructed utilizing water level data, collected from a net-
work of Floridan aquifer wells sampled regularly by Suwannee River
Water Management District personnel and stored in SRWMD files. Rain-
fall data for selected areas were also extracted from SRWMD files. Water
level data for a select number of Floridan aquifer wells were acquired
from the USGS subdistrict office in Tallahassee, Florida.

Results and Discussion

GROUNDWATER FLOW AND FLUCTUATIONS

Burnson (1982) divided the hydrogeology of the Suwannee River
Water Management District into three classes (Figure 36). Class I is the
area of the unconfined, sole-source Floridan aquifer. Class II is a transi-
tional area in which a semi-confined Floridan is overlain by a semi-
artesian secondary system or a water-table aquifer. Class III is an area
characterized by a water-table aquifer, secondary artesian, and Floridan
primary artesian systems.
In the Lower Suwannee River Basin only the Class I and Class II sys-
tems are of areal importance (Figure 36). In the coastal swamps, the
Lower Suwannee and western Santa Fe river basins, the Floridan aquifer
is generally unconfined and under water-table conditions. The absence of
any significant overburden over either the Suwannee Limestone or the
Ocala Group limestones allows rainfall to directly infiltrate into the aqui-
fer. Thus, all of Class I region may function as a recharge area (Burnson,
1982).
The Class II area is characterized by a water-table aquifer, in some
areas a secondary artesian aquifer, and a semi-confined Floridan aquifer.
The surficial or water-table aquifer is composed of undifferentiated post-
Miocene deposits (primarily quartz sand) and Middle Miocene Hawthorn
Formation, member A (sands, clays, carbonates) (Figure 37). The water-
table aquifer is underlain by an aquitard made up of the massive clays of
member B (Ceryak, 1981) and the more clayey portions of member A.

10 0 10. 20 30 Miles

EXPLANATION

CLASS I
UNCONFINED FLORIDAN
AQUIFER

CLASS II
SEMICONFINED FLORIDAN
AQUIFER

CLASS III
CONFINED ARTESIAN AQUIFER
SYSTEMS

HAMILTON ::::::'

S *. . . *

SUWANNEE COLUMBIA:

Border of
SRWMD

Figure 36. Hydrogeological classification of the Lower Suwannee River Basin (outlined in black) and vicinity
(after Burnson, 1982).

D

BUREAU OF GEOLOGY

R 11 E R 13 EGEORGIA
S R...... ----- R 15 E17 E
S.... .... .:----.-...... .. ..... "

-:A I O C:.HAMILTON Co. ...
SASPER

CADISON CO.

0 .KM......... ........ .

EXPLANATION
Ex AREAL EXTENT OF I :. '- lljjp^ i^ J^H iIj:^ H;;;;;;,::,.ii> iY aiiiitj=
SURFICIAL AQUIFER .i| i
C SINKING STREAMS
SSINKHOLE LAKES
ScoDY SCARP 0

Figure 37. Extent of the surficial aquifer in the Upper Suwannee River
Basin and the northeast portion of the Lower Suwannee
River Basin (after Ceryak, 1981).

Members A and B of the Hawthorn Formation were described by Miller
(1978).
The surficial aquifer receives its recharge from precipitation which
migrates vertically to the water table indirectly through the overlying
sediments or more directly through the bottoms of ponds and lakes. The
water level fluctuates with changes in precipitation and evapotranspira-
tion. Water levels within this aquifer are generally at or near land surface
and often exhibit the same levels as those observed in swamps, lakes,
and ponds. The wells completed into this aquifer are mostly private
water wells less than 50-feet deep which supply adequate quantities for
domestic use.
Water from the surficial aquifer can recharge the underlying Floridan
aquifer by vertical flow through the underlying aquitard or more directly
through solution features and discontinuities in the aquitards. The surfi-

REPORT OF INVESTIGATION NO. 96

cial aquifer has limited vertical drainage throughout much of the Northern
Highlands due to thick Hawthorn confining layers underlying the aquifer.
However, at the Cody Scarp (Figure 37) where the aquitard is truncated,
the surficial aquifer discharges its water by means of gravity springs
(Ceryak, 1981). Water table aquifers associated with the Class II areas
within the LSRB are located in the western portions of Madison, Taylor,
and Lafayette counties; in the clayey sand and sand ridge areas of Gilch-
rist and Levy counties; and in the clayey sand and sand ridge areas of
Suwannee and Columbia counties. Copeland and Burnson (in press) have
described the water-table aquifer of the San Pedro Bay area of Taylor
County. This water table aquifer is up to 50-feet thick and composed of
loose, plastic sediments that are underlain by a thin, usually less than
five-feet thick, clay layer. Generally, the water table elevation is one to 5
feet higher than the potentiometric surface of the underlying Fioridan
aquifer. The geologic setting of the Class II area in Gilchrist and Levy
counties is an area of sand hills underlain by clayey sands that are consid-
ered part of the "Alachua Formation." In much of the Northern High-
lands, the water table aquifer is underlain by a secondary artesian aquifer
located within the Hawthorn Formation carbonates. The Cody Scarp
(Figure 37) is the boundary for the extent of the secondary artesian
aquifer since the upper confining beds have been eroded away in the
Coastal Lowlands (Ceryak, 1981). This aquifer generally lies outside the
borders of the LSRB.
The artesian-nonartesian boundary within the Floridan aquifer gener-
ally lies along the Cody Scarp, but the zone migrates in accordance with
aquifer recharge and discharge. If the thickness of the basal Hawthorn
clays and carbonates is less than 50 to 70 feet, the beds do not consti-
tute confining beds for the Floridan, since the beds have become
solution-riddled, leaky, and discontinuous (Ceryak, 1981). Thus, the
Floridan is semi-confined in this zone. South of the transition zone, the
Hawthorn sediments are entirely absent; and, as a result, the Floridan
aquifer is unconfined. Most of the LSRB contains a Floridan aquifer
which exhibits these characteristics.
The Floridan aquifer is composed chiefly of limestone and dolomite,
interbedded with minor amounts of clay and sand. The principal strati-
graphic units (Figure 7) comprising the aquifer include the Oldsmar and
Lake City Limestones (corresponding roughly to the Undifferentiated
Carbonate Lithofacies), the Avon Park Limestone (corresponding roughly
to the Dolomite Lithofacies), the Ocala Group limestones, and the
Suwannee Limestone (Miller, 1982a). In the LSRB, virtually all the fresh
groundwater is pumped from the shallow Floridan aquifer (predominantly
the Suwannee Limestone and the Ocala Group limestones). A small num-
ber of wells may penetrate into the Dolomite Lithofacies.
The top of the Floridan aquifer in the LSRB is the top of the Suwannee
Limestone in the northern third of the basin and the top of the Ocala
Group limestone in the southern two-thirds of the basin. The top of the
aquifer is at or near the land surface throughout most of the LSRB.

68 BUREAU OF GEOLOGY

The base of the Floridan aquifer is not well documented in the LSRB.
Klein (1975) inferred the base of the potable water zone of the Floridan
aquifer with the base ranging from 1200 feet below land surface in the
northeast LSRB to less than 250 feet below land surface at the mouth of
the Suwannee River. Klein defined potable water as having a chloride
content of less than 250 mg/I and a dissolved solids content of less than
500 mg/l. The base of the aquifer could only be inferred due to the lack of
deep well data.
Miller (1982a; 1982b; 1982c; 1982d) published contour maps show-
ing various characteristics of the Floridan aquifer. He defined the base of
the Floridan aquifer on the basis of lithologic criteria such as presence of
interstitial gypsum and anhydrite in well samples taken in peninsular
Florida. Based on these criteria and a limited number of wells, the base of
the Floridan System was estimated to be 1300 feet below land surface in
the northeast LSRB, 1100 feet below land surface in Gilchrist County,
and 1700 below land surface at the mouth of the Suwannee River. The
thickness of the Floridan aquifer system in the LSRB ranges from 1300
feet to 1600 feet with the thinnest area centrally located where Gilchrist,
Dixie and Lafayette counties meet. The base of the freshwater zone in
the system was defined using water sample data in which water contain-
ing less than 10,000 mg/I dissolved solids was classified as freshwater.
The base of the freshwater zone became more divergent from the
lithologically-defined base as the Gulf Coast was approached. Near the
coast, the base of the freshwater zone was shown to be hundreds of feet
closer to land surface than the base defined by lithologic criteria. Spar-
city of data precluded a more accurate determination of the base of the
system. Since adequate supplies of freshwater are available from shal-
low depths of the Floridan aquifer in the LSRB, it may be many years
before additional data becomes available to more precisely define the
boundaries of the Floridan system.
The potentiometric surface of the Floridan aquifer in the Lower Suwan-
nee River Basin (constructed from data collected May 1980, November
1980, and April 1981, respectively) is shown in Figures 38-40. These
maps are constructed by plotting and contouring the water-level eleva-
tions measured in tightly cased wells tapping the upper Floridan aquifer.
The resulting surface, actually a map of the hydraulic heads in the aqui-
fer, is called a potentiometric surface (Bouwer, 1978). In most of the
LSRB, the aquifer is unconfined; thus, the potentiometric surface and the
water table surface are the same. In the northeast part of the study area,
where the Floridan aquifer is semi-confined or confined, the potentiomet-
ric surface represents water levels under artesian conditions, i.e., the
water levels in tightly-cased wells completed into the aquifer rise above
the top of the aquifer.
The configuration of the contour lines is controlled by the permeability
of the sediments and by the water flow characteristics in the aquifer. The
direction of groundwater flow is perpendicular to the contour lines and
down the hydraulic gradient from areas of high hydraulic head to areas of

REPORT OF INVESTIGATION NO. 96

30*00 -

4

9 5 I MI
0 5 10 20 KM

EXPLANATION

3 OBSERVATION WELL
-50, POTENTIOMETRIC
CONTOUR, INTERVAL 10 Ft.,
DATUM IS NGVD OF 1929.
DATA COLLECTED MAY 1980

Figure 38. Potentiometric surface of the Floridan aquifer in the Lower
Suwannee River Basin, May 1980.

69

+ 30o 00
T6S

T7S

T8S

T9S

TIOS

T11S
+29 30

TI2S

T13S

+ 29.15'

~~~_IL--L~L-L I~~__ -- _- II t
~~I --^^

BUREAU OF GEOLOGY

+

3oO +

3 5 C MZ

3 5 1C 20 KM

EXPLANATION

26* OBSERVATION WELL
.-1o-.POTENTIOMETRIC
CONTOUR,INTERVAL 10 Ft,
DATUM IS NGVD OF 1929.
DATA COLLECTED NOV. 1980.

Figure 39. Potentiometric surface of the Floridan aquifer in the Lower
Suwannee River Basin, November 1980.

T5S

+30o0oo

T7S

TBS

T9S

TIOS

TIIS
29* 30

T12S

T13S

+ 29-'IS

REPORT OF INVESTIGATION NO. 96

30.00' +

0 5 10 MI
6 5 10 20KM

OBSERVATION WELL
--,70- POTENTIOMETRIC
CONTOUR, INTERVAL 10 Ft,
DATUM IS NGVD OF 1929.
DATA COLLECTED APRIL 1981

Figure 40. Potentiometric surface of the Floridan aquifer in the Lower
Suwannee River Basin, April 1981.

+- o o00'

s

S
+230

IS

+ 29-15'

--I~L Il--------s---~t-I~L

BUREAU OF GEOLOGY

Figure 41. Areas of natural recharge to the Floridan aquifer relative
to the potentiometric surface of the Floridan aquifer, May
1980 (modified from Rosenau and Milner, 1981; and Ste-
wart, 1980).

low hydraulic head. Generally, this flow direction is from areas of
recharge to the aquifer to areas of discharge from the aquifer (Figure 41).
The groundwater in the Floridan aquifer in the study area generally
flows in two directions, toward the Suwannee River corridor and toward
the Gulf of Mexico. Groundwater flows from the aquifer to the river
where the river lies at a lower elevation than that of the potentiometric
surface of the aquifer. However, in periods of high precipitation, the flow

REPORT OF INVESTIGATION NO. 96

is reversed when the surface elevation of the river rises above the poten-
tiometric surface of the aquifer.
The potentiometric contours in the LSRB exhibit a pattern in which
they parallel the rivers and bend upstream (Figures 38 41). This pattern
indicates leakage of groundwater into the rivers (Puri et al., 1967). In
these areas, the Suwannee River and the Santa Fe rivers are sustained by
groundwater flow from the aquifer. The contours parallel the Suwannee
River as far upstream as Hamilton County and the Santa Fe River as far
upstream as southeastern Columbia County. In the northernmost part of
the LSRB, the Suwannee River flows over the less permeable deposits
that overlie the Floridan aquifer carbonates; the characteristic bending of
the contours is absent, indicating little groundwater contribution to the
river flow.
The contour patterns in the LSRB generally did not change significantly
from May 1980 through April 1981 (Figures 38-40). Water levels did
decrease from May 1980, a wet season, to November 1980, a dry sea-
son, particularly in the northern half of the basin. From November 1980
to April 1981, the water levels rose slightly at some wells, although
nowhere near to their May 1980 levels. Most wells, however, continued
to decrease from their November 1980 level. The Suwannee River basin
average rainfall from August 1980 through July 1981, was only 74
percent of normal, or about 14 inches below normal (SRWMD, 1981).
This decline in rainfall accounted for the decrease in groundwater levels
from November 1980 to April 1981 exhibited in Figures 38-40.
A network of Floridan aquifer water-level monitoring wells has been
established by the Suwannee River Water Management District. Figure
42 shows the wells in the network where water-level measurements
were taken at least 13-14 times at regular intervals from November
1976 to April 1981. Although the measurement frequency changed from
four measurements annually to two measurements annually during this
time span, all annual measurements were taken in a synoptic system at
all wells. Figure 42 also shows the percentage of water level measure-
ments at each well in which the water level measurement varied 5 feet or
more from the measurement made during the previous measurement
event.
The wells in which most of the large fluctuations occurred are located
in the northern portion of the basin along the Suwannee River. These
wells are associated with the higher recharge areas of the basin or with
the river corridor. River corridors show the greatest groundwater fluctua-
tions; they probably have the highest transmissivities. Rivers tend to
occupy zones of structural weakness in which secondary porosity of the
adjacent aquifer rock is increased by the greater dissolution of limestone
through contact with acidic ground and surface water in these areas.
Vast corridors of solution channels are known to exist along the Suwan-
nee River (Exley, 1977; 1978). Copeland and Burnson (in press) reported
maximum quarterly water-table fluctuations to be greatest near river
corridors in the SRWMD area. During the periods of backflow when the

BUREAU OF GEOLOGY

R9E RIOE RIIE RI2E R13E RI4E RISE RI6E RI7E

5 !CMI
S C ZCMt
3 C 2C KM

EXPLANATION
eN PERCENT OF WATER LEVEL
MEASUREMENTS IN WHICH
M Mz 2 5 feet
WHERE

AND
Time 1 precedes Time 2
o USGS Water Level Measurement Wells

Figure 42. Map showing 1) the well location and the associated per-
centage of water level measurements in which the water
level measurement at the well varied five feet or more from
the previous measurement at the well, and 2) the locations
of USGS Water Level Measurement Wells.

TIS

T2S

0
T3S

T4S

T5S

+- so 00o

T6S

T7S

TBS

T9S

TIOS

TIIS

T12S

TISS

+ 29- 15'

I

REPORT OF INVESTIGATION NO. 96

river recharges the aquifer, wells near the river can be influenced. Some
of the areas exhibiting high frequencies of the large fluctuations are
located in the high recharge areas of the basin where precipitation
directly recharges the unconfined water-table aquifer.
The wells that exhibited few large fluctuations are associated with
areas of low recharge or high discharge (Figure 41, Figure 42). In areas
where recharge is very low-to-moderate, semi-confining or confining lay-
ers retard and regulate the flow that reaches the aquifer, providing the
water indirectly to the aquifer by leakage from overlying surficial aqui-
fers. Topographically low areas of low-to-moderate, or zero recharge, are
generally areas where the aquifer is discharging; the precipitation tends
to run off since the water level of the water-table aquifer is at or near land
surface.
The amounts of monthly precipitation that fell at selected sites in the
LSRB from January 1979 to March 1981 are shown in Figures 43 and
44. Water levels at USGS monitoring wells completed in the Floridan
aquifer plotted as monthly averages, for the same time period as above
and as near to the precipitation measuring sites as possible, are also
shown in Figures 43 and 44. The USGS well locations are shown in
Figure 42. The patterns of precipitation at all six locations are similar.
Wells at some of the locations exhibit water-level fluctuations, some of
which can be associated with the corresponding precipitation fluctua-
tions. Generally, though, there is a weak correlation or no correlation
between precipitation and well levels at most of the selected wells.
Those with the best association between precipitation patterns and
water-level patterns are at White Springs (167' deep, cased to 75' below
land surface), and at Suwannee Springs (58' deep, cased to 49' bis),
both near the Suwannee River and in a high recharge area. Other wells
that exhibit significant water level fluctuations, although no direct corre-
lation between precipitation and water-level patterns are evident, are at
Mayo (146' deep, cased to 112' bis) and Trenton (101' deep, cased to
55' bls) in areas of high recharge. Two wells show minor fluctuations
and virtually no direct relationship between precipitation and water lev-
els. The Lake City well (836' deep, cased to 680' bis) is a deep well
located in an area where a relatively thick confining layer overlies the
aquifer. The Cedar Keys well (442' deep, cased to 442' bls), also a
relatively deep well, is located in an area of discharge near the Gulf
Coast.
The majority of the LSRB can be classified as an area of high recharge
(Figure 41). Most of the high recharge areas are regions where the car-
bonate aquifer rocks are exposed at land surface or are covered with a
veneer of quartz sands. The northeast portion of the LSRB has very low
recharge because the overlying sands, sandy clays, and clays thicken
and limit or retard recharge to the Floridan aquifer. The areas of the LSRB
classified as having very low-to-moderate recharge are areas that: (1)
have a layer of sandy clays overlying the aquifer that retard the down-
ward flow to some extent (e.g., San Pedro Bay, Bell Ridge) and (2) have

75

BUREAU OF GEOLOGY

1979 1980 1981

70

.*o.
6 0 ". .

,..*^-^*****<*****-^"

A
.---- J %
^ -^^ --'
r

I \
I \
I r

%*
-d" 40--

*......WHITE SPRINGS
---SUWANNEE SPRINGS
-CEDAR KEYS

- ~ ~ :03 S- -- -~L~ So zoO1

0- i I I I I I l l I I I l l I I I I I I I I I I
F M A M J J A S O N O J F M A M J J A S 0 N D J F M
1979 1980 1981

Figure 43. Rainfall from January 1979 to March 1981 at White

Springs, Suwannee Springs, and Cedar Keys in the Lower
Suwannee River Basin (upper) and water well level eleva-
tions from January 1979 to March 1981 at the same sites
(lower). Well data are from USGS (1980, 1981, 1982).

Z g

-I

U. 6'

I-
0-
LU

20-
0-
Il
_1

10'

REPORT OF INVESTIGATION NO. 96

w
8

..J
_1
_-
LL

4

-
UJ
LiJ
- 40-
Z
I-
< 30-
LJ
_J
UJ

201

1979

1980

p'2-- I.

0 1 1 1 1 _ I I 1 .1 1
J F M A M J J A S O N D J F M A M J J A S O N D J F M
1979 1980 1981

Figure 44. Rainfall from January 1979 to March 1981 at Lake City,
Mayo, and Trenton in the Lower Suwannee River Basin
(upper) and water well level elevations from January 1979 to
March 1981 at the same sites (lower). Well data are from
USGS (1980; 1981; 1982).

" ****.....e ,

----LAKE CITY
MAYO
....... TRENTON

BUREAU OF GEOLOGY

a potentiometric surface (water-table) that is near or at land surface
(e.g., Levy County coastal swamps, Mallory Swamp in Lafayette
County, Dixie County coastal swamps). Areas of zero recharge are
restricted to a coastal strip in Taylor County outside of the LSRB.

SPRINGS

The LSRB study area contains at least 33 named springs (Figure 45).
All springs but one (Levy Blue) are located along the Suwannee River
corridor where the cavernous carbonates of the Floridan aquifer lie near
or at the land's surface. According to Rosenau et al. (1977), "A spring is
the water discharged as natural leakage or overflow from an aquifer
through a natural opening in the ground."
Springs can be categorized according to the type of aquifer from which
they derive their flow, artesian or water-table. The majority of springs in
the LSRB are of the water-table type because the Floridan aquifer is
unconfined.
The spring flow results from the differential between the hydrostatic
head at the spring vent and that in the recharge area. Where the Suwan-
nee River channel has cut into the aquifer rocks and the river level is
lower than that of the water-table, springs flow into the river. The major-
ity of the springs emerge from solution cavities connected to solution
conduits that can extend for miles into the rocks of the aquifer system.
Lafayette Blue Spring (Green Cave System) and Peacock Springs System
have been mapped in detail by cave scuba divers of the National Spe-
leological Society; these two spring systems each consist of miles of
solution channels (Exley, 1977; 1978). A generalized cross-section of a
typical spring in the karstic Suwannee River Basin is shown in Figure 46.
The groundwater discharges from the channels of the aquifer into the
head pool where the water flows down the spring run into the Suwannee
River channel. Sinkholes, as shown, also can locally recharge the spring.
Springs are also classified by Meinzer's magnitude of discharge sys-
tem (Rosenau et al., 1977). Under this system, springs are classified by
magnitude, from one to eight, on the basis of their volume of flow or
discharge. A first-magnitude spring has average flow greater than 100
cubic feet per second; a second-magnitude spring has average flow
between 10 and 100 cubic feet per second; a third-magnitude spring
discharges 1 to 10 cubic feet per second (Rosenau et al., 1977).
Five first-magnitude springs are located in the LSRB study area: Ala-
paha Rise, Falmouth, Troy, Fannin and Manatee. Twenty-two second-
magnitude springs are located in the LSRB: White, Suwannee, Ellaville,
Suwanacoochee, Charles, Allen Mill Pond, Lafayette Blue, Telford, Pea-
cock, Running, Owens, Mearson, Little River, Ruth, Branford, Fletcher,
Turtle, Rock Bluff, Sun, Hart, Oldtown Copper, and Levy Blue. Six third-
magnitude springs were included in the study: Lime, Anderson, Royal,
Guaranto, Otter, and Bell. All first-and-second-magnitude springs in the
LSRB were sampled in this study. All of the springs sampled discharge

REPORT OF INVESTIGATION NO. 96

B8OO:
*MADISON BLUE
RIOE RIIE PRIZE RI3E

RI4E R15E R16E R7TE

Figure 45. Map showing 1) Suwannee River Water Management Dis-

trict monitor wells in the Lower Suwannee River Basin and
vicinity, and 2) springs in the LSRB and vicinity.

8330'

R9E

TAYLOR CC

3000' +

0 5 0IMI

0 5 10 20KM

EXPLANATION

SPRING
NETWORK WELL

+ 29 30

,,,, __ ____

- --llL II

+30 -00'

oOLIMESTONEE

4--
SLELIMESTONE ON
0 . . ..

W' r~* -- ..

o S A o 15 s o 25 ,

Basin (after Briel, 1976).

REPORT OF INVESTIGATION NO. 96

into the Suwannee River, except for Suwanacoochee Spring, which dis-
charges into the Withlacoochee River, just north of its confluence with
the Suwannee River and Levy Blue Spring which discharges into the
Waccasassa River (Taylor and Snell, 1978). Anderson Spring is reported
by scuba divers to be in the bed of the Suwannee River (Rosenau et al.,
1977).
It can be seen that the Suwannee River valley is the site of a potentio-
metric low (Figures 38-41). Such lows can be excellent indicators of
the location of numerous or large springs (Rosenau et al., 1977). In the
northern portion of the basin, the low occurs because the river has
eroded through the confining beds that overlie the aquifer, thus exposing
the aquifer. In the central and southern areas, the unconfined water-table
aquifer is breached.
Beatty (1977) investigated the relationship between linear features
and the locations of springs in a segment of the Suwannee River from
Mayo to Branford. She reported a strong correlation between the loca-
tion of the springs in that segment of the river and the occurrence of
linear features intersecting the river corridor. It is thought that these
lineations are the surface manifestations of underlying joint and fracture
patterns (Vernon, 1951) that are conducive to the formation of solution
channels and conduits that are known to exhibit high transmissivities
and create the outlets for springs (Lattman and Parizek, 1964; White,
1969).
Along the Suwannee River from Anderson Spring to Thomas Spring
(SW1/4 SWW/4 SW1/4 sec. 9, T4S, R11E), no springs are evident. An
examination of the geology and potentiometric surface of this river seg-
ment yields no explanation for this anomaly. It is possible that springs
exist but are located in the bed of the river (such as Anderson Spring) and
have not yet been reported. Seeps into the base of the river are known to
occur in other areas of the river (David Fisk, Suwannee River Water
Management District, personal communication).

GROUNDWATER CHEMISTRY

Previous Investigations

Although the USGS and the Suwannee River Water Management Dis-
trict personnel have collected water quality data in the Suwannee River
Basin for many years, only recently have investigators attempted to
interpret the geochemical patterns in a regional framework utilizing
advanced statistical methods. One tool used by these investigators is the
R-mode factor analysis as outlined by Dalton and Upchurch (1978).
Lawrence and Upchurch (1978) published an interpretation of hydro-
chemical faces in the Lake City area derived by factor analysis. Ceryak
(1977) used a similar procedure to delineate three aquifers in the Alapaha
River Basin on the basis of hydrochemical patterns. Ceryak et al. (1983)
and Copeland and Burnson (in press) have used the technique to interpret

BUREAU OF GEOLOGY

groundwater quality patterns in the Upper Suwannee River Basin and the
adjacent coastal basin, respectively.

Methods

SAMPLE COLLECTION AND ANALYSIS

Water quality data for all wells located within the Lower Suwannee
River Basin that had been sampled by the SRWMD staff between fall
1975 to April 1981 were used in the construction of regional geochemi-
cal pattern maps and in the statistical analyses.
Samples for uranium analysis were collected by this investigator at 32
springs and 62 water wells in the basin from summer 1980 through April
1981. Six wells were sampled on two separate occasions. In conjunction
with most uranium samples, an additional water sample was collected
for water quality analysis.
Springs were sampled as close to the seepage boil as possible. Well
pumps were run for at least five minutes in order to flush the system,
particularly when the sample was taken after passage through the pres-
sure tank. Several casing volumes were discharged to insure a represent-
ative sample.
Each sample consisted of a completely full 500 ml bottle and a 250 ml
or smaller polyethylene bottle. The 500 ml sample remained untreated,
while the smaller portion was acidified to a pH of approximately 2.0. This
was done to preserve metals in solution for laboratory analysis. A portion
of the untreated sample was filtered through a 0.45 micron membrane
filter and retained in a third bottle. Temperature, specific conductivity,
and pH were measured in the field when the sample was collected. All
samples were kept on ice in a cooler until they were returned to the
laboratory.
Chloride, fluoride, and silica concentrations were measured from the
filtered portion of the sample. Total alkalinity and dissolved orthophos-
phate were determined from the untreated and unfiltered portion of the
sample. Total calcium, magnesium, sodium, and potassium were mea-
sured on the unfiltered, acidified portion of the sample. Methods of anal-
ysis for alkalinity, calcium, magnesium, potassium, and sodium were
reported in United States Environmental Protection Agency (1974);
methods used for chloride, fluoride, sulfate, ammonia, nitrate, nitrite,
and orthophosphate were reported in American Public Health Associa-
tion (1977); the method of analysis for silica was reported in American
Society of Testing and Materials (1977).

DATA PROCESSING

To reduce the data to an easily interpreted form, R-mode factor analy-
sis (Davis, 1973) was undertaken using the routine FACTOR of the Sta-
tistical Package for the Social Sciences-SPSS (Nie et al., 1975). The

REPORT OF INVESTIGATION NO. 96

method of factoring chosen was the PA2 (principal factoring with itera-
tions). The final factor solution employed was the orthogonal, Varimax-
rotated, factor solution with Kaiser normalization. This analysis was
done using the Florida State University CYBER 74 computer system.
After calculating factor score coefficients as explained by Harmon
(1967), factor scores for each sample were computed as outlined by
Klovan (1975). The R-mode analysis allows description of covariance
between variables. Those variables that are interdependent represent
process-response relationships; those that are independent represent
independent processes. The factor scores which are calculated for each
sample indicate the importance of each factor at that sample site. Inter-
pretation of factor scores is simple in that each cluster of related varia-
bles (process-response relationship) is characterized by one new varia-
ble, the factor. With standardized and normalized data, scores less than
- 1 or greater than + 1 represent those samples that exhibit the least or
most intense responses, respectively, to the process represented by the
factor (Lawrence and Upchurch, 1978; Dalton and Upchurch, 1978).
Factors with eigenvalues less than 1.0 were not accepted in the analy-
sis. The percentage of the correlation (based on communalities) of each
parameter was examined for each run of the program. If the factor analy-
sis results accounted for less than a specified percentage, the program
was rerun without the data of that parameter. This meant that the pat-
terns of distribution of these particular parameters were weak and that
they varied either randomly or not at all. Since these parameters have
little or no pattern, they contribute little hydrogeologic information; thus,
they can be deleted from the data matrix. The remaining variables can be
used as input for another factor-analysis run.
Various investigators in this field disagree on the necessity of normal-
ization of the raw data. In order to be conservative, normalization of the
data was attempted. The data were normalized as much as possible
through transformation of the data. Various logarithmic and power trans-
formations were applied. The most acceptable results were obtained
through use of the square root transformation. Skewness and kurtosis
values were brought significantly closer to those values expected for
normally distributed data. The transformed data values were used as
input into the factor analysis. The untransformed data were also used as
input in order to compare the resulting factors.
The factor analysis program used generally calculates and inputs Pear-
son's correlation coefficient into the matrix. An option in which the Ken-
dall's Tau coefficients are calculated and input was also implemented.
Those who argue for normalization of the raw data point out that the
validity of the Pearson's coefficient is defined with the assumption of
normality. The Tau coefficient, however, is a non-parametric statistic
that does not assume normality as a condition of its validity. The factor-
analysis routines were run using both coefficients as input to the matrix
to compare the factors obtained.

83

BUREAU OF GEOLOGY

Results and Discussion

GEOCHEMICAL PATTERNS AND DISTRIBUTION

Suwannee River Water Management District well drillers' completion
logs indicated that most water wells within the study area were com-
pleted into either the Suwannee Limestone or the Ocala Group lime-
stones. The logs indicated that most wells were less than 100 feet deep;
however, some wells up to 200 feet deep are located in the northern
portion of the basin where the sands and sandy clays overlying the
limestones are thickest. Some shallow wells (less than 50 feet deep) in
the areas where the sands and sandy clays are thickest, appear to be
completed into perched water tables that overlie the Floridan aquifer. A
few deep wells, 200 to 500 feet deep, are located in the basin and are
usually associated with municipal water supply systems. Chemical
parameter distribution maps were constructed for fifteen parameters:
pH, specific conductivity, alkalinity, chloride, fluoride, sulfate, silica,
orthophosphate, nitrate, ammonia, calcium, magnesium, magnesium-to-
calcium ratio, sodium, and potassium. Since most wells were completed
into a stratum limited in vertical extent, the chemical parameter distribu-
tion maps were constructed to show areal (geographic) distribution of
the values. Inspection of these maps later revealed that approximately
39 of the 720 wells were probably completed into perched water tables
rather than into the Floridan aquifer. These wells were easily delineated
on the basis of pH, specific conductance, and calcium values.
The pH values ranged from 4.3 to 9.0. Generally, the lowest pH values
were grouped in the northeast portion of the study area (Figure 47). Most
samples had pH values between 7.0 and 8.0; however, values between
6.5 and 7.0 were common in the southern portion of the basin. Extensive
swamps and marshes in the southern portion may account for the lower
pH values due to infiltration of organic acids into the limestone aquifer.
The lowest pH values, less than 6.5, were found to be related to wells
completed into the shallow perched aquifer in the northern portions of
the basin. The vast majority of pH values correspond to those expected
to occur in a carbonate aquifer.
Two patterns of distribution are most noticeable in the specific con-
ductivity values: (1) the lowest values, less than approximately 50
micromhos/cm are grouped in the northeast part of the basin; and (2)
most values lie between 200 and 500 micromhos/cm (Figure 48). Con-
ductivity values range from 25-2617 micromhos/cm. The lowest con-
ductivity values, less than 100 micromhos/cm, were measured in the
surficial perched water table wells; however, many of the surficial wells
have values greater than 100 micromhos/cm, up to 898 micromhos/cm.
The extremely high conductivity values probably are due to saltwater
intrusion and upwelling of deep connate water or transport of saltwater
aerosols into the aquifer. The specific conductivity is due to the concen-
tration of ionic species or salts in solution. Dissolved salts in ground-

REPORT OF INVESTIGATION NO. 96

30ooo +

o 5 10 MI
S 5 10 20 KM

EXPLANATION

LESS THAN 6.50
6.50-7.00
7.01-7.50
7.51- 8.00
GREATER THAN 8.00

Figure 47. Distribution of pH values measured in wells and springs in
the Lower Suwannee River Basin and Lake City area.

BUREAU OF GEOLOGY

30-00'

Hooo

0 5 10MI
O 10 0 KM

EXPLANATION

SPECIFIC CONDUCTIVITY
LESS THAN 100 )LMHOS/CM
o 100-200
201-400
n 401-500
GREATER THAN 500JLMHOS/CM

Figure 48. Distribution of specific
wells and springs in the
Lake City area.

conductivity values measured in
Lower Suwannee River Basin and

30 oo00

T6S

T7S

T8S

T9S

TIOS

TIIS
+29 30'

T12S

T13S

+ 29TISS

- I I __~~

II _

	Title Page
	Letter of transmittal
	Table of Contents
	List of Illustrations
	List of Tables
	Abstract
	Acknowledgement
	Introduction
	Description of study area
	Physiography and geology
	Hydrogeology
	Groundwater chemistry
	Uranium hydrogeochemistry
	Groundwater-surface water...
	Summary and conclusions
	References
	Appendix I. Description of cuttings...
	Appendix II. Well data from cuttings...
	Appendix III. Well location...
	Copyright

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