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Geology and ground-water resources of Leon County, Florida ( FGS: Bulletin 47 )
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Table of Contents
    Title Page
        Page i
    Front Matter
        Page ii
        Page iii
        Page iv
    Table of Contents
        Page v
        Page vi
        Page vii
        Page viii
        Page ix
        Page x
    Acknowledgement
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        Page xii
    Main
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Full Text

STATE OF FLORIDA
STATE BOARD OF CONSERVATION
DIVISION OF GEOLOGY



FLORIDA GEOLOGICAL SURVEY
Robert O. Vernon, Director


BULLETIN NO. 47


GEOLOGY AND GROUND-WATER RESOURCES
OF
LEON COUNTY, FLORIDA

By
Charles W. Hendry, Jr. and Charles R. Sproul















Published for
THE FLORIDA GEOLOGICAL SURVEY



Tallahassee
1966







FLORIDA STATE BOARD

OF

CONSERVATION

iS- 7. s7
^ 3 6>



HAYDON BURNS
Governor


TOM ADAMS
Secretary of State




BROWARD WILLIAMS
Treasurer




FLOYD T. CHRISTIAN
Superintendent of Public Instruction


EARL FAIRCLOTH
Attorney General




FRED O. DICKINSON, JR.
Comptroller



DOYLE CONNER
Commissioner of Agriculture


W. RANDOLPH HODGES
Director






LETTER OF TRANSMITTAL


Lorida jeological Survey

Callakassee
May 19, 1966

honorable Haydon Burns, Chairman
'lorida State Board of Conservation
'allahassee, Florida

,ear Governor Burns:

The Division of Geology, of the Florida Board of Conservation
I publishing as Bulletin 47, "Geology and Ground-Water Resources
f Leon Courty, Florida," prepared by Charles W. Hendry, Jr. and
harles R. Sproul, geologists with the Division.
Leon County has an excellent, large, potable supply of water
available in the Floridan Aquifer, which is largely undeveloped.
iarge additional supplies are available for expansion of municipal
r industrial supplies. The total use of water averages about 12
million gallons per day, but yields up to 5,000 gpm are possible
nd a yield of several hundred gallons per day could be sustained.
Of the natural contaminants, only iron occurs in amounts that
rould be objectionable. The water is moderately hard and re-
rires only chlorination for municipal use.
Only limited resources of shell, sand, clay, and sandy clay
re available for development.

Respectfully yours,
Robert 0. Vernon, Director
and State Geologist





















































Completed manuscript received
May 19, 1966
Published for the Florida Geological Survey
By E. O. Painter Printing Co.
DeLand, Florida

iv










CONTENTS


Acknowledgements --.--- ----- -_ __-. ............ ._

Introduction ..

Setting --- -- --..- ... ...-- ___..............

Purpose -... ....... .......

Location and extent ....--__-.......

Maps .- --...................

Population and development --..................

Transportation -...... ----...._......._..............

Highways ... .......--- .......

Railroads

Airways _---.. .-.. ............_ ..................

Bus lines -- -....

Climate -.__.-----.-......____-...............

Locality and well numbering system ---.--

Previous investigations ----................._

Geology -- ----.------.......-....

Introduction- ... ... .. .... ..-

Physiography --...-. ........_.- ..............

Northern Highlands --- -_--................___

Tallahassee Hills .---__-----.............

Gulf Coastal Lowlands ------.. -----

Apalachicola coastal lowlands ----.--

Okefenokee dunes -.. .....

Woodville Karst Plain -......- .........

Lake Munson Hills --. ....

Wakulla Sand Hills ..........

River valley lowlands -__--.....-..........

Ochlockonee River Valley Lowlands

St. Marks River Valley Lowlands .


Major streams ..------

Ochlockonee River _

St. Marks River ..--.

Lakes and lake basins

Lake lamonia -..-----

Lake Jackson --...--

Lake Lafayette -----

Lake Miccosukee .----

Lake Talquin .--..--

Lake Bradford ---.-

Lake Munson -.....--

Lake Hall -.

Other lakes -...------

Stratigraphy .....------..

Introduction ....---------

Paleozoic Era --..--.

Ordovician System _


-.....--.. xi

.............--- 1








2
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......... 2
--.....--.. 5

--........- 6
............. 6



7

7
--.--.-.....- 7

------------- 7


...----.- ........ -..... 7


S9

8

9

.. 11

.---- 11

-... 22

.... 23

-.- 24

... 26

.... 27

.- 29


-..---.-- .... .... .... 29


Beds of lower Ordovician Age .


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--------------- - ----------- --..~ ~~ 47






Mesozoic Era -..----------- ------------ -- 47
Triassic System _- ----------------------- -------47
Beds of Upper Triassic Age .---__ ...----------------- ----- 47
Newark (?) Group ------- ------- 47
Cretaceous System. ------------------ 49
Comanche Series ------- ----- -----.----. 49
Beds of Lower Cretaceous Age .------------------------ 49
Gulf Series -------------- 49
Atkinson Formation 4---------------------------- ----- 49
Austin Chalk ...------------- 50
Beds of Taylor Age ------ ------------------------ 50
Cenozoic Era _--. .. .. ...----------------- --51
Tertiary System ---- -.--------- ----------------51
Paleocene Series -----------..-------------------- 51
Beds of Midway Age ------------- ------ 51
Eocene Series .------------------ 51
Beds of Wilcox Age .-------- -------------51
Claiborne Group _------------------------------ 52
Lake City Limestone ------------- -- 52
Tallahassee Limestone --- ----- ---------------------- 52
Avon Park Limestone .---------------------------- 52
Jackson Age .-. ..------------ 53
Ocala Group --------------- ------------------ 53
Crystal River Formation ------------------------ 53
Historical _------------------------ 53
Definition and distribution .------------------- -- 53
General lithology ... .. ....----------- ---------- 55
Stratigraphic relations ------------------- 55
Thickness and structure .----------------- 55
Aquifer .. ----------------- 55
Oligocene Series ------------ ----------- 58
Suwannee Limestone ------------------ ------------ 58
Historical .. ..--------------------------- 58
Definition and distribution -------58
General lithology ------------ 58
Stratigraphic relations ------------- 59
Thickness and structure --------- 59
Aquifer -------------------60
Miocene Series ---------------- 60
Tampa Stage --------- ----------------------------- 60
St. Marks Formation ------------------ 60
Historical --- ----- ------------------ 60
Definition and distribution ------- 62
General lithology ------ 62
Stratigraphic relations --------- 62
Thickness and structure 63
Aquifer .__-.- ...------. --------------- ------- 63
Outcrops _--.. ..---- -.. .. .. 63
Alum Bluff Stage ----------.-- -------------------- 65
Hawthorn Formation --------------- 65
Historical -...--.-------------------------- 65
Definition and distribution 66





General lithology --- ------66
Stratigraphic relations --------_ ---- 67
Thickness and structure -- -- 67
Aquifer ------ ---68
Outcrops _------ --- ----__ 68
Choctawhatchee Stage ------- ----- -- 75
Jackson Bluff Formation ------__ ---- 75
Historical ------- -____-_~___ _ 75
Definition and distribution 75
General lithology -----_-_- 75
Stratigraphic relations __---------- 75
Thickness and structure --- ---- 76
Aquifer --- -----_-____ _______ ______ 77
Outcrops __ __ 77
Miccosukee Formation --------- -- 78
Historical 78
Definition and distribution ---_ --- 82
General lithology -------------_ ____82
Stratigraphic relations --____ __ 84
Thickness and structure ----------. ---84
Aquifer ----- ------__ __ ____-____- 87
Outcrops ----- ------~_-- -____ 87
Quaternary System _----------_ ______ 92
Pleistocene Series -------______ ______ 92
Introduction --_________-___-_ 92
Okefenokee Formation --------- 92
Wicomico Formation -- ------------- 92
Recent Series ._ ------ _. _- - - -_ ________ 92
Structure __.__---------- -.----------__ ____.... --......._ 94
Peninsular Arch ------- -------_ 95
Apalachicola Embayment --------___ ___ ____ __95
Gulf Trough ------------------ 96
Linear trends --------- ......... ..-----. ............ ... ... 97
Economic geology --_ --------.-------- .-- ....-__-__-... .... ...... 99
Clays .. . .. . .. .. -------------------- 99
Sands and gravels -------------------------....-___ .____... __ 101
Marl m soe- ------------------. ---------. --_~__-._... ..__ 101
Limestone -------------------------.. .. -------104
Phosphate 104
Petroleum - - --... . .. __..._.._........ ---........._ 104
Ground water ..-------------------__ ___ ..--___.__.- -- ...... 105
Principles of occurrence ----.. -----------------------------.--___ .-_--...._ 105
Aquifers and aquicludes in Leon County -------------------_.- .___.. __. 106
W ater-table aquifers -----------------__ -__ ___- ___-__._. __._. ..... .. 106
Floridan Aquifer .------------_ ---. -.------._____.__... .__._. 106
Hydrologic features of carbonate aquifer _____-------- __.... 108
Relationship of hydrology to stratigraphy in Leon County __.....__ 109
Ground-water conditions in Leon County -------111
Piezometric surface ---------------------------......- 111
Recharge ---------------------------------------. ... ...... 112
Discharge _____--------_ -------------------------.... 115
Water-level fluctuations --------------- ---------------------115





Fluctuations caused by rainfall ---- ------ 116
Fluctuations caused by pumping --------- 119
Other water-level fluctuations --------_- 120
Utilization of ground water ----------- 121
Municipal supplies _------------ 121
Private supplies --------------- 121
Irrigation _...-------------------------------- 122
Industry ------------------ 122
Air conditioning --------------- 122
Drainage wells -------------- 123
Availability of ground water ------_-- 123
Specific capacity ---.--.....--------------------- 124
Aquifer tests ......---------------------------- 128
Water quality .....-.------------------------------..-.. 130
Constituents ----- -- ---------- 131
Iron --. .------------------------------- 131
Iron removal ---______ ..-- -------...... ---- ..--- 135
Calcium and magnesium ... ------------------.--- 135
Sodium and potassium -------------135
Bicarbonate .----------------------------- 136
Sulfate ----------------------------------- 136
Chloride -...--------------.--- --- --.------------ -------- 136
Fluoride .---------__---------------------- 136
Silica __---------_-- --------------------- 137
Nitrate -------------------- ---------- -- 137
Properties ...--------------------------------- -- 137
Hardness ....-------------------------------- 137
Hardness reduction -..--------------.-- 138
Total dissolved solids _.----------------------.-----13 138
Specific conductance _____-_...------------------------ 139
Hydrogen ion concentration ------------------------------- 139
Hydrogen sulfide ..--------------------------- ---- 140
Color -.... -----.. ........- -- --------------------- 140
Temperature _._. ----------------- -------------... 141
Highly mineralized water ........-------------------- .--- 141
Pollution --._-- ..----------------------------------- 141
Pollution by drainage wells and sinkholes ------ 142
Pollution by heat ....------- ------------------- 142
Summary and conclusions _------ ---- -..1.-. .-. 146
Appendix ----------------------------------- 149
Bibliography ......----------------- --------- -----. 167
Index -------....----------------------- 175

ILLUSTRATIONS
Figure Page
1 Location of the Big Bend area and Leon County, Florida. -- 3
2 Index to topographic quadrangles -------- 4
3 Graph showing comparative population growth of Leon
County and the State of Florida. -___----_ -- 5
4 Graph showing the average monthly rainfall and tempera-
ture in Tallahassee, Florida. ----------- 8





5 Locality and well numbering system used in this report. ------- 10
6 Diagrammatic stratigraphic sections. ______------ 12
7 Location of wells from which geologic and hydrologic data
were obtained. __----.----~ ---------------_ 13
8 Physiographic subdivisions in Leon County ------------ 25
9 A portion of the Woodville topographic quadrangle showing
the Natural Bridge area. _------------------------ 32
10 Lake lamonia "sink." -.. ... _____.__ .______.-- --_-_-- 39
11 Photograph of the Lake Jackson Basin during low water stage. ---- 40
12 Lake Miccosukee Basin during the low water stage in 1957.
Dam cuts off drainage into large sink hole on northwest
shore of lake. _--__------ --------______--_---__ 43
13 Lake Bradford basin during the low water stage, May 10,
1955 (note mud cracks). -.... ___ _____------------- 45
14 Gamma-ray log of well WLn-2N-3E-11-ca, Leon County
showing the relative difference in the radioactivity of the
Upper Eocene and Oligocene sediments. ------ 56
15 Geologic cross-sections. __________--------- 57
16 Structure map of Oligocene sediments. --_. ------- 61
17 Structure map of Lower Miocene sediments. _---- 64
18 Limestone of the St. Marks Formation overlain by plastics of
middle Miocene age (locality LLn-1N-1W-30-bb). ---- 66
19 Oyster bed in middle Miocene sediments at locality LLn-1S-
1W-3-da. ___--- _____ _----- -------- 69
20 Jackson Bluff Formation (very macrofossiliferous) uncon-
formably overlain by younger sediments -- ___-- 76
21 Laminae and thin beds of clay within the Miccosukee Forma-
tion (locality LLn-3N-1E-17-aa) _-_..-_- ---------------------- 83
22 Localities LLn-3N-3E-20-bd and LLn-1N-1E-21-ab depicting
the occurrence of sandstone float in the Miccosukee Formation. ----- 85
23 Disorientation of thin beds in the Miccosukee Formation by
faulting, locality LLn-3N-3E-2-cc. __ _----------- 86
24 "Micro" hardpan in sediments of Pleistocene age at locality
LLn-2S-1E-24-ad. ......--- -------------------- 94
25 Linear trends as depicted on a mosaic of the county. --- 98
26 Piezometric surface of Floridan Aquifer following a period
of near average rainfall. ___ _____ -------------- -- 113
27 Piezometric surface of Floridan Aquifer following a period of
extremely high rainfall. ._~_. _-------- --_----- 114
28 Range of water level fluctuation. -_ --- 117
29 Hydrographs of selected wells showing long range water
levels, and graphs of rainfall. ------------ 118
30 Hydrographs of well WLn-1N-1E-30-ac-1 depicting daily
fluctuations. __--------------- 119
31 Diagrammatic sketch showing cone of depression in piezo-
metric surface. -_.. ..---.--- 124
32 Diagrammatic presentation of specific capacities in selected
wells. __--- ---------------- - 128
33 Theoretical drawdown in a well producing from the Floridan
Aquifer. ____. ____- --------- 130
34 Chemical composition of artesian water in selected wells. ---...--- 134

ix





35 Relationships of Total Dissolved Solids and Hardness to
specific conductance. ---- --___ _... - ------- 140
36 Location of wells used in pollution test at the Florida State
University. --- ------ --__-- 144
37 Current-meter, temperature, and tracer surveys in Florida
State University pollution test. 145

Table
1 Population of towns in Leon County ---------- 2
2 Geologic and hydrologic data from wells. ._...---- -- 14
3 Stratigraphic units with related water-bearing characteristics --. 21
4 Correlation of Pleistocene terraces. --------- 28
5 Stratigraphic nomenclature chart. ------- 48
6 Analysis of clay samples. -. _-- --_ --- -------- 102
7 Specific capacity for selected groups of wells. ----- -- 126
8 Water quality for selected wells. ___- ---_ -- 132

Plate
1 Geologic map. --_--- -- ------ --- In pocket





ACKNOWLEDGEMENTS
This study was begun in the Spring of 1959 as a companion
study to one being conducted by J. W. Yon, Jr. in adjoining
Jefferson County, Florida. It was conducted "intermittently"
through 1965.
The writers were assisted in the initial stages of the field work
by J. A. Lavender and Jack Woodward, geologists, formerly with
the Florida Geological Survey.
Charles Sever, U. S. Geological Survey, Dr. Ray Gremillion,
Florida State University, and E. W. Bishop, Division of Water
Resources and Conservation, Florida Board of Conservation,
accompanied the authors in the field on several occasions and
contributed invaluable assistance in discussions on the geology
of the area.
The writers are especially appreciative of the assistance given
by J. W. Yon, Jr. during frequent field trips and for helpful
discussions of the geologic problems inherent to the area.
To the many members of the Water Resources Division, U. S.
Geological Survey, Tallahassee, Florida, who contributed much in
the early stages of the field work on the ground-water investiga-
tion, and for many hours of discussion and constructive criticism
the writers are very grateful.
The writers express their thanks to the members of the staff
of the Florida Geological Survey for long hours of faithful endeavor
in preparing maps and illustrations, typing, proofing and editing
the manuscript, and to the geologists for discussions and sugges-
tions that led to a more complete understanding of the problems
involved.
The citizens of the county were very cooperative during this
study through their interest and assistance. Though many well
drillers have contributed samples from wells drilled in the area,
the following well drillers were especially cooperative during this
study.
Rowe Brothers Well Drillers-Tallahassee, Florida
Barnes Pump and Well Drilling Company-Tallahassee, Florida
Carr Drilling Company-Thomasville, Georgia
Terra Rosa Hardware-Tallahassee, Florida
Throughout the investigation the City of Tallahassee Engineer's
office provided data on city wells, and the writers are appreciative
of this cooperation.




To Dr. R. 0. Vernon, Director, Division of Geology, Florida
Board of Conservation, who encouraged the writers during the
course of the investigation, and who contributed so much to the
understanding of the geology of the area through innumerable
discussions and frequent assistance in the field, the writers are
very grateful.





GEOLOGY AND GROUND-WATER RESOURCES
OF
LEON COUNTY, FLORIDA
By
Charles W. Hendry, Jr. and Charles R. Sproul
INTRODUCTION
SETTING

Sediments on the eastern flank of the Gulf of Mexico basin
have been divided into the North Florida Province and the South
Florida Province by Pressler (1947, p. 185). The North Florida
Province is composed predominantly of plastic rocks while the South
Florida Province is composed primarily of limestones, marls,
and evaporites. The line separating these provinces extends from
Levy to Nassau counties, Florida. Puri and Vernon (1959, 1964,
p. 1) accepted this same boundary line between the provinces, but
they have applied the names North Gulf Coast Sedimentary
Province and Florida Peninsular Sedimentary Province.
For a broad regional study of the entire sedimentary section,
Pressler's line of demarcation is reasonably valid; however, this
boundary is not applicable when smaller portions of the strati-
graphic column are singularly considered. The reason is that the
boundary actually shifts geographically through geologic time
(Chen, 1965). For example, the clastic-non-clastic boundary
during Cretaceous time is coincident with that of Pressler. From
Cretaceous through Paleogene time the separation is to the west
of the Apalachicola River, and for Neogene time the division can
be placed well down the Peninsula at about the latitude of Lake
Okeechobee. The Big Bend area of Florida, of which Leon County
is a part, therefore, falls within both provinces.

PURPOSE

Population and industrial trends in the Big Bend area of Florida
not only indicate a need for additional information of the mineral
deposits, but also for additional information on the occurrence
and availability of ground-water resources.
The purpose of the investigation was to make a detailed study
of the geology, and to examine within certain limits, the ground-
water resources of Leon County. The study was started in mid-





2 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

1959 and has been conducted intermittently since that time. Data
on the geology were collected through examination of the surface
exposures and through examination of the cuttings and cores
from oil tests, water-supply wells, and core holes. The core holes
were drilled by the Florida Geological Survey in specific areas
where sufficient subsurface data was not available. Data on the
ground-water resources were obtained through the inventory of
selected water-supply wells, including the measurement of water
levels and the chemical analyses of water samples.

LOCATION AND EXTENT

Leon County is situated in the center of the Big Bend area,
lying about midway between the Apalachicola and Suwannee rivers,
as shown in figure 1.
The county is slightly irregular in shape, roughly resembling
the side profile of a high-top shoe. North to south it measures
approximately 28 miles in the eastern half and 10 miles in the
western portion. East to west it is approximately 38 miles in the
southern half and 18 miles in the north portion. The total area
is approximately 685 square miles.
Leon County is bounded to the north by the State of Georgia;
to the east by Jefferson County; to the south by Wakulla County;
to the extreme west by Liberty County; and to the northwest by
Gadsden County. The Ochlockonee River and Lake Talquin
separate Leon County from Liberty and Gadsden counties.

MAPS

Leon County is completely covered with U. S. Geological Survey
topographic quadrangles, and the index to the published maps
is shown as figure 2. With the exception of the Lake Talquin and
Tallahassee sheets, these maps are 71/-minute quadrangles at a
scale of 1:24,000. The Lake Talquin and Tallahassee sheets are
15-minute quadrangles at a scale of 1:62,500. All the quadrangles
have a 10-foot contour interval with the exception of the Cody
and Woodville sheets, which have a 5-foot contour interval.
The U. S. Department of Agriculture county photograph index
sheets served as a crude mosaic, from which stream flood plains,
scarps, ancient shore lines and surface lineation were taken. An
up-to-date State Road Department county transportation map was
used as an aid to routes and location descriptions. The base map
used in this report was compiled from the topographic quadrangles.











A:


GEORGIA
RIW. + RIE + R2E + R3E


S BIG BEND AREA


4 2 0 4 8 12 MILES
APPROX. SCALE -COUNTY


S .. I Woodville
WAKULLA \ '
COUNTY
R5W R4W + R3W 4- R2W + RIW + RIE + R2E + R3E


Figure 1. Location of the Big Bend area and Leon County, Florida.


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Figure 2. Index to topographic quadrangles.
Figure 2. Index to topographic quadrangles.





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 5

POPULATION AND DEVELOPMENT

Leon County is the most populous county in the Big Bend area.
In 1960, the U. S. Census reported 74,225 residents, and the 1964
figure is estimated to be 84,000 (Kiplinger) to 87,000 (City of
Tallahassee). For the year 2000, the county population projection
is 225,000 people (City of Tallahassee). The county was created
in September 1824 while Florida was still a territory, and at that
time had a population of about 1,000. During the 100 years
following the creation of the county, the population only increased
by about 20,000. However, since the 1930's there has been a rapid
rise in population, and the county trend has kept pace with that
of the state as a whole, as shown in figure 3. In 1914, the population
density was 27 persons per square mile; in 1964, the population
density was approximately 111 persons per square mile. In 1964,
Leon County ranked 14th as the most populous and most rapidly
growing county in Florida (Florida Development Commission).
Tallahassee, the county seat, has two large state universities
(Florida State University and Florida Agricultural and Mechanical
University), and is the site of Florida's state capital. Also, it is

59---- .. 5




90 -- --90

0 --- 870 I
0o ---8 80------
I I0 r10
GO-
50
3040 -- ^ -4 >- 40 1

2 30- + -- --+ tFLORIDA -30
0 2 F--- 1 . ...---20 0--- -0


Figure 3. Graph showing comparative population growth of Leon County
and the State of Florida.





6 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

the largest urbanized area in the Big Bend. Tallahassee has
approximately 67 percent of the county's population, and the
Tallahassee urbanized area brings this to approximately 85 percent.
Other population centers in the county are the small rural
communities of Miccosukee, Woodville and Chaires, shown in
table 1.
Over 70 light manufacturers or processors, two universities,
the state capital, general agriculture and timber are the county's
major sources of income.
The rapid increase in the population, coupled with the
accompanying increase in industry, creates the need for more
information concerning the mineral and water resources. The
satisfaction of this need is based on an adequate up-to-date
geological and hydrological survey of the area. This survey
provides data on the occurrence and availability of mineral
resources and the occurrence and development of the county's
water resources.

TRANSPORTATION

HIGHWAYS

The City of Tallahassee is located very near the geographic
center of Leon County. Three major U. S. highways (27, 90, 319)
intersect at Tallahassee, as do six important paved county and
state roads.
U. S. Highway 90 crosses the county west to east, and U. S.
Highway 27 crosses Leon County northwest to southeast, placing
Tallahassee and the county on important transcontinental routes.
These roads are heavily traveled by visitors to Florida, as well
as by commercial traffic. U. S. Highway 319 traverses north to
south and serves as an important route for many who travel from
inland states to the Florida coast in the Big Bend area. This high-
way also joins with U. S. Highway 98, an east to west coastal
route just south of Leon County.

TABLE 1. Population of towns in Leon County.

1950 1960 1964

Tallahassee 27,237 48,174 58,022
South City 4,611 1,148
Miccosukee 175 120
Woodville 350 400
Chaires 70 85





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 7

State Highway 20 connects Tallahassee with the cities and
counties to the southwest of Leon County, and carries much traffic
to and from the Panama City-Pensacola area.
The other paved state roads, along with numerous paved and
unpaved county roads, provide an excellent network of intercon-
necting routes throughout the county.
Interstate Highway 10 is to be a transcontinental superhighway
across the southern portion of the U. S. This highway, partially
completed, subparallels U. S. Highway 90, and is scheduled to pass
through Leon County, just north of the City of Tallahassee.

RAILROADS

Leon County is served by only one railroad, the Seaboard Air
Line Railroad Company, that crosses the county from east to west.
There are several passenger and freight schedules each day
through Tallahassee, giving good service to Jacksonville on the
east and Pensacola, Mobile, New Orleans and others on the west.

AIRWAYS

Daily scheduled flights into the Tallahassee airport are provided
by Eastern Airlines and National Airlines. Eastern Airlines
provides service north and south, and National Airlines provides
service east and west. Direct flights to desired destinations in
the Southeast are available through unscheduled local charter air
transportation service.

BUS LINES

Tallahassee is served by the Greyhound Bus Corporation and
Trailways Bus Company, with frequent schedules on the U. S.
highways and the trans-state highways. These bus companies also
provide excellent freight service to and from Tallahassee.

CLIMATE

Climate has been an important factor in the evolvement of
the geology of the Leon County area. Its geographical position is
reflected in the humid subtropical climate, and the water derived
from the high annual rainfall is the principal factor in the erosion
of surface sediments and in the removal of the carbonate substrata





8 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

by dissolving action. The average annual temperature in
Tallahassee is 67, varying from an average low of 53.6' in January
to an average high of 81 in July (U. S. Department of Commerce).
The average precipitation is 56.66 inches with the heaviest rainfall
in the summer months, as shown in figure 4.

LOCALITY AND WELL NUMBERING SYSTEM

The locality and well numbering system used in this report is
based on the location of the locality or well, and uses the
rectangular system of section, township and range for identifica-
tion. The number consists of five parts. These are: 1) a prefix
of three letters designating L for locality or W for well and county
abbreviation, 2) the township, 3) the range, 4) the section and
5) the quarter/quarter location within the section.
The basic rectangle is the township which is 6 miles square.
It is consecutively measured by tiers both north and south of the
Florida base line, and an east-west line that passes through
Tallahassee as Township ? North or South. This basic rectangle
is also consecutively measured both east and west of the prinicpal
meridian and a north-south line that passes through Tallahassee
as Range ? East or West. In recording the township and range
numbers, the T is left off the township numbers, and the R is left
off the range numbers. Each township is divided equally into
36 square miles called sections, and are numbered 1 through 36
as shown on figure 5.

90 90
80 8 8 80
70 7 7 70
n 60 6Fl-60.
TEMPERATURE ,
50= 5 550t
L u I z LIU
40 14 47 40
30 3 3 30'
20 2 2 20
10 1 1 10

JAN. FEB. MAR. APR. MAY JUNE JULY AUG. SEPT. OCT. NOV DEC.

in Tallahassee, Florida.





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 9

The sections are divided into quarters with the quarters labeled
"a" through "d" as shown on figure 5. In turn, each of these one-
quarter sections is divided into quarters with these quarter/quarter
squares labeled "a" through "d" in the same manner. The "a"
through "d" designation of quarters may be carried to any extent
deemed useful.
The location of the well WLn-2N-2E-21-db as shown on figure
5 would be in the center of the southeast quarter of the northeast
quarter of section 21, township 2 north, range 2 east, Leon County.
When there is more than one well or locality in a square 40-
acre tract (quarter/quarter section) they are identified by either
an additional quarter designation or by a sixth arbitrary accession
number at the end. The abbreviations used for counties in this
report are: Ga for Gadsden, Jf for Jefferson, Ln for Leon, Lb for
Liberty, Th for Thomas, and Wa for Wakulla.

PREVIOUS INVESTIGATIONS

There have been numerous reports which pertain to botany,
topography, general geology, paleontology, stratigraphy, and
ground water of the Florida Big Bend area. Many of these are
excellent reports; however, none of the more inclusive ones deals
principally with Leon County. Good bibliographies of the earliest
of the publications can be found in the annual reports of the
Florida Geological Survey. The writers have referenced only those
reports that are more comprehensive and applicable to a better
interpretation of the geology and ground-water resources of Leon
County.
Leon County mineral-production tabulations have been included
in reports on the mineral resources of Florida in most of the
annual reports of the Florida Geological Survey and in the annual
summaries in the U. S. Department of the Interior, Bureau of
Mines Minerals Yearbooks. Additional reports on the numerous
resources are by Vaughn (1902), Vernon (1943), and Calver (1949,
1957).
Wilder, et al., (1906) published an early soils report on Leon
County. Harper (1910, 1914) and Davis (1946) have reported on
the peats and vegetation of Florida with specific references to
Leon County. General geological reports which include Leon
County are by Sellards (1909, 1910, 1912, 1914, 1914a 1917, 1922),
Matson and Clapp (1909), Matson and Sanford (1913), Cooke and
Mossom (1929), Cooke (1939, 1945), Applin and Applin (1944,







10 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN


z

I-


6 5 4 3

7 8 9 10

18 17 615

19 20( 07 22

30 29 8 27

31 32 33 34


2

11

14

23

26

35


1

12

13

24

25

36


Figure 5. Locality and well numbering system used in this report.





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 11

1947), MacNeil (1944, 1949), Applin (1951), Puri and Vernon
(1959, 1964), and Doering (1960).
Reports on the vertebrate paleontology of the area have been
made by Sellards (1916), Simpson (1929, 1932), Colbert (1932),
and Olsen (1959, 1964). Ray (1957) has prepared an excellent
tabulation on Florida Vertebrates entitled "A List, Bibliography,
and Index of the Fossil Vertebrates of Florida." Reports on the
micropaleontology of subsurface formations of the area have been
by Cushman (1919, 1921), Cole (1944, 1945), Applin and Applin
(1944), Puri (1954), Puri and Vernon (1959), and Cole and Applin
(1961).
Discussion on the early water resources of this part of Florida
have been presented by Sellards and Gunter (1912a), and a list of
publications touching on some aspects of the water resources is
available in Florida Geological Survey Special Publication No. 4.

GEOLOGY

INTRODUCTION

Early attention was given the Leon County area by staff
geologists of the Federal and Florida Geological Surveys. These
early reports were principally of the surface geology and
vegetation, but as more subsurface information became available
from wells, information on the stratigraphy, structure, and
paleontology was published.
During the last few years numerous water-supply wells have
been drilled in Leon County, and the data gathered from over 160
wells and 29 core tests have permitted a more detailed interpreta-
tion of the subsurface sediments from Upper Eocene through the
Recent, as shown in figure 6. Several tests drilled in the search
for oil and gas in this section of the state have yielded more limited
data on sediments as old as Early Ordovician Age. The surficial
sediments range in age from Early Miocene through Recent. Table
2 lists selected wells located within the area of investigation from
which geologic and hydrologic data were obtained. The table
includes surface elevation, depths below land surface to tops of
formation, and sources of data. Figure 7 is a map of Leon County
which shows the locations of these wells.
Throughout the county most water-supply wells extend through
the plastic overburden and terminate in the artesian limestone
bedrock. Only a few dug water-table wells are used in the county.






Series

Recent and
Pleistocene





Miocene


Choctawhatchee

Alum Bluff

Tampa




Jackson


North South

Formation Formation


Stage






Choctawhatchee

Alum Bluff


Tampa




Jackson







Stage


Absent


Miccosukee
Formation
Hawthorn
Formation
St. Marks
Formation
Suwannee
Limestone
Crystal River
Formation




West

Formation

Wicomico
Formation
Okefenokee
Formation
Jackson Bluff
Formation
Hawthorn
Formation
St. Marks
Formation
Suwannee
Limestone
Crystal River
Formation


Pamlico (dunes)

Wicomico Fm.

Absent (eroded)

Absent (eroded)


St. Marks
Formation
Suwannee
Limestone
Crystal River Fm.


B'


East

Formation

Wicomico
Formation
Absent (eroded)


Absent (eroded)

Thin to absent


St. Marks
Formation
Suwannee
Limestone
Crystal River Fm.


Oligocene

Eocene


Series


Recent and
Pleistocene


Miocene




Oligocene

Eocene


Figure 6. A-A' is a north to south diagrammatic stratigraphic section in the
eastern half of the county and B-B' is a west to east section in the southern
half of the county depicting occurrence of the stratigraphic units from Upper
Eocene to Recent age.






R5W + R4W


R3W + R2w +


RIW + R1 E + R2 E R3E
SG E 0 R G I A


z



LEGEND 43 2 1
7 18 1 10 11 12
SWell location 11 12
z ---- Line of cross section 15 14 1
1 9 2 21 122 23 24
30 29 28 27 28 25
31 32 33 34 35 36
4- SECTIONIZED TOWNSHIP


z ....



+"


RSW R4W + R 3W


- R2W R1W


RI E


R2E R3E


Figure 7. Location of wells from which geologic and hydrologic data were obtained.


0
0
0

z




0
0




z


H


0

Ci2
cl









0
0


















z

0

z
H
Cl
H






tR
H
0
L'
Q
0


O
d





TABLE 2. Uses and Remarks: O-observation; S-samples; el.-electric log;
gr.-gamma ray log; WS-water supply well; D-drainage well; WA-water
analysis; WL-periodic water level measurement or water level recorder;
T-test; AS-air conditioning supply; AR-air conditioning return.


Well Number


WTh 4N-1W-34 cc

WGa 3N-1W-19 b

WTh 3N-1E- 5 c

WLn 3N-1E-15 b
-15 ed
-19 de
-20 d
-32 cc

WLn 3N-2E-14 d
-16 a
-16 c
-17 c
-27 b
-28 ba
-30 ad

WLn 3N-3E-32 bbb

WJf 3N-3E-36 da

WGa 2N-2W-22 aal

WGa 2N-2W-22 aa2

WLn 2N-1W- 2 be
-12 ba
-22 a


Ea


I
0


Casing


$2


'C
a


4fS
4

5)


Depth to top of Geologic Formation


SE


S5)
'~0


S.O
20


i

-5u
w c


>1 L
a)


z
01
W'S
o
4)~


h-- d- I d h-- 1--- 1--- I S -- L--- WZZ..VL _________"


Use


Remarks


S

WA; WL

S

WL; dug
WA; WL
S; el
S
S; el

S; el; gr.
WA
WA; WL
WA; WL

S; el; gr.
WL

S; el; gr.

S

WA; WL

WL

S; el; gr.
S
WA


well


nr I c
1^ mi1






WLn 2N-1W-27 ac

WLn 2N-1E- 9 bd
-21 a
-21 b
-32 cc
-35 ca

WLn 2N-2E- 3 cb
8
-13 ab
-15 aa
-15 d
-20 bb
-30 cc

WLn 2N-3E- 4 ac
8 aa
8 bb
-11 ca
-21 db
-21 adb
-34 ad
-35 ac

WLn 1N-3W-33 dd

WLn 1N-2W-23 ca
-23 da
-25 da
-32 be
-35 ba
-36 cc
-36 dd

WLn 1N-1W- 1 cd
2 cdd
2 ddd
4 da
4 d
5 bb
-9d
9 ad
-11 abl
-11 ab2
-12 ddd
-13 b
-14 ad
-14 cad


6 192


0

0


0


40

62%


35
0

50
53
45
54
70
22
0

45
62
65
0


0
50




25
61
35


0
0
0

70

60
55
40
25
70
120
0
35


105

146


70


80
14212
55
98
90
70
80

98
154
105


- _
90



40
70
124
83
35
80

70
65
90
50
130
80
150
150
55
60
140
139
75
55


ws

T
Ws
Ws
ws
D

Ws
T
Ws
0
Ws
Ws
Ws

Ws
T
Ws
T
Ws
Ws
T
Ws

Ws

Ws
Ws
Ws
T
Ws
Ws
Ws

Ws
Ws
Ws
Ws
Ws
Ws
Ws
Ws
Ws
Ws
Ws
Ws
Ws
Ws


S

S; el; gr
WL
WA; WL
S; WA
el; gr

S
S; el; gr
S
WL; el; gr
S; WA
S; el; gr
S; el; gr

S; el; gr
S; el; gr
S; WA; el; gr
S; WA; el; gr
WA; WL
WL
S
S; WA

WA; WL

WL
S
S; WA; el; gr
S
S; WA
S; el
S

S; el
S; el
S; WA; el
S; WA
S
S WL
S
S
S; el; gr
S; WA; el; gr
S; city No. 16
el; gr
S
S


440


___ _____ I_____ __ ~i__









TABLE 2. (Continued)


Well Number


WLn 1N-1W-14 ccd
-15 a
-20 dd
-21 ba
-21 ad
-22 a
-22 db
-22 cc
-24 bbb
-25 cbe
-25 dbc
-26 ad
-27 aa
-27 ddc
-29 bbb
-29 bd
-29 dd
-29 bdd
-30 dda
-30 aac
-31 ddd
-32 dad

WLn 1N-1W-34 dba
-35 ba
-35 b
-35 abl
-35 ab2
-35 ab3
-35 ab4


147
247

165
61
118
237
60
210
130
162
137
52
202
80
88
85
87
72
80
105
84

170

101
94
116
117
78


.0
a
a


0


Casing


0?


Depth to top of Geologic Formation


wr


0
P 4 .O 02 r.O 4~0
a5 3F v5 c 5 o- )'
F l r ! ra j | a
pi o3 u t L6 v^ ^
S t, -o go "o *o
Q~~~h Kh; VIF*-& W ~


0


--.--.. 60
--..-.. 80

-... 0
0

..... 90
------. 0
0
80


r
a a
50
V.5

M


I


as
- a


z


1i
d,
'3 c


Use


Remarks


S; el
S; WA
S
S
S
WS
S; WA
S
S
S; WA; el city No. 10
S; WA; city No. 11
S
S
S
S
S; WA
S
S; WA
S
S
S
S

S
S
S; el; gr
S
S
S; el; gr
S; el; gr


' '





-35 bab
-35 db4
-35 dbl
-35 db2
-35 db3

WLn 1N-1W-36 cca
-36 bb
-36 ac
-36 bd
-36 cdl
-36 cd2
-36 dcd
-36 ddl
-36 dd2
-36 bdd

WLn 1N-1W-36 cddl
-36 cdd2
-36 dddl
-36 ddd2

WLn 1N-1E- 4 aac
5 bb
6 cc
8 de
-16 ac
-16 d
-19 ac
-20 dc
-22 da
-23 da
-23 ac
-27 aa
-30 db
-30 ac
-30 acl
-30 cc
-33 aa
-34 da

WLn 1N-1E-34 be

WLn 1N-2E-15 ca
-15 ac
-29 ab
-34 dc

WLb 1S-5W-24 ad


WS5 A l;ct o


60 130

60 113
-.---... 11-
-------- ------
115
110 125
100 165

105 215
185 235
120 235
89 190
110 204
65 158
80 180

100 195
40 180
50 160
55 160

110 260
141 201
87 158
135 275
90 170

120 235
55 90
150 200
80 130
75 125
100 160
115 240
135 235

120 220
90 130
100 210

85 210

185

90 220
.. .. -


WS
WS
AS
AR
AS

AR
WS
AR
WS
AS
AS
AR
AS
WS
AR

AS
AS
WS
WS

WS
WS
WS
WS
WS
WS
WS
WS
WS
WS
WS
WS
WS
WS
T,
WS
WS
WS

WS

WS
WS
WS
WS


00 240 34 221 0 el;gr


S; WA; el; city No. 9
S
S
S
S

S
S; WA; city No. 13
S
S
S
S
S; el; gr
S
S; WA; city No. 5-A
S

S
S
S; city No. 4
S

S; el; gr
S
el; gr
S
S; el
WA; WL
S; WA; el; city No. 12
S
S; el; gr
S
S
S
S; city No. 15
S; city No. 8
WL
S; el; city No. 6
S
S; WA

S; WA

S
WA; WL
S; WA
WA


O el; gr


90


240


54 221







TABLE 2. (Continued)


Casing Depth to top of Geologic Formation

W ----------------- 4 -- i

t I g i dI i

wa v A z 1 8 I i
Well 0N 0' 4 03 S
Well Number 8 Pk0 4o A C Use Remarks
ra E PP M ri2o, r, O r4 I
~" aP h~rr mF V6998i


WLn 1S-4W-11 db
-11 dd
-12 c
-15 ba
-20 c
-21 aa
-35 aa

WLn 1S-3W- 1 deb
3 bd
3 cc
6 ad
-13 a
-14 bb
-15 bb
-16 bb
-24 ca

WLn 1S-3W-25 bd
-34 ce

WLn 1S-2W- 2 aa
7 cc
-14 db
-19 cc
-22 ad
-23 aa
-23 cdd
-25 a
-28 cb
-29 da
-34 dd


220
127
193

100
132




23













232



112


6998
3907

3212

6599


3538

6999





AS-11



7525
AS-5
7526
AS-9
AS-8
6199

AS-6
AS-10
6019


S; el; gr
S; WA
WA; WL; el; gr
S; WA
WA
S; el; gr
WA; WL; el; gr


S

S
WL




S


WL
S
S
S
S
S
S; WL; el; gr
WA
S
S
S; WL


--- - -



230 --------
------ - -
------ ----


inn mu I Inn






WLn 1S-1W- 1 aa
1 aad
4 da
4 bb
4 cb
4 db
da
5 dd
8 de

WLn 1S-1W- 9 caa
-10 ca
-13 de
14 bb
-16 a
-16 bal
-16 ba2
-26 cb
-31 aa
-35 ba

WLn 1S-1E- 2 db
3 dba
3 da
3 dcb
4 dcb
4 ac
4 bad
4 bd
4 abd
4 bed
5 abb
6 aa

WLn 1S-1E-11 da
-18 cce
-19 c
-27 cd
-29 a

WLn 1S-2E- 3 cd
-15 b
-25 bbd
-29 cb

WLn 2S-4W-15 db

WLn 2S-3W- 4 bd
-14 db


76
190
88
60
89
89
41
72
67

56
85
82
52
70
40
40
29
56
25

73
213
213
205
213
193
220
212
216
219
212
155

215
54
51
25
40

53

40
45

109

112


141 ..
156 0
73 0
255 0
150 0
110 0
0
.--- 0

68 0
140 0
77 0
102 0

60 0
12 0
140 0
100 0


74 ---.
202
218

190
184
196

261
211
180
205


60
180
100
70
107
140
100

139

115
85
130
60



70





263
265
320

110
285
245
330
180
180

260
40

44
30

60

37
75


ws
AS
WS
AS
WS
WS
WS
D
WS

WS
WS
WS
WS
WS
0
0
ws
Ws
WS

WS
WS
WS
WS
WS
WS
WS
WS
WS
WS
AR
WS

T
WS
WS
T
WS

WS
WS
T
T

WS

WS
WS


--^- --;.-.~------------ -L~ ----------,------ I


I---- -


s
S; el; gr
S
S
S
S
S; WA
S
S; city No. 16

S
S; WA
S
S; city No.
WA; WL
WL
WL

S; el; gr
WL

S; WL
S; WA
S; WA
WA; el; gr
S
S
S; el
S; el; gr
S
S
S
S; WA; city No. 7

S
S; WA
S; WL
S
S

S; WL
WA
S
S

WA; WL

WA; WL
WA













TABLE 2. (Continued)


Casing Depth to top of Geologic Formation

>

w a, 0 :>
6 da 85 211 2 .. 53 66 98 7524 T S






-28 aa 23 70 4 42 10 35 3985 WS S
WLn 2-2E-15 bb 41 6520 .. 33 936 T S; el; oil test
Well Number & 0 C Use Remarks


WLn 2S-2W- 4 bd 95 47 2 ... 0 _-_. .-_. ..._ 46 --- --- T
6 da 85 211 2 0 -- 3 - 53 66 98 7524 T S
-18 aa 88 -90 4 432 0 49 62 ---- 1 7523 T S
WWa2S-1W-22 bd 21 43 4 .16- 0 . 5 10 -- 189 WS WA; WL

WLn 2S-1E- 8 dd 35 183 6 32 0 _- -_.--. ---_- 15 110 --- 6059 WS S; WA; WL
-11 cb 46 3755 ---- ----- 0 -- --.. ----- ...-._- <165 5 _-_- 32 T S; oil test
-28 aa 23 70 4 42 0 -- 10 35 3985 WS S
WLn 2S-2E-15 bb 41 6520 0 -.- - -- ..... 33 936 T S; el; oil test
-29 ba 18 90 4 43 0 --- 15 -- 4208 WS S
-29 da 21 175 4 163 0 5_-_ - _-_- 6 10 1892 WS S; WA; WL

WWa 2S-2-E-36 bdb 29 38 2 ....... 0 -. .... _. 20 36 .-... T S
WWa 3S-1E-14 aa 18 ....-... .-- ----.. ....---. 0 -.-- -. -- ----. ...-. 440 T S; el; oil test





j-S-naiu o. ou-raigrapnIL un IiLs WILI AeltauLL vv eL-er-Dtearing itaraciacueriables.


Geologic age


Recent and
Pleistocene



Pliocene (?)






U





Miocene M




L




Oligocene







Eocene


Stratigraphic unit


Unnamed quartz sands
Okefenokee Formation
Wicomico Formation


Miccosukee Formation







Jackson Bluff Fm.



Hawthorn Formation




St. Marks Limestone



Suwannee Limestone







Crystal River Fm.


west

0-80'




0-20'







0-20'



0-30'




0-230'







?1


Thickness

north

absent




50-100'







absent



30' 80'




0-120'



100-200


south

0-30'




absent







absent



absent




0-90'



0-200







?


General
lithology


Loose quartz
sands with
infrequent clays


Poorly sorted
fine to coarse
yellow orange
quartz sands,
silty and clayey



Sand, gray, ar-
gillaceous, very
macrofossiliferous

Phosphoritic
sands, silts,
clays, and sandy
limestones

White to yellow
orange, sandy
limestone

Yellow orange,
very fossiliferous,
very porous and
permeable lime-
stone containing
zones of dense
dolomite

Yellow orange,
very fossiliferous
partially recry-
stallized lime-
stone and It. tan
to It. brn. dolo-
mite, dense, re-
crystallized.


Water-bearing characteristics


Non-artesian aquifer, permeability
usually very good; supplies small
quantities of good fresh water to
rural domestic wells


Relatively impermeable clayey and
silty sands as confining layer on top
of Floridan aquifer; the lenticular
sands yield some water to shallow
dug wells. The limestones in the
base of the Hawthorn formation are
assigned to the Floridan aquifer.








FLORIDAN AQUIFER-almost all
wells in Leon County draw from the
limestones comprising this aquifer.
It yields water in large quantities of
good chemical character except for
local problems of iron.


I ill -1 r. - I








22 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

Table 3 lists the subsurface strata, their lithologies and water-
bearing characteristics.

PHYSIOGRAPHY

The United States has been divided into physiographic
provinces based on origin and physiographic expression of the
underlying sediments (Fenneman, 1938, p. 1-83). Fenneman placed
the Atlantic and Gulf coastal areas in the Coastal Plain Province,
and described them as a sequence of sedimentary strata laid down,
for the most part, in a marine environment, and limited to
formations of Cretaceous or younger age. He further divided the
Coastal Plain Province and placed North Florida in the East Gulf
Coastal Plain.
The physiography of Leon County has been discussed by
Sellards (1910, 1912, 1914, 1916, 1917), Harper (1910, 1914),
Cooke (1939, 1945), MacNeil (1949), Doering (1960), Puri and
Vernon (1964), and others. The early writers (Sellards and
Harper) discussed and described the red, sandy clay hills of the
northern portion of the county, and the sandy, lime-sink area
to the south, but they did not place names on these areas. Later,
Cooke (1939, p. 14) divided Florida into "five natural topographic
regions" and named each region. Cooke's Tallahassee Hills
encompassed the hilly area of northern Leon County, while the
generally lower sandy area to the south is placed in the Coastal
Lowlands.
On the basis of origin and age, Vernon (1951, p. 16) divided
the physiography of Florida into two primary groups (highlands
and lowlands), each of which he subdivided into two secondary
units. These secondary divisions are the Delta Plain and Tertiary
Highlands, and the Terraced Coastal and River Valley Lowlands.
He defined his highlands as sediments formed either as a part
of a high-level, widespread, aggradational delta plain or of Tertiary
land masses rising above this plain. He described his lowlands
as being formed by marine erosion and deposition along coastlines
and by alluviation and stream erosion along stream valleys. Vernon
proposed that where subdivisions of these secondary units are
mapped, local names may be appropriately applied.





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 23

The classification of the physiography based on origin and age,
as presented by Vernon, proves difficult in some application. For
example, the highlands area of northern Leon County is a broad
aggradational delta plain formed during Tertiary time. There-
fore, the restriction of an aggradational delta plain or a Tertiary
land mass presents a difficulty for classification. White (1958,
p. 9), in his report on the geomorphology of peninsular Florida,
presented similar objections to Vernon's usage. Vernon (personal
communication, 1963) agrees that strict adherence to his 1951
classification is not desirable, and has suggested a modification
is necessary to circumvent the above stated problem.
The physiography of Florida has been revised and described
in detail by White, Vernon and Puri (Puri and Vernon, 1964).
They continue the use of Highlands and Lowlands as primary
divisions, with their Highlands divided into the Northern
Highlands and Central Highlands, and their Lowlands divided
into the Atlantic Coastal Lowlands and the Gulf Coastal Lowlands.
They further subdivide these secondary groups into tertiary units.
The tertiary units applicable to Leon County are the Beacon Slope,
the Lake Munson Hills, and the Wakulla Hills. The distribution
of their landforms is shown as figures 5, 6, and 7 in Florida
Geological Survey Special Publication No. 5 (revised), 1964.
Based on physiographic expression, the authors recognize the
following major physiographic divisions in Leon County: 1) the
Northern Highlands, 2) the Gulf Coastal Lowlands, and 3) the
River Valley Lowlands.

NORTHERN HIGHLANDS

The Northern Highlands include the hills in the northern part
of the county that are immediately underlain by the Hawthorn
Formation and the Miccosukee Formation. They lie north of and
immediately adjacent to the lower Pleistocene coastal deposits.
Even though the elevations of some hilltops within the Highlands
area do not exceed those of the Coastal Lowlands, the area in
general is higher and more dissected than the adjoining lowland.
A distinct escarpment separates the areas, and the nature of the
surficial sediments within each area is characteristically different.
The Highlands of this report include only the Tallahassee Hills.





24 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

TALLAHASSEE HILLS

The Tallahassee Hills is a topographically high area in the
northern half of the panhandle area of Florida that is distinctly
different from the adjoining lowlands. Cooke (1939, p. 20-21)
first delineated and named the area and called it the Tallahassee
Hills. Hendry and Yon (1957, p. 10-11) followed Vernon's (1951,
p. 16) origin and age approach in delineating physiographic units,
and used his name Tallahassee Tertiary Highlands for the area.
Because the highlands are both Tertiary in age and deltaic in
origin, in this report, the unit is discussed only in terms of its
topographic expression and not in terms of origin or age. The
writers are adhering to Cooke's original terminology, the
Tallahassee Hills.
The Tallahassee Hills as described by Cooke (1939, p. 20)
". .lie between the Georgia State Line on the north and the
Coastal Terraces on the south-a width of nearly 25 miles-and
between the Withlachoochee River on the east and the Apalachicola
River on the west-a length of 160 miles." In Leon County, the
Tallahassee Hills extend from the Georgia State line on the north
to the Woodville Karst Plain on the south-a distance of about
18 miles, and between the Ochlockonee River on the west to the
Jefferson County line on the east-a distance of about 22 miles,
shown in figure 8.
The area is a Miocene-Pliocene delta plain surface that has
been dissected by streams and further modified by subsurface
solution. The resulting topography is characterized by erosional
remnant hills with relief up to 120 feet. The highest hills are
comparatively flat-topped with elevations of about 360 feet. The
slopes and crests of the hills give the over-all appearance of mature
topography that is gentle and moderate.
The hills are composed of a heterogeneous mixture of yellow.
orange clays, silts, and sands that are weakly cemented. In
roadcuts and excavations, these plastics resist erosion and may be
seen for years standing in nearly vertical cuts. The loamy soils
developed on the hills support a lush natural vegetation, and the
impermeable nature of the sediments give rise to small wet
weather ponds and lakes in the lower areas.






R5W + R4W R3W R2W R W R IE R R2E R3E
EXPLANATION G E O R G I A
HIGHLANDS o
f[-TALLAHASSEE HILLS 7
z liiK Lake lamonia Basin z
Lake Jackson Basin a i.
I Lake Lafayette Basin '
+ Lake Miccosukee Basin 4
LOWLANDS o.
SAPALACHICOLA COASTAL LOWLANDS c
z, Okefenokee Dunes I z
L I WOODVILLE KARST PLAIN
Lake Munson Hills ,z
iij Wakulla Sand Hills
S OCHLOCKONEE RIVER VALLEY LOWLANDS
ST. MARKS RIVER VALLEY LOWLANDS


C U N LOCATION OF GEOLOGY



W W RW W RW RE






50 1 2-3 04 551 M s
SD OLLAHASSF CONSERVATION


,..LEON COUNTY 0
1.5.0.. 3 4




C 0 U N T Y DIVISION OF GEOLOGY ci
R5W 4 R 4W 5R 3W R R2W R RIW R IE R2E R3E


Figure 8. Physiographic subdivisions in Leon County.





26 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

There exists within the Tallahassee Hills of Leon County three
large lake basins and a portion of a fourth which is shared with
Jefferson County. These basins drew the attention of early geologic.
-investigators, the most comprehensive of which is by Sellards
(1910, 1914). The authors describe these basins on pages 36-46.
The southern terminus of the Tallahassee Hills is abruptly
separated from the adjoining lowlands by a distinctive escarpment.
The elevations of the highlands along the escarpment are slightly
lower than those inland. This is due to more excessive surface
erosion along the fringe of the highlands than inland, where the
drainage is predominantly subsurface.
This escarpment has relief up to 100 feet, and on a clear day
the St. Marks Lighthouse, approximately 20 miles to the south,
may be seen from a position on top of the scarp. Vernon has
named this escarpment the Cody Scarp (Puri and Vernon, 1964,
fig. 5).
The western edge of the Tallahassee Hills in Leon County is
bounded by the Ochlockonee River Valley Lowlands. Eastward,
these highlands pass into northern Jefferson County.



GULF COASTAL LOWLANDS

The Gulf Coastal Lowlands cover the southern half of Leon
County and include the area that was affected by Pleistocene1
erosion and deposition. Throughout the Pleistocene Epoch there
was cyclic eustatic adjustment in sea level to the several build-ups
and melting of the polar ice caps. Cooke (1939, 1945) proposed
that during each glacial stage the ocean levels dropped and the
seas receded from the land; whereas, during the interglacial stages
the sea level rose and the seas advanced upon the land.
Each advance of the sea produced a gently seaward-sloping
plain called a terrace, and each terrace is separated from the
adjoining higher and older one by a seaward facing erosional
escarpment. A popular concept among Pleistocene coastal-plain
investigators is that the highest level of the seas occurred during
the earliest part of the Pleistocene Epoch, and each succeeding
high stand of the sea level was lower than the previous one. This
concept allows for the formation of younger terraces without
destroying the older ones.
Cooke (1939, 1945) has proposed at least seven interglacial
marine terraces along the Atlantic and Gulf coasts of Florida.





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 27

Vernon (1942, 1951) recognizes four interglacial marine terraces
and a high-level deltaic plain, and MacNeil (1949) recognizes
three interglacial marine terraces and one post-Wisconsin
interglacial marine terrace.
Two of the marine terraces recognized by Vernon are present
in Leon County. These are the Wicomico (100-foot) and the
Okefenokee (150-foot). Table 4 shows the correlation of terraces
of this report to those of Cooke, Vernon and MacNeil.
For the most part, the Gulf Coastal Lowlands area is composed
of light gray to buff colored loose quartz sands that lie at lower
elevations than the yellow orange poorly cemented sandhills to
the north. The Coastal Lowlands area is readily divisible into two
major units that are herein described and named the Apalachicola
Coastal Lowlands and the Woodville Karst Plain.

APALACHICOLA COASTAL LOWLANDS

The Gulf Coastal Lowlands area of Leon County is divisible
into two units based on topography. South of the Northern
Highlands area in the eastern half of Leon County is a low plain
underlain by a thin veneer of sand on a limestone bedrock. To the
west is another plain that is underlain by thick plastic deposits
and is a highlands when compared to the southeastern portion of
the county. Even though both of these units in southern Leon
County originated as a result of similar or even the same
environmental conditions of the Pleistocene Epoch, they should
be treated as separate physiographic units when based on
topography alone. The part that lies south of Lake Talquin and
to the west of State Highway 373 is a terraced plain that rises
from 90-100 feet at the Leon-Wakulla County line to about 150
feet at its northern edge (fig. 8). Though this southwestern portion
of the county is genetically related to the southeast portion, it is
a higher plain with different surface characteristics. This area
represents the marine plain of the Okefenokee sea. Because of
the thick and poorly permeable nature of the underlying sediments,
the area probably has not been lowered appreciably since
Okefenokee time.
The area has been published on by Wilder (1906), Harper
(1910), and Sellards (1913), and in these publications it has been
called the "Middle Florida Flatwoods" and the "Apalachicola
Flatwoods." Also, this area is within Cooke's Coastal Lowlands
and Vernon has named it the Beacon Slope, within his Gulf Coastal















TABLE 4. Correlation of Pleistocene Terraces.


COOKE
1939, 1945


Citronelle fim.

Brandywine, 270


Coharie, 215


Sunderland, 170


Wicomico, 100

Penholloway, 70

Talbot, 42



Pamlico, 25


VERNON VERNON MAC NEIL
1942 1951 1949


Delta Plain


220


150




105





30


Not present


Coharie, 220


Okefenokee, 150




Wicomico, 100





Pamlico, 25


Okefenokee, 150



Wicomico, 100





Pamlico, 25-35


THIS REPORT




? Miccosukee frm.
(Miocene Age)

Okefenokee Dunes


Okefenokee, 150




Wicomico, 100





? Pamlico, 25-35


PLEISTOCENE
STAGES


Early or pre-Nebraskan

glacial


Aftonian interglaciall)


Yarmouth interglaciall)




Sangamon interglaciall)



Mid-glacial sub-stage of

Wisconsin glacial stage





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 29

Lowlands (Puri and Vernon, 1964). The writers herein propose
the name Apalachicola Coastal Lowlands.
The Apalachicola Coastal Lowlands are characterized by
essentially flat, sandy surfaces marked by many shallow bays
(small densely wooded swamps) with few shallow, poorly defined
creeks. The area is underlain by sand and clay deposits up to
80 feet thick. The water table is very close to the surface, and
during the rainy season much of the area is swampy. Even
though the area is characteristically wet, the absence of lakes is
striking. Almost the entire area lies within the boundaries of the
Apalachicola National Forest. The usually wet nature of the area
plus the occupational restrictions now imposed by the National
Forest Service has left the area virtually undeveloped and
essentially in its natural state.
Across the northern edge of the Apalachicola Coastal Lowlands,
just south of and essentially paralleling State Highway 20 is a
low southward-facing escarpment (Cody Scarp) that occurs at
140-150 feet elevation. This escarpment probably represents the
Pleistocene-Okefenokee shoreline that is in evidence elsewhere
throughout the state (Vernon, 1951, p. 26; MacNeil, 1950, p. 101).

Okefenokee Dunes

To the north of this low escarpment and extending to the Lake
Talquin valley is a ridge of loose, quartz sands with considerably
more relief than is present in the Apalachicola Coastal Lowlands.
The highest elevations are about 170 feet. This ridge probably
represents the dune area associated with the Okefenokee shoreline
(fig. 8).

WOODVILLE KARST PLAIN

There extends from the southern edge of the Tallahassee Hills
to the Gulf of Mexico, a gently sloping, relatively low (0-60 feet)
plain. This plain is bounded on the west by the higher Apalachicola
Coastal Lowlands and extends eastward into Jefferson County
(fig. 8). It is characterized by loose, quartz sands thinly veneering
a limestone substrata that has resulted in a sinkhole-sand dune
topography. This area has previously been placed in the limesink
area of Harper (1910, p. 221; map opposite p. 204), and in the
Coastal Lowlands of Cooke (1939, p. 15-16). Harper (1914, p.
280-288) also recognized that the vegetation was considerably
different than that of the surrounding territory. On figure 5,





30 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

Florida Geological Survey Special Publication No. 5 (revised)
this area falls within the Gulf Coastal Lowlands. The writers
consider that the karst nature and relative lower elevation of
this portion of the coastal lowlands compared to the adjoining
Apalachicola Coastal Lowlands distinguish it as a distinct topo-
graphic unit, and it is herein named the Woodville Karst Plain.
In Leon County, the Woodville Karst Plain lies between 20 to
60 feet in elevation with the crests of dunes rising approximately
20 feet above the general level of the surrounding land. The
dunes are now quiescent and probably formed during a higher
stand at the sea when the area was free of vegetation. On the
Woodville topographic quadrangle there are topographic expres-
sions of barchan type dunes so oriented as to suggest a prevailing
wind from the northeast to the southwest.
The porous and permeable veneering sands have permitted
rain water to rapidly move into the underlying limestone strata.
These limestones are very soluble and have undergone considerable
solution by the action of these percolating ground waters. As
a result of this action, the area has been continuously and rapidly
lowered from its original level, and is presently covered with sinks
that appear as shallow sand-filled depressions. Sellards (1910, p.
50-52), has calculated that carbonate bedrock may be lowered at
the rate of one foot per five to six thousand years. This concept
of solution of the bedrock also has been used by Vernon (1951,
p. 42), White (1958, p. 9-44), and Yon and Puri (1960, p. 680),
to explain discrepancies in elevation of adjoining geologically
related physiographic units.
The higher, well drained, relatively non-organic, unconsolidated
quartz sand areas support a vegetation composed chiefly of pines,
black-jack and turkey oaks. In the lower wet areas, there are
cypress and bays. Harper (1914, p. 282-287) lists 30 species of
trees, seven species of woody vines, 30 species of shrubs, and 109
species of herbs within the area of the Woodville Karst Plain.
Since most water that falls on the area or enters as streams
from outside the area immediately disappears into the subsurface,
few surface streams have developed or exist. There are some
streams that wind their way for short distances and then disappear
into sink holes. The 15, 20 and 25-foot contour lines on the
Woodville topographic quadrangle delineate an elongated, mean-
dering valley that originates at the foot of the Cody Scarp in
section 35, T 1 S, R 1 E and joins the St. Marks River just south
-of the Leon-Wakulla County line. This valley is marshy in part





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 31

during the wet seasons, but does not contain a stream. It strongly
resembles the course of a stream that was probably captured
by subsurface drainage. The course of another pre-existing stream
can be traced on the Arran and Tallahassee quadrangles from the
Lake Bradford-Lake Munson area southward to its junction with
the Wakulla River just below Wakulla Springs. The one stream
that has perennial flow is the St. Marks River, which is located
in the eastern edge of the area. The base of the channel of the
St. Marks River is incised into the bedrock, and in the southeastern
corner of the county it disappears into sink holes and reappears
as springs several times, giving rise to a series of natural bridges,
as shown in figure 9.
There occurs along the northern and western borders of the
Woodville Karst Plain, areas of more prominent sand hills which
contain small lakes. The northern sand hill strip, about two miles
wide, lies adjacent to the Cody Scarp, and is included in the
Woodville Karst Plain area on figure 8. The relatively impermeable
plastics of Middle Miocene Age extend as an apron beneath the
loose permeable overlapping Pleistocene sands, thus providing them
with a relatively impermeable substrata. This substrata has
retarded the solution of the shallow underlying bedrock, and also
has created impermeable bottoms to small basins which retain
water as lakes.

Lake Munson Hills

The forty square-mile strip at the western edge of the Woodville
Karst Plain, even though similar in character to the remainder of
the plain, has a general land surface about 30 to 50 feet higher
than that to the east. The elevation of the crests of the dunes
and bars are 80 to 100 feet. Also, in this higher western portion
the lakes are numerous, essentially circular, and of the sink-hole
type, which do not exist elsewhere in the Woodville Karst Plain.
This area is shown on figure 8 as the Lake Munson Hills.
The silts and clays that are present in the subsurface of the
Apalachicola Coastal Lowlands area interfinger with the sands of
this western portion of the Woodville Karst Plain. This has
resulted in poorer permeabilty and a more restricted downward
percolation of the ground water with resulting less solution of
the bedrock than is found in the eastern portion of this unit.
Thusly, the elevation of the surface has remained more nearly at
its deposition level.





32 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN


-j_'. // | !K Y "2 (y
L TCO
AC A





Figure 9. A portion of the Woodville topographic quadrangle showing
the Natural Bridge area, in section 29, T 2 S, R 2 E.

The attitude of the bedrock, the increased thickness and less
permeable nature of the plastic overburden, and the higher
elevation of the area leads the writers to believe that this western
portion of the Woodville Karst Plain more nearly represents the
original depositional surface and elevation of the Woodville Karst





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 33

Plain, and probably is the offshore bar area related to the Wicomico
:;and of the sea. The shore line of the Wicomico Sea would be
L the base of the escarpment at the northern limits of the area,
nd near the 100-foot elevation in the western limits of the area.
because this area is prominent physiographically the writers
lave named it the Lake Munson Hills.

Wakulla Sand Hills

There exists in the southern edge of Leon County immediately
adjacent to the St. Marks River a series of dunes that very
probably are associated with the Pamlico shore line. Even though
the Pamlico shore line is not in evidence within the county, it is
present within one to two miles south of the Leon-Wakulla County
line. These hills reach 50 feet in elevation, and extend southward
into Wakulla County to the Pamlico shore line. The writers have
called this area the Wakulla Sand Hills.

RIVER VALLEY LOWLANDS

The River Valley Lowlands of this report include the streams
and stream valleys of the Ochlockonee and St. Marks rivers. The
area along each river is narrow, and because of the nature of the
sediments through which each flows, the valleys are different.
There is a striking similarity in stream course direction for all
streams in this part of the state. The Flint-Apalachicola system,
to the northwest, the Ochlockonee and the St. Marks of Leon
County, and the Aucilla River to the east all flow in a north-
northeast to south-southwest direction. These course directions
are probably associated with regional fracturing as reflected by
the lineations which are discussed on page 97.

OCHLOCKONEE RIVER VALLEY LOWLANDS

The Ochlockonee River Valley Lowlands is the area included
in the flood-plain terraces of the Ochlockonee River (fig. 8). These
lowlands are usually well delineated by both the nature of the
sediments and by fluvial escarpments that separate it from the
Tallahassee Hills. Near the Florida-Georgia State line, the
Ochlockonee lowlands is about two miles wide. Just north of the
upper end of Lake Talquin the fluvial sediments assigned to the
Ochlockonee River are in excess of three miles wide. In this area
the divide is very low between the Ochlockonee Valley and the





34 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

area of drainage on the south side of the divide, where the drainage
flows southward through the Lake Bradford-Lake Munson area.
These conditions suggest that a stream formerly flowed through
this area to the south, and the wider Ochlockonee Valley at this
point may represent a portion of the valley of this former stream.
Within the area of Lake Talquin, the valley is one-half to one mile
wide, the valley walls are steep, and the lake level is about 100
feet below the tops of the hills. The lake now occupies almost the
entire flood plain and no terraces are in evidence.
The Ochlockonee River Valley above Lake Talquin has two
well defined stream terraces that occur at 10 and 40-50 feet above
the flood plain. There is a third at 90-100 feet that is less well
defined.
On the Gadsden County side of the Ochlockonee Valley, the
surface slopes more gently toward the river than on the Leon
County side. Though the terrain rises relatively abruptly on the
Leon side, there are few bluffs as are found on the south and east
side of the Flint-Apalachicola system.

ST. MARKS RIVER VALLEY LOWLANDS

The St. Marks River Valley Lowlands heads up in the Talla-
hassee Hills area of eastern Leon County. It trends south-southeast-
ward through a portion of Jefferson County and then back again
into Leon County in a southwesterly direction to its juncture with
the Wakulla River valley just west of the town of St. Marks (fig.
8). This lowlands is the narrow, usually poorly perceptible, flood
plain valley of the St. Marks River since no fluvial terrace surfaces
are perceptible above the modern flood plain. The stream flows up-
on or slightly incised into bedrock, and the very thin veneer of
loose quartz sands that overlie the bedrock do not provide for well-
defined banks or a delineated flood plain. Because the water table in
the Leon County area of the St. Marks River isusually very high,
the river flows through a swampy terrain. The gradient normal
to the river course from the river channel to an elevation high
enough to be above the swampy condition, is about five feet per
one-quarter to one-half mile. The outline of the St. Marks River
Valley Lowlands on figure 8 is drawn at the higher limit of the
swampy area.
About three-quarter's mile above the Leon-Wakulla County
line the St. Marks River disappears into sinks and reappears as
springs several times, and the area is known locally as "Natural
Bridge" (fig. 9). South from this point, the St. Marks River





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 35

flows into a well-defined channel cut into bedrock and the St. Marks
River Valley Lowlands is readily discernible.
Sellards (1917, p. 133-135) proposed that the St. Marks
drainage system may have at one time included the Miccosukee
Basin and the Lafayette Basin. He shows the drainage system
for the Lafayette area, the Miccosukee area, and the St. Marks
River as it exists today, and also the reconstructed system as it
may have existed at an earlier stage of development. The St.
Marks River Valley Lowlands of this report is intended to
include only the St. Marks River system as it exists today.

MAJOR STREAMS

Leon County is characterized by many solutional depressions
that usually contain water as small ponds or lakes. Commonly
there are small streams of relatively short length that empty into
these ponds and lakes. These small streams have dendritic
patterns, and their upper reaches may be dry except during and
for a short period following the rainy season. The tributaries to
the Ochlockonee River in the Lake Talquin area have trellis
rather than dendritic drainage patterns. There are only two
streams of any consequence in Leon County, the Ochlockonee River
and the St. Marks River.

OCHLOCKONEE RIVER

The Ochlockonee River is the largest river in the county. This
river heads up in Georgia and flows southward to its junction
with the Gulf of Mexico in southwestern Wakulla County. It forms
a common boundary with Gadsden and Liberty counties along the
western side of Leon County. The stream is mature with numerous
meanders and meander scars. It's gradient from the Georgia State
line to the southwestern tip of Leon County is 1.5 feet per mile.
The stream has been dammed just upstream of the State
Highway 20 bridge for hydroelectrical purposes. Within the reach
of the dammed portion (Lake Talquin), the stream valley is
narrower and steeper than elsewhere along its course.

ST. MARKS RIVER

The other major stream within the county is the St. Marks
River. The river heads up in the Tallahassee Hills area of eastern
Leon County. From the Natural Bridge area northward, its flow
is small and the stream flows in a channel cut through a thin





36 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

veneer of sand which overlies the limestone bedrock. Below
Natural Bridge, the stream widens and its flow is increased
because of the additional water added by springs. The gradient
in Leon County is 2.5 feet per mile.
There are other streams in the county, but these are either
small brooks or are only wet weather overflow routes for excess
water.

LAKES AND LAKE BASINS

There are numerous lakes in Leon County, ranging from a few
acres to thousands of acres in area. Some of the lakes occupy
shallow depressions and exist only during the rainy season, while
others have basins deep enough to contain water the year round.
There are still others that normally have water, yet at times drain
completely in a relatively short time. Of the three larger physio-
graphic units within the county, only the Tallahassee Hills and
the Woodville Karst Plain contain lakes (fig. 8). Both large and
small lakes are found in the Tallahassee Hills area, whereas, only
smaller lakes are present in the Woodville Karst Plain. The most
striking comparative feature of the lakes is that all the larger
lakes are shallow, whereas the deeper ones are small in surface
area. These small deeper lakes are sink depressions that exist
well into the underlying limestone. The majority of the land area
of the Apalachicola Coastal Lowlands is relatively flat and poorly
drained, giving rise to a marshy or swampy type terrain, but the
area is devoid of lakes and lake basins.
Sellards (1910, p. 43-76) contributed substantially to the
understanding of lakes in Florida and particularly in Leon County.
His concept of the formation of the large basins in which occur
lakes lamonia, Jackson, Lafayette and Miccosukee was that they
were formed by the solution of the underlying limestone. Since the
basins of lakes lamonia, Lafayette and Miccosukee are elongated
and have a low end, Sellards noted that they appeared to represent
the enlarged valleys of what were originally small streams. He pro-
posed that along the stream courses the formation of sinks had en-
larged the valleys into broad basins. These sinks formed when the
piezometric surface was below land surface. Because of the sink
activity, the valley floors had been lowered below the level of the
mouth of the former streams and water draining into the basin was
retained. Water does drain from the lakes when (1) the level of the
lake exceeds that of the elevation of the former surface outlet, and




GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 37

(2) through sinks within the basin that periodically have open
connections to the underlying bedrock.
Little more was done on the origin of lakes and lake basins
until 1958 when White (1958, p. 65-90), in his work on the
geomorphology of peninsular Florida, took issue with Sellard's
concept of basin origin. White proposed that the large lake basins
were formed during a time when the piezometric surface was
higher than the area occupied by the lakes. Instead of a
development of cavities in the bedrock by the movement of ground
water and the subsequent formation of sinks that resulted in basin
enlargement, he states there was horizontal movement of ground
water through the insoluble plastics that overlay the soluble
limestone. In the process of this horizontal movement through the
insoluble plastics, the ground water dissolved the upper surface
of the more soluble portions of the limestones and formed the
lake basins. In contrast to Sellard's concept, White stated that the
sink-hole phase is the end or destruction phase of the lake basin
cycle. The longitudinal axes of the lakes do suggest that the
regional fractures in the bedrock (see p. 97) are closely related
to the formation of the lake basins.
Whether the larger lake basins in Leon County were formed
by sink-hole dismemberment of former stream valleys as Sellards
proposed, or whether this sink hole action is the final act of
destroying the previously existing lakes as White stated, is to the
writers, problematical. The contributions made in this report are
refinements on the stratigraphy, presentation of maps on the
configuration (see p. 64, fig. 17) and age determination of the
bedrock surface in the vicinity of the lake basins.
These large lakes in Leon County have periodically disappeared.
This disappearance is caused by a combination of low rainfall,
evaporation, and sinks that serve as drains. The basins are large
in area, have level bottoms, and usually are very shallow. This
readily permits large quantities of water to be lost to evaporation.
When this evaporation plus the volume lost into a draining sink
hole exceeds the inflow which is supplied by rainfall, the lakes
disappear.
There have been dams constructed across the drains leading
into these active sink-hole areas in order that no more surface
water be lost in this manner. This has provided a check to one
of the basic causes of water loss, but insufficient rainfall and
evaporation are contributing factors that still plague the existence
of these beautiful lakes.





38 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

LAKE IAMONIA
Lake lamonia is located in the northern portion of Leon County
within the Tallahassee Hills area (fig. 8). The lake lies in an
east-west trending basin that is approximately twelve to thirteen
miles in length and irregularly varying from less than one-half
mile to one and one-half miles in width. The greatest width is
in the western half of the basin. Though the eastern one-third to
one-half of the basin is now called Foshalee Slough and Foshalee
Lake, the entire basin has historically been called Lake lamonia
and this name is herein applied to the entire basin.
The lake is flat-bottomed and normally very shallow, with a
surface elevation of 90-100 feet. The elevation of the highest
hills in the immediate vicinity of the basin is about 220 feet. The
western end of the basin joins the flood plain of the Ochlockonee
River and during flood stage of the river there may be flow into
the lake basin. There are a number of small intermittent streams
that drain into the basin from the surrounding hills.
The basin has many sinks along its borders, most of which
are plugged with sediment. However, some of these sinks are
plugged with organic debris that, occasionally breaks free fol-
lowing drought conditions and leaves an effective drain. A large one
near the north-central shore has periodically become unclogged and
drained the lake basin, as shown in figure 10. The piezometric sur-
face in the vicinity of the lake lies about 20 feet beneath the bot-
tom of the basin.

LAKE JACKSON
Lake Jackson occupies a large angular basin in the west-central
part of the Tallahassee Hills area of Leon County (fig. 8). The
lake is roughly shaped like a capital "L" that is turned 45 degrees
clockwise. It is about 10 miles from tip to tip, and irregularly
one-half to two miles in width. The level of the lake is 85-95 feet,
and the elevation on top of the immediately surrounding hills is
220-230 feet. There are a few sinks at or near the perimeter of
the basin and during times when the basin has been dry (Sellards,
1910, p. 56) sinks have been observed in the central portion of the
basin. Figure 11 is a photograph that shows a very low stage
of the lake. There are a few wet weather creeks that drain into
the lake.
The two linear trends of the lake basin are parallel to the two
systems of surface lineations (Vernon, 1951, p. 47) that are so
common in Florida (see p. 98).





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 39


Ltz"


V


'


Figure 10. Lake Iamonia "sink." Locality LLn-3N-1E-23-bb. Top-stage
during 1931; bottom-stage during 1932.


..;.<


































Figure 11. Meginniss Arm of the Lake Jackson Basin during the low water stage.





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 41

At the southwestern corner of Lake Jackson, where the railroad
and U. S. Highway 27 cut across the basin, the divide between the
Ochlockonee River flood plain and the lake basin is only about 130
feet in elevation. This is not as low as the western end of Lake
lamonia. It seems apparent, however, that this low area may
have at sometime in the past been an overflow or drain. The
piezometric surface in this area is 25-40 feet in elevation.

LAKE LAFAYETTE

Lake Lafayette is located in east-central Leon County,
extending from the eastern edge of Tallahassee nearly to the Leon-
Jefferson County line (fig. 8). The basin is elongated in a west-
northwest to east-southeast direction. It is about six miles long
and one-quarter to one-half mile wide. The elevation of the basin
bottom is 30 to 40 feet and the elevation of the crests of the
highest surrounding hills approach 170 feet. At the eastern end
of the lake an arm extends from the main basin in a northwest
direction for about two miles. The lowest part of the basin is the
western end where several large sinks have developed. During
periods of excessive rainfall, water moves from this basin into
poorly defined streams that are tributary to the upper reaches
of the St. Marks River.
The eastern end of the basin is swampy and overgrown with
cypress trees. The western portion of the basin is normally dry
except where dams have artificially captured the flow from the
small stream that intermittently flows down the basin. There is a
large sink hole along the northern edge of the basin near the
western end that has captured much of the water in the lake
in the past. It has recently been dammed off, and the water level
in the sink stands at or just below the basin bottom and represents
the piezometric level in the area.
The lower arm of Lake Jackson is aligned with the trend of
Lake Lafayette. The structure maps drawn on the top of the St.
Marks and Suwannee limestones (see p. 61 and 64, fig. 16 and 17)
exhibit a trough along this same alignment.

LAKE MICCOSUKEE

Lake Miccosukee is located at the northeastern edge of Leon
County. Even though it lies within Jefferson County, its western
shore line marks the county boundary, and the upper drainage
area extends into Leon County (fig. 8). The lake basin is about





42 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

six miles long and two to three miles wide. The bottom of the basin
is at an elevation of 80-90 feet and the surrounding highlands rise
to about 160 feet. The north arm of the lake basin that extends
into Leon County is three to four miles in length and is dry except
during very rainy weather. The upper reaches of the basins of
lakes lamonia and Miccosukee (section 13, T 3 N, R 2 E) are
separated by a divide only about one-fourth mile wide.
At the lower end of Lake Miccosukee, excess high water flows
into an ill-defined creek known as Miccosukee Drain. This drain has
several active sinkholes that capture this excess water from the
lake. Topographically, the drain connects to the upper reaches of
the St. Marks River, and along this intermittent drainage course
Sellards (1917, p. 133-135) postulated the Miccosukee Basin and
the St. Marks River were at one time actively connected.
The piezometric surface in the Miccosukee area is between
50-60 feet in elevation. In the northwest section of the basin, on
the Leon County side, is a large sink that has actively drained
the lake in the past. This sink was dammed off in 1955 and no
longer receives surface water from the basin, as shown in figure
12. Water stands in the sink at the piezometric surface.

LAKE TALQUIN

Lake Talquin is a man-made lake created by the Florida Power
Corporation dam which is located on the Ochlockonee River at the
junction of Gadsden, Leon and Liberty counties (fig. 8). This
locality is known as Jackson Bluff and is a famous Upper Miocene
shell locality. The lake is about 15 miles long and one-half to one
mile wide. The water level, controlled by the dam, is about 69
feet in elevation. The valley that the lake occupies trends in an
east-northeast to west-southwest direction, and the elevation of
the bordering hills is up to 180 feet.
Lake Talquin, fed by the Ochlockonee River, as well as
numerous perennial but small tributary streams from both Gadsden
and Leon counties, is one of the most popular lakes in the area
for fishing and summer residences.

LAKE BRADFORD

Lake Bradford is a small lake located a few miles southwest
of Tallahassee in the northwest area of the Woodville Karst Plain
(sections 8, 9, 16, 17, T IS, R 1W). The lake is about 165 acres
in area, and receives its water from local rainfall and from a small





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.... .- > ---
r Iz;




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Figure 12. Lake Miccosukee basin during the low water stage in 1957.
Dam cuts off drainage into large sinkhole on northwest shore of lake. 0

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44 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

stream that enters from the northwest. This tributary stream is
known as Bradford Brook, and along its course are numerous sinks
that actively take water. During the dry season, the drainage into
Bradford Brook from the surrounding hills is completely captured
by these sinks, and no water drains down the brook run into Lake
Bradford.
Along the northeast edge of Lake Bradford is a high-water
drain, whose gradient is southward into Lake Munson. The bottom
of the lake basin is about 25 feet in elevation and the area
surrounding the lake is up to 60 feet in elevation. Homes of year-
round residents surround the lake, and the Florida State University
has a large recreational installation there.
Lake Bradford became very low in 1954-55, exposing almost
the entire basin, as shown in figure 13. The silt and organic
material on the bottom of the basin dried into large polygonal-
shaped blocks separated by a good example of mud cracks, seen in
figure 13. During this dry period several small sink holes formed
on the southeastern shore of the lake at about the normal water
level.
Heading up very near the upper end of Lake Talquin is a small
poorly defined intermittent stream that joins the Lake Bradford-
Lake Munson drain. The divide between it and the small tributary
streams to the Ochlockonee River is less than 10 feet high. It is
possible to trace an active drainage area from this low divide,
which is within 1 mile of the Ochlockonee River, to a point several
miles south of Lake Munson. An abandoned stream channel is
apparent on the topographic maps from that point to its junction
with the Wakulla River just downstream from the spring. As
previously suggested, this may represent a former course of the
Ochlockonee River.

LAKE MUNSON

Approximately two and one-half miles southeast of Lake
Bradford is located Lake Munson (sections 26, 27, T 1S, R 1W).
This lake is an enlarged portion of the surface drainage south from
Lake Bradford. It is in excess of 270 acres in area with a surface
elevation of 20-30 feet. The surrounding terrain very gently slopes
upward to elevations of about 50 feet.
Southward from the lake is a stream meander scar that can be
traced on the Arran and Tallahassee topographic quadrangles to
its junction with the Wakulla River, just south of Wakulla Springs.





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td


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0





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Figure 13. Lake Bradford basin during the low water stage, May 10, 1955,
including view of Florida State University dock (note mud cracks).





46 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

LAKE HALL

Lake Hall is located in the Tallahassee Hills about three miles
east of Lake Jackson (section 5, T 1 N and sections 32, 33, T 2 N,
R 1 E). It is a small lake, about 300 acres in area, and is at the
head of a small valley that joins with Lake Jackson. The popularity 1
of this lake comes from McClay Gardens, a State Park, located on
the shores of the lake, which is one of the most beautifully
landscaped parks in Florida.

OTHER LAKES

Other small named lakes within the Woodville Karst Plain that
are similar in occurrence to Lake Bradford and Lake Munson are
Silver Lake (elev. 75 feet), Moore Lake (elev. 95 feet), Dog Lake
(elev. 65 feet), and Dog Pond (elev. 85 feet). The piezometric
surface in this area is about 20 feet above sea level. All of these
lakes occur in the western part of the Woodville Karst Plain
within the Lake Munson Hills.
Lakes Erie (elev. 25-30 feet), Mattie (elev. 35 feet), Mary
(elev. 40-45 feet), Twin Lakes (elev. 40-45 feet), Homer (elev. 40
feet), Eagle (elev. 20-25 feet), Turf Pond (elev. 20-25 feet), and
Bonnet Pond (elev. 20-25 feet) are a group of small lakes in the
northeastern portion of the Woodville Karst Plain at the southern
edge of the Tallahassee Hills. The level of these lakes represents
the piezometric surface except for Twin Lakes, Homer Lake, and
Lake Mary which appear to be perched upon an apron of relatively
impermeable plastics of Middle Miocene Age.

STRATIGRAPHY

INTRODUCTION

The State of Florida is uniquely distinct both in its geographic
position within the North American continent and in its outline. It
lies at the extreme southeastern corner of the continent and
projects seaward as an elongated peninsula. This peninsula is the
emerged portion of a greater mass of sediments known as the
Floridan Plateau (Vaughan, 1910, p. 107). Leon County is located
along the north central border of the Floridan Plateau.
The sediments composing this plateau range in age from early
Paleozoic to Recent, and vary in thickness from about 5,000 feet
in the central peninsula to more than 15,000 feet in south Florida.





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 47

Pre-Paleozoic crystalline rocks have been encountered in wells
drilled on the Plateau. However, no wells within the Big Bend
area of Florida have penetrated this sequence. In this area, the
oldest rocks encountered have been sedimentary rocks of Silurian
and/or Ordovician age at depths of about 7,000 feet.
There are about 4,500 feet of Mesozoic clastics and carbonates
in this area, and the Tertiary is represented by 2,500 feet of
carbonates, sands, and clays. The Quaternary beds are composed
of sands and some sandy clays, and are less than 100 feet thick,
as seen in table 5.

PALEOZOIC ERA

ORDOVICIAN SYSTEM

Beds of Lower Ordovician Age (?)

Sedimentary rocks of Paleozoic Age have been penetrated by
numerous wells in Florida (Applin, 1951). Applin (1951, p. 2)
depicts an area that includes Leon County as being underlain
by Silurian and Ordovician sedimentary rocks. However, no well
in Leon County has been drilled deep enough to encounter rocks
older than Early Cretaceous Age. Within the adjoining county
to the east, four feet of a quartzitic sandstone were penetrated at
a depth of 7,909 feet in the Coastal Petroleum Company, E. P.
Larsh No. 1 well. Applin (1951, p. 23) listed this occurrence only
as Paleozoic in age, but later he (Yon, 1966, p. 33) tentatively
assigned these lower four feet to the Early Ordovician. Bridge
and Berdan (1952, p. 37) also date these four feet of quartzitic
sandstones as Early Ordovician.

MESOZOIC ERA

TRIASSIC SYSTEM

Beds of Upper Triassic Age

NEWARK (?) GROUP

No well drilled in Leon County has penetrated rocks of Triassic
Age, but since they are reported in wells both to the east and west
of the county, they are considered to exist beneath the entire
area. The Southeastern Geological Society Mesozoic cross-section
A-A' (Southeastern, 1949) is an east-west section through this






48 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN


TABLE 5. Stratigraphic nomenclature for geologic formations in Leon County,
Florida.


Series





Recent-
Pleistocene










Miocene






Oligocene


SUpper


Stage/Age














Choctawhatchee

Stage


Alum Bluff Stage


Tampa Stage





Jackson Age


Claiborne Age





Wilcox Age


Midway Age


Undifferentiated beds of Lower Cretaceous age,
composed of red, waxy shales, nodular lime-
stones and sandstones.


Newark ? Age


Beds of red, micaceous
shales and poorly sorted
sandstones and diabase
intrusives.



Unnamed quartzitic sand-
stone


Formation


Unnamed sands and clays


Pamlico dunes


Wicomico Formation


Okefenokee Formation


Miccosukee Formation


Jackson Bluff Formation


Hawthorn Formation


St. Marks Formation


Suwannee Limestone


Ocala Group


Avon Park Limestone


Tallahassee Limestone


Undifferentiated beds


Undifferentiated beds


Beds of Taylor age


Austin Chalk


Atkinson Formation


Middle





Lower


Paleocene




Gulf






Comanche


Upper


Lower





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 49

area and shows sediments of probably Triassic Age at 6,810 feet
in the Coastal Petroleum Company, E. P. Larsh No. 1 well
(Jefferson County). Applin (1951, p. 15) placed the hard, red
micaceous shales and poorly sorted, fine to coarse-grained
sandstones that are present in this well in the Triassic System.
Within these Triassic shales and sandstones, he (Applin, 1951,
p. 26) listed igneous intrusives in the form of diabase and related
kinds of volcanic rocks. These occur from 7,763 to 7,792 feet and
7,850 to 7,890 feet. Later, Applin (1957, p. 1486-1489) placed the
rocks at 7,030 feet in this well in the Upper Triassic-Newark Group.

CRETACEOUS SYSTEM

Comanche Series

UNDIFFERENTIATED BEDS OF LOWER CRETACEOUS AGE

In the Stanolind Oil and Gas Company, St. Joe Paper Company
No. 1-A well, in the southeastern corner of Leon County, there are
at least 2,230 feet (Applin and Applin, 1947, fig. 4) of rocks of
Early Cretaceous Age present from 4,290 to 6,520 feet. These
deposits are plastics composed of red-brown shale containing gray,
sandy limestone, and gray to greenish gray, micaceous sandy shale
interbedded with sandstone (Applin and Applin, 1944, p. 1722).
In the Coastal Petroleum Company, E. P. Larsh No. 1 well
in Jefferson County, approximately 3,000 feet of Lower Cretaceous
plastics were encountered from 3,836 to 6,810 feet (from electric
log) and in the Ravlin-Brown, Philips No. 1 well in northeastern
Wakulla County 1,476 feet were penetrated at 4,270 feet.

Gulf Series

ATKINSON FORMATION

The Atkinson Formation was named by Applin and Applin
(1947) for Upper Cretaceous beds that occur between the Austin
Chalk and the top of the Lower Cretaceous. These deposits were
previously referred (Appin and Applin, 1944, p. 1718) to the
Tuscaloosa Formation of the lower part of the Upper Cretaceous.
Because this interval is sufficiently different lithologically the
Applins (1947) considered it a different depositional unit and
subdivided it into three unnamed members. The upper and lower
members have been identified in southeastern Leon County. The





50 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

middle member is absent in this area, but may be present in
central and western Leon County (Applin and Applin, 1947, maps
no. 2 and 3).
The Atkinson Formation in the Stanolind Oil and Gas Company,
St. Joe Paper Company No. 1-A well is 790 feet thick. The upper
member occurs between 3,500 and 3,878 feet, and is represented
by a deeper water marine facies composed chiefly of marine shales
previously called the marine shales of the Tuscaloosa Formation.
In this well, the middle member is absent, but the lower member
is 412 feet thick, from 3,878 feet to 4,290 feet, and it is composed
of poorly sorted, fine to coarse, micaceous sand interbedded with
flaky red, gray, purple, varicolored or mottled shale.

AUSTIN CHALK

Beds of Austin Age occur beneath Leon County at a depth of
approximately 2,900 feet. In the Stanolind Oil and Gas Company,
St. Joe Paper Company No. 1-A well, there are 620 feet of shale,
marl and sands assigned to the Austin Chalk. The Austin interval
in Florida is represented by sand and shale to the west, grading
into shale and marly limestone in central Florida and limestone
in South Florida (Applin and Applin, 1944, p. 1715).

BEDS OF TAYLOR AGE

There are 260 feet of sediments that are assigned to the Taylor
interval in the Stanolind-St. Joe Paper Company No. 1-A well, in
Leon County. The top of this unit represents the top of the
Cretaceous in this area since the normally overlying Lawson
Limestone is absent. Applin and Applin (1944, p. 1713) assign
to the Taylor over 700 feet in the Ravlin-Brown Company, Philips
No. 1 well in northeast Wakulla County. The thinner section in
Leon County probably represents only the lower beds of the Taylor.
These sediments are composed of interbedded gray marl and
limestone and light gray, grayish to bluish green calcareous shale.
This interval has a distinctive character on the electrical log and
contains abundant fragments of Inoceramus sp.





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 51

CENOZOIC ERA

TERTIARY SYSTEM

Paleocene Series

UNDIFFERENTIATED BEDS OF MIDWAY AGE

The sediments assigned to the Paleocene Series were recognized
in two deep wells (WLn-2S-1E-11-cb and WLn-2S-2E-15-bb) in the
southeastern corner of the county. The upper part of these
deposits consists of a pale yellowish-green silty, slightly calcareous,
microfossiliferous, moderately soft clay. This grades downward
into a pale yellow orange, argillaceous, very microfossiliferous,
very slightly sandy and slightly glauconitic calcilutite.
In the Central Florida Oil and Gas Company, Rhodes No. 1
well (WLn-2S-2E-11-cb) the sample intervals are large; however,
from samples the interval assigned is from 2,530 to 2,640 feet.
The Stanolind Oil and Gas Company, St. Joe Paper Company No.
1-A well (WLn-2S-2E-15-bb) is sampled at 10-foot intervals, and
the Paleocene occurs from 2,490 to 2,620 feet. Applin and Applin
(1944, p. 1703-1708) have a good regional description of the
Paleocene in Florida and southern Georgia.



Eocene Series

UNDIFFERENTIATED BEDS OF WILCOX AGE

Lower Eocene beds of Wilcox Age have been identified in the
two deep oil tests in southeastern Leon County. In these wells
the sediments are composed principally of pale orange, soft,
argillaceous, slightly dolomitic, glauconitic calcilutite that contains
some interstitial gypsum and abundant brown chert. At the top
of the section a grayish green, soft, calcareous clay is encountered.
Some samples have an oolitic appearance.
In the Central Oil and Gas Company, Rhodes No. 1 well, these
deposits occur between 1,995 and 2,530 feet, and from 2,030 to
2,490 feet in the Stanolind Oil and Gas Company, St. Joe Paper
Company No. 1-A well. This unit has a poorly preserved fauna
in this area which Applin and Applin (1944, p. 1700) describe
as consisting mainly of several species of Globigerina and Globor-
otalia.





52 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

CLAIBORNE GROUP
LAKE CITY LIMESTONE

The Lake City Limestone was named by Applin and Applin
(1944, p. 1693) for the carbonate deposits of early Middle Eocene
Age that occur in North Florida and the peninsula. This formation
was identified in the Central Oil and Gas Company, Rhodes No. 1
well between 1,600 and 1,995 feet, and in the Stanolind Oil and
Gas Company, St. Joe Paper Company No. 1-A well between 1,614
and 2,030 feet. It is composed of pale orange, recrystallized,
microfossiliferous, very glauconitic calcarenite with noticeable
intergranular porosity. The texture is characterized by larger
crystals of calcite in a very finely crystalline to chalky matrix.
Also within the interval assigned to the Lake City Limestone there
occurs a dark yellow orange, sucrosic, crystalline, glauconitic
dolomite. Occurring as a minor part of the lithology, but very
distinguishable are gypsum and light brown chert.

TALLAHASSEE LIMESTONE

Applin and Applin (1944, p. 1688) named the sediments
of late Middle Eocene Age in the Big Bend area of Florida
the Tallahassee Limestone. They separated this unit from
sediments of upper Middle Eocene Age on the presence of a
microfauna not present in other parts of Florida and Georgia.
The Tallahassee Limestone is a cream and tan, crystalline lime.
stone, in part argillaceous with common chert and gypsum. In
Leon County, the Applins assign from 999 to 1,600 feet in the
Central Florida Oil and Gas Company, Rhodes No. 1 well, to the
Tallahassee Limestone. The writers examined this interval in
the deep oil tests in Jefferson, Leon, and Wakulla counties, an
were unable to discern enough lithologic difference to be able tc
separate the unit from the overlying Avon Park limestone.

AVON PARK LIMESTONE

The Avon Park Limestone was named by Applin and Appli
(1944, p. 1680, 1686) for deposits in Florida of late Middl
Eocene Age. There are no wells in Leon County that have goo
enough sampled intervals to accurately determine the tru
thickness of this unit; however, these sediments are identifiable
in all the deep oil tests in the area.





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 53

The Avon Park Limestone in the Leon County area is
composed of pale orange, moderately soft, granular, poorly porous,
microfossiliferous calcarenite in a silty to finely crystalline matrix
with coarser euhedral crystals of calcite or dolomite. Also
contained within this unit are zones or beds of dark gray to brown
chert and small amounts of selenite. Within the middle portion of
the unit the microfossils become large and robust, giving the
limestone a calciruditic texture. At least 600 feet of sediments
can be assigned to the Avon Park Limestone in the Stanolind Oil
and Gas Company, St. Joe Paper Company No. 1-A well.

JACKSON AGE
OCALA GROUP

The two deep tests for oil and gas that have been drilled in
the Leon County area are poorly sampled at best through the
Upper Eocene to Recent section. The better sampled of the oil
tests is the Stanolind Oil and Gas Company, St. Joe Paper
Company No. 1-A well, but even in this well there are large gaps
in the samples from the upper section. For this reason,
information on the lithology and thickness of these younger
deposits is unreliable in these wells. There are many water-supply
wells in Leon County that are reasonably well sampled, and a few
extend to depths that penetrate the Upper Eocene sediments
(table 2).

CRYSTAL RIVER FORMATION

Historical.-The Crystal River Formation was named by Puri
(1953a, p. 130) for Jackson Age limestone lying between the
underlying Williston Formation and the overlying Suwannee
Limestone. Excellent historical descriptions of this unit are
presented in Florida Geological Survey Bulletin Nos. 33 and 36,
and Special Publication No. 5, and will not be restated here.

Definition and distribution.-The Crystal River Formation is the
only unit of Jackson Age the writers have recognized in samples
from wells located within the county. The formation immediately
underlies the Oligocene Age-Suwannee Limestone.
Based on fossils, Jackson Age sediments have been reported
in the basal samples of several City of Tallahassee water-supply
wells by Cole (1945), Puri and Vernon (1959), Cole and Applin





54 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

(1961), and Cheetham (1963). In the City of Tallahassee well
nos. 6 and 8 (WLn-1N-1E-30-ac-1 and WLn-1N-1E-30-ac),
Cheetham (1963, p. 85) identified the Floridina antique zone,
Jackson Age Bryozoan, at -213 feet and -207 feet respectively;
Cole (1945, p. 17, 23) identified Helicolepidina paucispira, a
Jackson Age foraminifer in the City of Tallahassee well no. 6
(WLn-1N-1E-30-cc-1) at 404 feet (-217 feet) and in the Dale
Mabry well no. B (WLn-1S-1W-4-cb) at 308 feet (-219 feet).
In the Dale Mabry well Helicolepidina paucispira (Eocene) occurs
with Oligocene forms, and Cole (1945, p. 23) states that ".... these
specimens [Eocene and Oligocene forms] in the last sample were
in place and do not represent cavings from above." Later, Cole
(1961, p. 132) reports the presence of Helicostigina polygyralis
(synonymous with Helicolepidina paucispira) at these same
depths in these same wells. In a core hole (WLn-1N-1W-35-b)
located at the Florida Geological Survey office building in Talla-
hassee, from the interval at a depth of 271 to 276 feet (-171 to
-176), cores yielded Lepidocyclina yurnagunensis (Oligocene)
and Helicostegina polygyralis (Upper Eocene) together in abun-
dance. Dr. Cole (personal communication, 1964) has examined
this interval and states, "I would place this sample in the Oligocene
just above the top of the Eocene. . ." He also examined cores from
281-286, 300-306 and 313-316 feet, and :placed the 300-306 and
313-316 intervals in the Upper Eocene. The interval at 281-286
feet might possibly be Eocene, but because of very poor preserva-
tion of fossils, Cole could not be certain.
Puri (personal communication, 1963) has stated that Upper
Eocene-Crystal River and Oligocene-Suwannee forms are present
together in samples that have been taken from the Suwannee
Straits area, and that they may have been mixed during the
formation of the Straits. The Crystal River Formation was also
penetrated in well WLn-2N-3W-9-da at the eastern edge of Leon
County. Even though no wells have penetrated deep enough to
encounter Jackson Age sediments in western Leon County, it is
considered to be present there since it is identified in the deeper
tests for oil throughout the Big Bend area.
The older deeper wells have been worked by numerous
geologists and paleontologists, and frequently the key fossils have
been picked out of the samples. For this reason, and since this
stratigraphic break both lithologically and paleontologically is
sometimes obscured through dolomitization of the limestone,
gamma-ray logs were the best criterion to determine the top of





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 55

the Jackson Age sediments. The Eocene sequence on the gamma-ray
log depicts relatively less activity for this interval than for the
overlying Oligocene beds. Figure 14 shows several gamma-ray
logs of wells in the area that illustrate how this break serves to
facilitate correlation. Figure 15 depicts several cross-sections in
which the Upper Eocene sediments were penetrated by water-
supply wells.

General lithology.-The Crystal River Formation in Leon County
is composed of very pale orange, microcoquinoid, very porous and
permeable calcirudite, and grayish orange, recrystallized, very
dense dolomite, with some molds and casts of fossils. The unit, as
examined in well samples, is very similar in lithology to the
Suwannee Limestone. The dolomite is secondary, and the
dolomitization, for the most part, has destroyed the original
lithology.

Stratigraphic relations.-The Crystal River Formation is known
to unconformably underlie the Suwannee Limestone. The entire
Jackson unit is grouped in this report under the Crystal River
Formation, and these Upper Eocene sediments unconformably
overlie the Avon Park Limestone.

Thickness and structure.-None of the water-supply wells in the
county have been drilled completely through the Jackson section;
therefore, the thickness of this unit can only be estimated from
oil tests. In the southeastern part of the county, the thickness is
approximately 400 feet.
Limited data did not permit structural interpretations with
the exception of the large downwarp known as the Gulf Trough
in the western area of the county (Applin and Applin, 1944, p.
1729; and Herrick and Vorhis, 1963, p. 20) which the data does
complement.

Aquifer.-Only a few of the water-supply wells are deep enough
to penetrate into the Crystal River Formation. The zones within
it that have not been recrystallized to the extent of destroying
the porosity and permeability will yield large supplies of good
water. The chemical analysis of the water from the Crystal River
Formation is restricted to only one well, WLn-2N-3E-11-ca (see
p. 132), since it is the only well for which water essentially
from Jackson Age sediments could be obtained.





56 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN


Figure 14. Gamma-ray log of well WLn-2N-3E-11 ca, Leon County, showing
the relative difference in the radioactivity of the Upper Eocene and Oligocene
sediments.






GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 57




IV MICCOSUKEE FORMATION SOUTH
+zoo NORTH +200

+100oo / i +00oo



-1ooL SECTION A-A' -oo


+200/

+100-




--100-


SECTION B-B'


SECTION C-C'


4 ,A

Cr

---,- -:-f.--^.-


C
LOCATION OF CROSS SECTION


WEST / i S EAST
+300 +3o00
/ MICCOSUKEE FORMATION I ,MICCOSUKEE FORMATION I
+200 Ui +200

+100 H A WORMATION +100
II ------ ----------"i

SI ST. MA RKS F 0 RMATION
S0U-W SUWANNEE LIMESTONE

-looL SECTION E-E -100

Figure 15. Geologic cross-sections.


WEST
-1ooF



J A
0 "C





58 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

Oligocene Series
SUWANNEE LIMESTONE

Historical.-The Suwannee Limestone was named by Cooke and
Mansfield (1936, p. 71) for ". . yellowish limestone typically
exposed along the Suwannee River in Florida, from Ellaville . .
to almost White Springs . The writers think it is of late
Vicksburg age."
Very adequate historical summaries of the Suwannee Lime-
stone have been published in Florida Geological Survey Bulletin
Nos. 21, 29, 33, and therefore will not be discussed in this paper.

Definition and distribution.-The Suwannee Limestone is the only
deposit of Oligocene Age the writers recognize in Leon County.
It overlies the Jackson Age-Crystal River Formation and underlies
the Tampa Age-St. Marks Formation, and is continuous throughout
the entire county in the subsurface.

General lithology.-The Suwannee Limestone is a very pale orange,
abundantly microfossiliferous, granular, partially recrystallized
limestone (calcarenite) with a finely crystalline matrix. No
attempt was made to identify the entire fossil suite in the
Suwannee Limestone; however, certain genera are important and
will be mentioned. The upper section of the formation is
characterized by the genera Asterogerina and Rotalia. Lower in
the section the genera Dictyoconus-Coskinolina and Lepidocyclina
are predominant. Puri and Vernon (1959, p. 93) state "Species
of Lepidocyclina and Operculinoides are not present in the type
sediments [east of Leon County] and the Coskinolina-Dictyoconus
are not present in the panhandle. The two facies merge and both
are penetrated in wells in the Tallahassee area."
The Suwannee Limestone appears to be partially dolomitized
throughout the entire section, with the lower half showing an
increase in dolomitization over the upper half. The dolomitic beds
in the lower Suwannee have good continuity and can be traced
and correlated by electric logs and samples from wells. As
dolomitization and recrystallization increases, the quantity of
discernible fossil material decreases and locally may be totally
obliterated.
A relatively thin milky-colored chert zone is locally present at
the top of the Suwannee Limestone in the county. This cherti
contains microfossil ghosts, indicating a replacement of thel
limestone by silica. This presence of silica is a rather common





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 59

occurrence in the limestones of Florida, and its source is probably
from silica-laden ground water. It is likely that the silica in
solution in the ground water has been derived from clay, that is
one species of clay altering to another wherein silica is lost, and
,also perhaps from the disintegration of amorphous silica volcanic
glass within the sediments through which the water moves.
Probably very little is derived from the quartz sands (crystalline
silica) which is much less soluble than amorphous silica.
Conditions that could bring about precipitation of silica from
groundwater are not clearly understood. Normally, factors
controlling the precipitation of silica from solution are those
affecting the solubility of the silica, such as the hydrogen ion
concentration, temperature, and evaporation.

Stratigraphic relations.-Contact relationships with the Eocene
sediments could not be established from oil tests, and the number
of water wells that penetrated this interval are few; however,
the Oligocene is found to unconformably overlie the Upper Eocene
sediments where evidence is available (WLn-1N-1E-35-b, WLn-
1N-1E-30-cc-1, WLn-1N-1E-30-cc, WLn-2N-3E-11-da).
Since over 100 sampled water wells terminate in the Suwannee
Limestone in Leon County, there are good data to reveal the
distinct paleontological and lithological differences between the
Suwannee Limestone and the unconformably overlying St. Marks
Formation. The break between these two strata is readily
apparent in samples even though extensive dolomitization obscures
the contact in many places.

Thickness and structure.-In Leon County the Suwannee
Limestone is entirely a subsurface formation. Throughout most
of the county it is overlain by Miocene sediments, with the
exception of several small areas in the southeastern part of the
area and the Lake lamonia and Miccosukee basins where it is the
first bedrock encountered beneath the Miocene and Pleistocene
sands. In a water supply well (WLn-2N-3E-11-da) on the west
edge of Lake Miccosukee, the Suwannee Limestone is 185 feet
thick. This probably represents an incomplete section as the over-
lying St. Marks Formation has been completely removed by erosion.
In the Tallahassee area where some wells reach Jackson Age sedi-
ments, the Suwannee is up to 204 feet thick. A water well (WLn-
1S-2W-23-dd) about six miles southwest of Tallahassee, penetrated
Suwannee at 133 feet below sea level.





60 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

Several tests for oil in southeastern Leon County penetrated
through the Suwannee interval, but in only one (WLn-2S-2E-
15-b) are the sample intervals close enough to be reasonably sure
of the thickness. In this well, there can be assigned at least 190
feet to the Suwannee. In well WLn-2S-1E-11-cb, a sample at 665
feet contains Oligocene fauna with less than 100 feet of this 665 feet
being assigned to post-Oligocene sediments. In another oil test
(WWa-3S-1E-14-bc) drilled in Wakulla County just south of
Woodville, the first sample (400 feet) is Oligocene in age and the
top of the Eocene was picked by Cole (1945, p. 82) at 745 feet.
The thicknesses in these two wells appear to be excessive.
The elevation of the top of the Suwannee Limestone is highly
variable within the county, shown in figure 16, ranging from in
excess of 50 feet above sea level in the Lake Jackson area to 323
feet below sea level in the western part of the county (fig. 15).
In the Tallahassee area, wells encounter Oligocene sediments
from plus 30 to in excess of 100 feet below sea level.
Westward from the Tallahassee area, the surface of the
Suwannee slopes downward into the large northeast-southwest
trending Gulf trough. Within this trough, the elevation of the
Oligocene top is 323 feet (core hole WLn-1S-4W-21-aa) below sea
level at Jackson Bluff (fig. 15).
Eastward from Tallahassee, the surface of the Suwannee dips
gently southward at less than five feet per mile with an
approximate east-west strike. The surface of the Suwannee is
marked by irregularities, that, because of poor well spacing,
cannot be categorized. These irregularities may reflect faulting
or they may reflect erosional channels that are oriented along the
trends of the regional fracturing.

Aquifer.-The Suwannee Limestone in Leon County is generally
very porous and permeable. It is the principle aquifer and most
of the water-supply wells penetrate into the formation. Because
of its depth in the western section of the county, the Suwannee
is not used as an aquifer there.

Miocene Series

TAMPA STAGE
ST. MARKS FORMATION

Historical.-Sediments herein described as the St. Marks
Formation are stratigraphically equivalent to deposits originally













. Line showing top of the Suwannee Limestone,in feet,
referred to mean sea level.
Contour interval 20 feet changing at 100 feet to
100foot interval.


RSW R4W R3W


R2W RIW


R2E R3E


Figure 16. Structure map of Oligocene sediments.


z


I Ig I I I r r smF~


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


RSW


0
O
0
0

z



0
0










C/
0
ti

0









0
z





C17
0





z
H
M
Ui


I


RIE





62 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

named the Tampa Formation (Johnson, 1888) from the Tampa
Bay area. The term St. Marks Limestone was first used by Finch
(1823, p. 31-43), and applied to the impure limestones in and
around St. Marks, Florida. These deposits were subsequently
referred to as the Tampa Formation, with the term St. Marks
Limestone falling into disuse. Puri (1953, p. 20-21), in his study
of the Miocene of west Florida, revived the term St. Marks and
applied it to the calcareous facies of his Tampa Stage. More
complete historical summaries of the Tampa Age rocks and
terminology are presented in Florida Geological Survey Bulletin
Nos. 21, 29, 33, and 36.

Definition and distribution.-The deposits in Leon County assigned
to the St. Marks Formation are the sandy limestones that
immediately overlie the Oligocene-Suwannee Limestone, and
underlie the Alum Bluff Age-Hawthorn Formation or younger
sediments. The St. Marks Formation underlies most of the county,
and is essentially a subsurface formation, cropping out only in
a few sinks and where the thin veneer of Pleistocene sand is
absent in the southeastern portion of the county.

General lithology.-Sediments of the St. Marks Formation are
predominantly fine to medium grained, partially recrystallized,
silty to sandy limestones (calcilutites to calcarenites) that have
undergone degrees of secondary dolomitization. The color ranges
from very pale orange for the only slightly dolomitized portion.
to grayish orange for the highly dolomitized section. The St.
Marks Formation is normally 90% or more calcium carbonate,
however, locally it may be as low as 75%. Even though the
formation has been partially recrystallized and has a finely-
crystalline ground mass, it has an overall slightly chalky to earthy
appearance. The silt and sand content is composed of quartz and
is rounded to subrounded.
Microfossils are present in the St. Marks Formation, but they
are not usually common, and with the exception of the two genera
Archaias and Sorites, are seldom identifiable. Oysters and pecten
fragments are occasionally found in well cuttings.

Stratigraphic relations.-The St. Marks Formation unconformably
overlies the Suwannee Limestone. This unconformity is evidenced
by the distinct lithologic and faunal differences, and the highly
irregular top of the Suwannee Limestone. The contact with the
overlying Hawthorn Formation is also unconformable as evidenced





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 63

by the distinct lithologic differences. The Hawthorn Formation is
principally a plastic sequence with stringers and lenses of
limestone.

Thickness and structure.-The thickness of the St. Marks
Formation in Leon County ranges from 0 feet to in excess of
200 feet. The formation originally covered the entire county, but
erosion and solution have entirely removed it in the basins of
lakes lamonia and Miccosukee and in the southeastern corner of
the county (plate 1). Because of the variable top of the Oligocene
sediments upon which the St. Marks Formation was laid down,
and because of the erosional nature of the top of the formation,
the thickness cannot be accurately predicted. St. Marks sediments
are thickest in the northern portion of the eastern half of the
county where, for the most part, they have not been extensively
removed by erosion or solution. In the south half of this eastern
portion, the St. Marks Formation is absent to about 40 feet thick.
Westward from Tallahassee the top of the St. Marks Formation
dips into the Gulf Trough. In the western half of the county, the
entire thickness has been penetrated in core holes WLn-4W-1S-
21-aa and WLn-1S-1W-11-cb where it is 176 and 162 feet thick,
respectively. About one and one-half miles west of Jackson Bluff
in well WLn-1S-5W-24-ad, the top of the St Marks Formation is
at a depth of 248 feet (-162 feet), but the entire thickness was
not penetrated. Not only is the top of the Tampa Age sediments
in this western area low because of the Gulf Trough, but the
thickness increases westward indicating an actively downward
movement of the Gulf Trough during Tampa time.
Thicknesses for the eastern portion of the county are depicted
in the geologic cross-sections on figure 15. Also, a comparison of
figure 17 (structure contour map of the St. Marks Formation) and
figure 16 (structure contour map of the Suwannee Limestone)
reveals a thickness pattern for the Tampa sediments.

Aquifer.-The St. Marks Formation is used throughout the county
as a source of good ground water. Most wells in the eastern half
of the county penetrate through this formation into the Suwannee
Limestone, but the casing is nearly always terminated within this
unit leaving it partially available to yield water.

Outcrops.-The St. Marks Formation is found cropping out all
along the St. Marks River. Two pinnacles of the St. Marks
Formation are exposed (LLn-1N-1W-30-dbb) in the roadcut of






R3W R2W


R IW R I E R 2 E R R3E
G E OR GI A
JP4s^~-T.o __._f /"As


EXPLANATION

iiiiii Areas where the Lower Miocene sediments are missing R
and Oligocene rocks represent the surface cf the
bedrock. ,,00
SLine showing top of the Lower Miocene,in feet,referred o F
to mean sea level. .
Contour interval 20 feet. v ,k












CONTOUR INTERVAL 20 FEET


5o0 1 2 3 A 5ii
..-..... /I I 4 l.5 .


.. .. "|,STA E BOAR OF CONSE RVATIO
2? 1

SLEON COUNTY

C U N TY DIVISION OF GEOLOGY


Mile,

yu


R5W R4W R 3W


R2W


RIW


RI E


R2E R3E


Figure 17. Structure map of Lower Miocene sediments,


R5 W


z





z


0




0
O
0


0



O



r

O

n




z
Uj







0







C/2
z3
bd

cj

I

s:
O
oC

M
C
W?


R 4 W


I





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 65

the truck by-pass on the west side of Tallahassee just north of
U. S. Highway 90, as shown in figure 18.
It is also exposed in numerous sinks in the southern portion
of the county, one of the largest of which is Dismal Sink, located
in the NW/4 of section 17, T 2 S, R 1 W. The following section
was measured at this locality.
Locality LLn-2S-1W-17-da. Section measured on the south face
of the sink.


Bed Description Thickness
(feet)

Pleistocene Series
Wicomico Formation
1 SAND, quartz, fine to medium, loose, very
pale orange to very light gray in color ---- 34

Miocene Series
Alum Bluff Stage-Hawthorn Formation
2 MARL, very pale orange, sandy, very macro-
fossiliferous (mostly oysters and pectens) __ 8-10
3 CLAY, light gray, interbedded with sand,
quartz, fine to medium _--_-- ----- 3

Tampa Stage-St. Marks Formation
4 CALCILUTITE, pale orange, soft but tough,
indurated ledge at top ____- ___----- 8-10
5 CALCILUTITIC CALCARENITE, very pale
orange, macrofossiliferous, moderately soft,
finely silty and sandy _____ -__----- at WL
Base of section
Total thickness exposed ------ __-- 53-57

ALUM BLUFF STAGE
HAWTHORN FORMATION

Historical.-The Hawthorn Formation was named by Dall (1892,
p. 107) for the marine phosphatic limestones in the vicinity of
Hawthorn, Alachua County, Florida. Adequate summaries of this





66 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN


Figure 18. Limestone of the St. Marks Formation overlain by clastics of
Middle Miocene age (locality LLn-1N-1W-30-bb).

formation are found in the Florida Geological Survey Bulletin Nos.
29 and 33 and are not restated here.

Definition and distribution.-Previous workers have placed in the
Hawthorn Formation all of the clastics that occur above the Tampa
Age carbonates in the northern half of the county. In this report,
the Hawthorn Formation is restricted to sediments overlying the
St. Marks Formation and underlying sediments of Choctawhatchee
or younger age.
The Hawthorn was probably deposited over the entire area,
but it is no longer present in the southeastern quarter of the
county due to erosion and solution.

General lithology.-The Hawthorn Formation in Leon County is
composed of fine to medium grained quartz sand, sand-size
phosphorite, silt, kaolinite, montmorillinite and attapulgite, and
sandy, phosphoritic limestone. In the northern half of the county,
the sequence is usually sandy, clayey, phosphoritic silt at the top,
sand and sandy phosphoritic clays in the middle, and sandy





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 67

phosphoritic limestone at the base. The limestone is very pale
.orange, very finely crystalline, moderately sandy, slightly to
moderately phosphoritic, dolomitized and partially recrystallized.
'The Hawthorn and St. Marks limestones are similar, but the
;Hawthorn is more calcitic, with the included quartz sand more
clear and angular, and the St. Marks is not phosphoritic.
SIn the western portion of the area, within the Gulf Trough,
the Hawthorn Formation becomes more calcareous throughout the
section with few distinct beds of clean sand and clay. Also, in
this western sector, the kaolins are usually absent.

Stratigraphic relations.-The Hawthorn Formation unconform-
ably overlies the Tampa Age sediments. This unconformable
relationship is apparent from the distinct lithologic differences
in the eastern half of the county, but the nature of the St. Marks
and Hawthorn is less distinct in the Gulf Trough where plastics
were apparently being deposited very rapidly in a shallow marine
environment. In the Gulf Trough area the writers separated the
Hawthorn and St. Marks Formations on the first occurrence of
a basal conglomerate contact as exemplified in core holes WLn-1S-
4W-21-aa and WLn-1S-4W-11-cb.
In outcrops and in cuttings from water wells the relationship
of the Hawthorn Formation contact with the overlying Miccosukee
Formation is less obvious than that with the underlying sediments.
Sands and clays of the two formations are in contact. However,
their gross appearance is different and distinguishable. Core holes
drilled by the Florida Geological Survey in northern Jefferson and
Leon counties have provided excellent continuous samples across
the Hawthorn-Miccosukee contact. In these cores the lithologies
of the two formations are quite distinguishable and separable.
The Hawthorn Formation unconformably underlies the Chocta-
whatchee sediments in the western portion of the county.

Thickness and structure.-The Hawthorn Formation is variable in
thickness, but in the northern part of the county its maximum
as seen in the core holes shown in section E-E', figure 15, is about
90 feet. Southward, it is 60-70 feet thick in the area just east of
Tallahassee. In the western area the Hawthorn sediments are
'.in excess of 175 feet thick in core hole WLn-1S-4W-21-aa, located
at Jackson Bluff. In well WLb-1S-5W-24-ad, just west of Jackson
Bluff in Liberty County, the Hawthorn is in excess of 200 feet
thick. This thickening within the large Gulf Trough area can be





68 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

observed in other wells in Gadsden and Liberty counties. Cross-,
section D-D', figure 15, depicts this western thickening.

Aquifer.-The Hawthorn Formation is used as a source of water
in the northern part of the county only in a few dug wells. It
serves as an important aquifer in the western portion of the county
along with the St. Marks Formation.

Outcrops.-On the geologic map a large portion of the northern
part of the county is mapped as Hawthorn Formation. In this
area the Miccosukee Formation and the Hawthorn Formation are
very similar in lithology, and weathered surfaces are practically
indistinguishable.
This area of Hawthorn exposure was arrived at by superimpos-
ing the structure contours of the Hawthorn, as determined from
samples from water wells and core holes, on a topographic map
of the area. Where the generalized contours indicated a formation
top at elevations higher than the land surface, the area was mapped
as Hawthorn. On the geologic map (plate 1) this area is described
as where the Hawthorn occurs at or close to the surface.
Good exposures of the Hawthorn occur in several sinks in the
northern section of the county. The best of these is the large sink
at the northern end of Lake Miccosukee, where sands, silts, and
sandy kaolinitic clay are present.
In the Seaboard Air Line Railroad Switchyard B, located in
the southwestern edge of Tallahassee (LLn-1S-1W-3-da), an
exposure of the Hawthorn has yielded excellent vertebrate remains.
Fossil vertebrates representing drum, ray, shark, sawfish, turtle,
snake, alligator, crocodile, bird, horse, camel, a deer-like animal,
rodent, and rhinoceros were recovered here and dated as Miocene
(Olsen, 1964, p. 481-482). The prominent feature at this locality
is the presence of abundant oyster shells, as seen in figure 19.
The following section was described from the north side of
the right-of-way.
Locality LLn-1S-1W-3-da.
Bed Description Thickness
(feet)

Miocene Series
Alum Bluff Stage-Hawthorn Formation
1 CLAY, yellowish gray to pale olive, silty,
waxy --_ -- --- __-- 10-12











GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 69












































































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...........*





































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Fiur 1Mi
xL:n-lS-lW-3-da.
_d ~ B1L~bS




















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.. ........



OK, xT.,,


X Z': M
a g~* ~s~~lh6~ 'w







.... ... ...a
j:
. ~aa 15ro



a pw.
ix, 7x

.. .. 7


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a.-S-W3-a





70 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SE'


2 SAND, quartz, pale orange, fine to medium,
clay as matrix -------__ _---
3 SAND, quartz, light olive gray, medium, ir-
regularly bedded with a waxy, light gray clay
4 CLAY, light gray, waxy ___- --
5 OYSTER BAR, individual oyster shells
(Osterea normalis) lying horizontally (none
found articulated), cemented together by
dissolution and recementation of the calcium
carbonate from the shells. Some vertebrate
remains ------ ---------
6 SAND, quartz, dark yellowish brown, med-
ium, clay as matrix, some vertebrate remains
7 CLAY, dark yellowish orange, with laminae
of moderate yellow brown quartz sand, lime-
stone fragments, some vertebrate remains
8 SAND, quartz, light greenish gray, medium,
containing broken shell fragments and whole
shells of cf. Ostrea normalis. This is the
main vertebrate zone -_____________
9 SAND, quartz, light yellowish gray, medium,
abundant vertebrates from this bed also -----
10 CLAY, gray to brown, waxy,
Base of section
Total thickness exposed -_____________ __


VEN


.05

.58-.67
.25-.33


1.17-1.33

.25-.33


.08-.17



1.00-1.67

.08-.17


13.46-16.72


The Hawthorn Formation is continuously exposed along the
south side of Lake Talquin. The calcareous and clayey nature
of the sediments in this area has permitted a three to six foot
bluff to be cut by the wave action of the water in the lake. About
28 feet of Hawthorn is exposed at Jackson Bluff on the Ochlockonee
River (see description LLn-1S-4W-21-aa, p. 77).
The Hawthorn Formation is exposed in creek beds in the
southeastern section of Tallahassee in Koucky and Myers Parks.
Here it is a light gray, sandy, kaolinitic clay.
The following section was measured in the northeast corner
of an excavation for the Plaza Shopping Center at the northwest
corner of the intersection of U. S. Highway 90 and High Road
on the west side of Tallahassee. The beds exposed in the walls
of the excavation have considerable variation in thickness and
lateral change.





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 71

Locality LLn-1N-1W-27-dd. Elevation at top of section is 165 feet.

Bed Description Thickness
(feet)

Miocene Series
Choctawhatchee Stage-Miccosukee Formation
1 Soil profile-SILT and SAND, moderate red-
dish brown at top grading downward into
mottled red and gray at base of bed; con-
taining iron cemented boulders in base of
bed. Rounded, very coarse sand grains
occur abundantly across transition from
beds 1 to 2 - -_- -- . - --__ 3-4
2 SILT, light gray, sandy, contains boulders as
in bed 1 --- _--------_- ..- 1
3 CLAY, yellowish gray, very silty, has man-
ganese discolorations as blebs and stringers 3-4
4 SILT, mottled, light yellowish orange, red-
dish orange, slightly clayey _------ -- 3

Alum Bluff Stage-Hawthorn Formation
5 CALCILUTITE, pale yellow orange, sandy,
clayey, medium hard, macrofossiliferous
(oysters), phosphoritic --_---- 2
Base of section
Total thickness exposed _----- ---__- 12-14

A core hole was drilled at the above locality to a depth of 89
feet beginning at the base of the measured section and terminated
in Hawthorn sediments.
The following section was measured in the northern part of
the county on the Ochlockonee River.





72 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

Locality LLn-2N-1W-4-dcd, on the left bank of the Ochlockonee
River. Elevation at the base of the section is 90-100 feet.

Bed Description Thickness
(feet)
Miocene Series
Alum Bluff Stage-Hawthorn Formation
1 SAND, quartz, mottled very light green,
light gray and very light brown, very fine-
grained, very silty and clayey (montmoril-
lonite). More clay at top and bottom of bed 17
2 CLAY, montmorillonite and kaolinite, pale
greenish yellow, silty and sandy with sand
occurring as thin laminae and dispersed
throughout the clay, blocky __- _--- 6
3 SAND, quartz, bluish gray, very fine-
grained, silty, slightly clayey (montmoril-
lonite) -___- _-- --- ---_______-_ 4
4 CLAY, kaolinite, white to very light gray,
sandy, with grayish green montmorillonite
blebs _--- -_-----------------_-------- 3
5 CALCILUTITE, very pale orange, slightly
sandy, partially recrystallized, phosphatic
and dolomitic, macrofossiliferous (pecten
impressions and oyster shell fragments) --- 3
Base of section
Total thickness exposed .- ------- 33
Beds 4 and 5 occur 100 feet downstream from beds 1, 2, and 3.

The following section occurs about one-quarter mile down-
stream from Locality LLn-2N-1W-4-dcd.
Locality LLn-2N-1W-4-cd, on the left bank of the Ochlockonee
River. Elevation at the base of the section is 90-100 feet (esti-
mated from topographic quadrangle).

Bed Description Thickness
(feet)
Miocene Series
Alum Bluff Stage-Hawthorn Formation
1 SAND, quartz, mottled gray, bluish gray,
light brown and orange brown fine grained,
loose --------- ---- 10





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 73

2 SAND, quartz, very light purplish to light
olive gray, very coarse, clayey, contains
sandstone nodules cemented with white
clay matrix ___- ----- ------- 5
3 SAND, quartz, light gray with limonitic
staining, medium grained, loose -_______ .50
4 SAND, as in bed two --____-- 1.0
5 CLAY, upper 4 feet is greenish gray, very
silty, sandy, waxy, blocky, grading down-
ward into 5 feet of purplish clay, less silty
than above. The top 4 feet is montmorillonite
and the lower 5 feet is mostly kaolinite with
some montmorillonite and illite ---_ 9
6 CLAY, mostly kaolinite with some mont-
morillonite, white, phosphatic, soft, with
molds of pectens -----_ ___________ 2
Base of section
Total thickness exposed ---- _____ 27.50

The following section was measured about 150 yards from the
U.S. Highway 27 bridge over the Ochlockonee River.
Locality LLn-2N-2W-24-dd, on the left bank of the Ochlockonee
River. Elevation at the base of the section is approximately 80'.

Bed Description Thickness
(feet)
Miocene Series
Alum Bluff Stage-Hawthorn Formation
1 CLAY, kaolinite, very pale orange to light
greenish gray, sandy, calcareous, soft to
moderate soft, with blebs of light green
montmorillonite clay _____________- _- 3-4
2 CALCILUTITE, very pale orange, sandy
and very clayey (montmorillonite and
attapulgite), moderately soft, phosphatic 2
3 CALCILUTITE, pale orange to pale green-
ish yellow, very clayey (montmorillonite
and attapulgite), sandy, macrofossilifer-
ous, interfingers with a green clay ---..---- .79





74 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

4 CALCILUTITE, very pale orange, sandy
and clayey (montmorillonite), moderately
soft to slightly hard -- ---- 3
Base of section
Total thickness exposed --__----- 8.79-9.79

The following section was measured about midway between
U. S. Highways 27 and 90 on the Ochlockonee River.
Locality LLn-1N-2W-1-aa, on the left bank of the Ochlockonee
River. Elevation at the base of the section is 80' (approximately).

Bed Description Thickness
(feet)
Miocene Series
Alum Bluff Stage-Hawthorn Formation
1 SAND, quartz, pale yellowish brown to light
brown, unsorted, very fine to very coarse,
silty, clayey kaolinitee), loose, limonite stain-
ing throughout. Small light purple stringers
occur near the base of the bed (probably
MnO) ,--------- __------------- 8
2 CLAY, mainly montmorillonite with some
attapulgite and illite, pale olive, waxy,
blocky, silty, has one foot clayey silt bed at
base --- ___ -- --_--_________ 2
3 SAND, quartz, pale orange, fine to very
coarse, mostly coarse, clay kaolinitee
matrix) ------ ________---- ___- 1
4 SILT, quartz, mottled light gray to grayish
orange, with laminae of white fine-grained
sand and blebs and small lenses of pale olive
colored clay, like that in bed 2 ---- 2
5 CLAY, mostly kaolinite with montmorillon-
ite, light bluish gray, silty and sandy, waxy,
plastic _____ _-------------- 3
6 CALCILUTITE, white to very pale orange,
chalky, macrofossiliferous (mostly oysters),
silty to very finely sandy, with blebs of light
olive colored clay (montmorillonite) -_ 6
Base of section
Total thickness exposed --.._- ----____ 22





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 75

CHOCTAWHATCHEE STAGE
JACKSON BLUFF FORMATION

Historical.-The term Choctawhatchee was first used by Matson
and Clapp (1909, p. 114) for Upper Miocene sediments in west
Florida that they called marl. The Choctawhatchee unit is
composed of four faunizones, the Yoldia, Arca, Ecphora, and
Cancellaria. The Yoldia and Area are downdip facies of the
Ecphora and Cancellaria. A good historical summary of these
faunizones is given by Puri (1953, p. 27-36) and Puri and Vernon
(1959, p. 131-147). The Ecphora and Cancellaria facies are
present in Leon County, and Puri and Vernon (1964, p. 202) have
applied the name Jackson Bluff Formation to these two faunizones
because they are typically and accessibly exposed at Jackson
Bluff on the Ochlockonee River in Leon County. Because these
facies are lithologically very similar and because separation in
well samples is impractical, they are not divided into separate
units in this report.

Definition and distribution.-The Jackson Bluff Formation
includes all sediments of the Ecphora and Cancellaria biofacies
of Choctawhatchee Age that occur above the Alum Bluff Age-
Hawthorn Formation and beneath the Miccosukee Formation and
younger deposits. It occurs only in the western portion of Leon
County (plate 1). Over 25 core holes were drilled in the
Apalachicola Coastal Lowlands area to delineate the approximate
areal extent of these sediments in the county.

General lithology.-The Jackson Bluff sediments in Leon County
are clayey sands and sandy clays that are very macrofossiliferous.
They are light gray to greenish gray and brown in color. Along
the eastern limits of the formation in the Apalachicola Coastal
Lowlands area there are approximately 12 to 15 inches of dark
gray, non-macrofossiliferous, finely sandy clay on top of the shell
beds.

Stratigraphic relations.-The Jackson Bluff Formation uncon-
formably overlies the Alum Bluff Age-Hawthorn Formation. This
contact is exposed at Jackson Bluff. The Jackson Bluff Formation
unconformably underlies the Miccosukee Formation in well WLn-
1S-3W-6-ad and younger Pleistocene sands in the southwestern
section of the county.





76 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

Thickness and structure.-The thickness ranges from a feather
edge near the eastern limit to in excess of 10 feet at the western
edge of the county. Twenty-six feet of Jackson Bluff were recorded
in a core hole (WLb-1S-6W-13-adc) at Hosford, Liberty County,
about six miles west of Leon County, and 20 feet were assigned
to the Jackson Bluff Formation in well WLb-1S-5W-24-ad, located
2 miles west of Jackson Bluff.
Core holes and outcrop data indicate a southerly dip of about
seven feet per mile for the formation, however, the data used are
too closely spaced to be applied regionally.


Figure 20. Jackson Bluff Formation at locality LLn-1S-4W-21-aa.





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 77

Aquifer.-The Jackson Bluff Formation is not used as an aquifer.
The sediments act as a confining bed to water in the underlying
formation.

Outcrops.-Sediments of the Jackson Bluff Formation are
exposed at Jackson Bluff on the Ochlockonee River (LLn-1S-4W-
21-aa), as shown in figure 20, and at Larkin Bluff (LLn-1S-4W-
30-cad). Several feet are also exposed along Harvey's Creek in
the NE/4 SW/4 of section 9, T 1 S, R 3 W, where the pectens (bed
4, locality LLn-1S-4W-21-aa) are very prominent. The writers were
unable to find this exposure during a traverse of the entire creek
course in 1962, but during a later traverse about 30 yards along
the bed of the creek were found to have up to two feet of good
exposure of the Jackson Bluff Formation at about 80 feet in
elevation. This section is periodically covered by slumping of the
overlying loose terrace sands and by shifting sand bars in the
creek. The formation is also exposed in a creek bank in the
southeast corner of section 7, T 1 S, R 3 W, about 25 yards south
of State Highway 20 beneath a power line. This outcrop is
about 92 feet in elevation.
The following section was measured at Jackson Bluff by the
writers during February, 1964, and at that time the western side
of the pit was being actively excavated.

Locality LLn-1S-4W-21-aa, on the left bank of the Ochlockonee
River. Elevation at the base of the section is approximately 35 feet
(see geologic well log WLn-1S-4W-21-aa).


Bed Description Thickness
(feet)
Recent-Pleistocene Series
1 SAND, quartz, light gray, silty, loose with
no bedding apparent ----______ 6-8
2 SAND, quartz, yellow orange, silty and
clayey, more indurated than bed 1; some thin
bedding apparent; mottled in part 0-6

Miocene Series
Choctawhatchee Stage-Jackson Bluff Formation
Cancellaria facies (occurs only in eastern and
southern portion of abandoned borrow pit)





78 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN


3 SHELL MARL, very pale orange to light
gray, very sandy, very macrofossiliferous.
Specimens of Cancellaria common _______--


3.50-5.00


Ecphora faces (occurs in western portion of borrow pit)


4 SHELL MARL, grayish orange to bluish
gray, sandy, very macrofossiliferous. Pecten
very prominent --_-----------_-----
5 SHELL MARL, light brown, sandy, macro-
fossiliferous; becoming bluish gray at base
(1 foot) -_-_ ___ -

Alum Bluff Stage-Hawthorn Formation
6 CLAY, light gray, blocky; thinly laminated
in the upper part with veinlets of calcite
toward the top. Weathers to brownish gray
7 CLAY, gray, yellow and orange mottled, very
sandy, cross-bedded. Contains lenses of purer
clay with poorly preserved mollusks ____-
8 MARL, yellow orange, very sandy. Contains
poorly preserved casts and molds of mollusks,
with Turritella and Cardium identified.
Indurated near top forming a nodular ledge
9 SAND, quartz, greenish gray, medium to
coarse grained, cross-bedded -----
10 CLAY, dark-blue-green; in places ferrugin-
ous and orange-brown in color. Contains
white, course sand and tends to disappear
to the south ______----------------
11 SAND, quartz, light gray, medium to coarse,
slightly clayey, very similar to bed 9 ----_____
12 MARL, very pale orange, very sandy; occa-
sional casts and molds of mollusks. Forms
a bench at the bottom of the bluff ----
Base of section
Total thickness exposed -----------


5.50-8.00


3.50





3.50


10



4

1-2



1.00-1.50

1.50


5

44.50-58.00


MICCOSUKEE FORMATION

Historical-The Miccosukee Formation is composed of a hetero-
geneous series of plastics that have been referred to as the Lafay-





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 79

ette Formation (Pliocene), the Alum Bluff Formation (Oligocene to
Lower Miocene), the Hawthorn Formation (Middle Miocene), the
"Unnamed Coarse Clastics" and the "Miocene Red-beds" (Middle-
Upper Miocene), and the Citronelle Formation (Plio-Pleistocene).
Much of the coastal plain of the southeastern states has surficial
plastics, reddish orange in color, that for the most part are devoid
of fossils and immediately overlie deposits as old as the Oligocene.
The similarity of these widespread plastics and their occurrence
upon sediments occupying such a wide range in the geologic section
has lent itself to the confusion associated with their origin and
age.
Recent work on the regional geology of Florida (Puri and
Vernon, 1959) pointed up the need for a detailed survey of the
surficial sediments in north Florida that would determine the
source of the deposits, the nature of their deposition, and their
geologic age.
In 1909, Matson and Clapp (p. 141-145), in a report on the
geology of Florida, noted the occurrence of surficial plastics in,
".. .a belt about 40 miles in width, extending from near the
Suwannee River westward to Escambia County . ." with "...
large tracts . found in Gadsden, Leon, and Jefferson Coun-
ties . ." They assigned these plastics to the Lafayette Formation,
then thought to be Pliocene, and considered them to be fluvial or
estuarine. They recognized the precariousness of assigning all
the red plastics within this area to the Lafayette Formation
because of the absence of fossils, and the sections they listed as
representative of the formation included sediments presently
assigned to the Miccosukee Formation and the underlying
Hawthorn Formation.
Sellards (1912, p. 19), in a report on the soils of Florida, said,
". there is found in Florida an extensive deposit of sand, gravel
and lenses of clay. This material forms the surface covering over
a large extent of northern and central Florida as well as parts
of the adjoining states. .. The classification of this superficial
material has given rise to much difficulty owing chiefly to the
fact that in Florida it is practically non-fossiliferous. .. It has
been regarded in recent years by most writers as Pliocene in age,
although. . there is no satisfactory evidence that it may not be
early Pleistocene. . This locality (type locality of the 'Lafayette
Formation at Oxford, Lafayette County, Mississippi) has recently
been re-examined by Berry who, upon the evidence of the fossil
plants finds the deposits to be Eocene age. From this evidence it





80 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

would appear that the Florida material can not be correlated with
the Lafayette as defined from the type locality, since in Florida
the material everywhere rests upon deposits later than Eocene."
Even though Sellards (1912, p. 22-27) negated the assignment
of these deposits to the Lafayette Formation, he described the
weathering and erosional processes that probably resulted in the
character of these sediments, and stated (p. 27) that "The amount
of erosion and disintegration to which the formation has been.
subjected is such as to give weight to the view that the material
accumulated during either Pliocene or early Pleistocene."
In reporting on a vertebrate find in northern Leon County,
Sellards (1916, p. 82) stated, "After passing through the surface
materials which consist of coarse red, clayey sands, 15 to 20 feet.
in thickness, the well from which these fossils were obtained enters
the gray phosphatic sands and clays characteristic of the Alum
Bluff formation. . Sellards failed to give an age assignment
to the upper 15 to 20 feet of plastics but he did imply that they
were younger than the lower Miocene-Alum Bluff Formation.
In a subsequent report, Sellards (1917, p. 104) stated, "Formerly
the red sandy clays at' the surface of this area were supposed
to be separable from the Alum Bluff and to belong to the Lafayette
formation. It does not seem, however, that there is any definite,
or well defined break within this deposit. . The red sands lying
near the surface in this area represent in fact a zone of partial
decay. If there is a persistent dividing line, such as could be used
in defining a formation. . it has not been detected, and the whole
deposits may for the present be referred to the Alum Bluff
formation."
Mossom (1926, p. 184) described that, ". the red sand-clay
hills of north Florida are the [in situ] weathered Chipola
formation [Middle Miocene]." This is the basal formation of the
Alum Bluff Group (Gardner, 1926, p. 1).
In 1929, Cooke and Mossom (p. 115-116) stated that the
Middle Miocene-Alum Bluff Group of west Florida is equivalent
with the Hawthorn Formation of northern peninsular Florida, and
assigned the subsurface sandy limestone (p. 123) of Leon County
to the Hawthorn Formation. They also included in the Hawthorn
unit the plastics lying upon the sandy limestone as they were
considered to be residuum of the Hawthorn Formation.
MacNeil (1949, p. 98-101), in a discussion of the Pleistocene
shorelines in Florida and Georgia (in part the Tallahassee Hills
area) said, "The high terrace is the dissected surface lying





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 81

entirely above an altitude of 150 feet. . The identification of
Marine terraces in this paper is based on the coexistence of shore-
line scarps, which are presumably wave-cut cliffs. . Without the
evidence of a scarp, however, and until study of the soils and
sediments yields some definite evidence, there seems to be little
way of determining what part, if any, of the terraced surface
above 150 feet is marine and what part is fluvial."
Vernon (1951, p. 184) considered the entire plastic section at
Tallahassee to represent the Hawthorn Formation. He stated,
"The sediments composing the Hawthorn formation at Tallahassee,
Florida, and eastward are fine-grained silts and sands interbedded
,with phosphatic-clayey sands, some of which are so thinly bedded
as to appear laminated and some are cross-bedded." This
description encompassed characteristic deposits of both the
Hawthorn and the Miccosukee Formations. Vernon (p. 184)
*further stated, "In distribution and lithology these beds resemble
deltaic sediments and a large delta plain is believed to have been
present over much of the area..
Yon (1951) made a study of the surficial sediments from
Chattahoochee to Ellaville, an inclusive area extending 40 miles
|to the west of Leon County and 35 miles to the east of Jefferson
County, and he concurred with the opinion that the sediments
were deltaic in origin and Hawthorn in age.
Doering (1960) assigned much of the higher plastics throughout
the coastal plain of the southeast to the pre-glacial Pleistocene-
Citronelle Formation, and this assignment included the higher
clastics in the Tallahassee Hills area of north Florida. Pirkle et
al. (1963, 1965) have reported on similar sediments in peninsular
Florida that they assigned to the Citronelle Formation. Their
published conclusions have been based only on sedimentation
studies and morphology since they reported no datable fossils to
Support an age assignment.
The writers have examined the cuttings from approximately
200 water wells and 15 core holes in Jefferson and Leon counties.
In addition every available road cut and ditch excavation has been
examined in detail. The surface deposits in the Tallahassee Hills
.area of Jefferson and Leon counties represent an upper plastic
unit that is deltaic in origin, as pointed out by previous investi-
.gators, and unconformably overlies a lower marine plastic unit.
The deltaic unit caps the hills and high-level flats, whereas the
marine plastics occupy the lower inter-hill areas, though these
'lower areas are in part rolling topography as well. The gross
*





82 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

lithologies of each unit are distinctly different; however, thi
difference is frequently not readily apparent in single exposure
In western Leon County the two elastic units are separated by
tongue of very fossiliferous Choctawhatchee age sediments. Th
writers believe the upper unit can be mapped across Leon Count
Florida, and in the adjacent counties. This unit was formally
named the Miccosukee Formation by Hendry and Yon (1967).

Definition and Distribution:-The Miccosukee Formation include
all plastic sediments in the Tallahassee Hills area of North Florid
that occur above the Hawthorn Formation of Alum Bluff Age (plhi
1). In western Leon County, it includes all plastic deposits young
than the Jackson Bluff Formation of Choctawhatchee age an
older than the Pleistocene sediments. They are the deposits of
delta that encroached upon Middle and Upper Miocene sediment
throughout North Florida. They are absent in the portion of th
county that lies south of the Cody Scarp.
The Miccosukee Formation is typically exposed around Lak
Miccosukee in Jefferson County and the town of Miccosukee
northeastern Leon County. The section exposed at locality LJf-3N
5E-31-aa is designated the type section. Other sections tha
typically present the Miccosukee sediments are described under
"Outcrop" as localities LTh-3N-3E-2-cc, LLn-1N-1E-21-ab, LLn-lS-
1W-6-a, and LLn-1N-1W-29-ba. A core hole (WLn-2N-3E-8-aa)
drilled by the Florida Geological Survey one half-mile west of
Miccosukee is an excellent record of approximately the entire
Miccosukee section. These cores are on file at the office of the
Florida Geological Survey in Tallahassee, and a detailed description,
is included in the section on well logs (see p. 147).
G. S. Visher's (1965, p. 46-54) article describing environmental
reconstruction from verticle profiles very adequately describes
the sequences of deposits that characterize the Miccosukee
sediments.

General Lithology:-The Miccosukee Formation is composed of
heterogeneous series of clastics commonly referred to as the
"Miocene Red Beds" and "Unnamed Coarse Clastics." The deposits
include continental sediments of inter-bedded and cross-bedded
clays, silts, and sands and gravels of varying coarseness and ad,
mixtures thereof. Most of the strata show abrupt lateral changes
in thickness, stratification, texture, and composition even though.
the deposits are widespread. The color is predominantly grayish-
orange to grayish-red, and frequently is mottled. There is usually;





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 83


Figure 21. Laminae and thin beds of clay within the Miccosukee Formation
(locality LLn-3N-1E-17-aa).


rery little soil zone or mantle, but deep lateritic weathering is
common The finer-grain fraction of the formation weakly
ements the sediments.
A striking feature in the sediments is the laminated to thin-
edded sequence of light colored clay and reddish orange quartz
ilt and sand, shown in figure 21. These thinly bedded deposits
probably represent the latest stage of deposition of the deltaic
cycle.
The clays are present as thin beds, laminae, and matrix, and
nineralogically are montmorillinite, kaolinite and illite. The
nontmorillinite is usually gray to grayish green in color, whereas,
he kaolinite and illite are usually white to very light cream. The
lilt, sand and gravel fraction is composed of quartz, and is
predominantly silt to sand size.
Sandstone lenses and float are frequently present in the
formation. These sandstone deposits are usually formed through
the cementation of the coarser fraction by clay that has been
reached from the matrix of the overlying clayey sands by
percolating ground water. The writers found that the zone of





84 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

cementation generally occurs immediately above a reasonably
impermeable clay or silt. Differential compaction of the bed.
commonly disrupts these sandstone lenses into a zone of sandstone
float. This float is typically exposed at localties LLn-3N-3E-20-bq
and LLn-1N-1E-21-ab, shown in figure 22.
Ironstone pebbles are common where a thin weathered mantle
is formed. These pebbles are essentially iron cemented sand that
are up to an inch or more in diameter and usually hard and'
highly polished. Their color ranges from reddish brown to almost
black.

Stratigraphic relations:-In Leon County the Miccosukee Formas
tion unconformably overlies the Hawthorn Formation in th(
northern section, and the Jackson Bluff Formation in the wester
portion. It is absent in the southern section. Though the nature
of this contact with the Hawthorn Formation is difficult t
determine since both formations are essentially plastics, there
enough mineralogic difference in their gross aspect to differentiate
between them. This contact is readily discernible in the core
taken by the Florida Geological Survey from selected localities
across the Tallahassee Hills area of north Florida (cross-sectiol
E-E', fig. 15). The stratigraphic position and age of the uppe
plastics is not well documented as yet; however, the writers note
that these upper red plastics were separated from the lower elastic
by the intervening Choctawhatchee Age-Jackson Bluff Formatio
in samples from core holes at Hosford (WLb-1S-6W-13-dc), Libert
County and at Harvey's Creek (WLn-1S-3W-6-ad), Leon Count
Where the Jackson Bluff Formation underlies the Miccosuk
Formation the contact is distinctly unconformable since there
a distinct change in both the lithology and the fauna.
Yon collected fossil teeth from these upper plastic sedime
(Miccosukee Formation) during the investigation of Jeffers
County, and Olsen (1963, p. 312) described and correlated th
with Upper Miocene fauna found elsewhere in the United Stat
From this evidence these deltaic sediments are assigned at lea
in part to the Upper Miocene. Whether these sediments shou
be restricted to a Miocene age or whether they represent Plioce
as well is not yet known; however, their lithologic character
distinctly different from Pleistocene sediments and is, therefo
considered to be pre-Pleistocene in age.

Thickness and Structure:-The original thickness of th
Miccosukee Formation appears to have been between 80 and 10






GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 85


"R,-- M: .. .... .
IFF






M, 01 o











Figure 22. Localities LLn-3N-3E-20-bd-above and LLn-lN-1E-21-ab-below,
depicting the occurrence of sandstone float in the Miccosukee Formation.





86 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

feet as seen in cores (cross-sections, fig. 15) from the series of
core holes drilled on top of the highest hills in northern Leon
and Jefferson counties. However, streams have greatly dissected
the formation leaving thicknesses ranging from 0-90 feet. In
western Leon County, the Miccosukee is only 10-20 feet thick.
The source of the sediments comprising the Miccosukee
sequence was from the north, but because of the nature of the
surface upon which these sediments were laid down, the dip cannot
be accurately computed. The cross-sections on figure 15 illustrate
an east-west strike (E-E') and north to south dip (A-A', B-B', and
C-C').
Intraformational structures are abundant cross-bedding, joints,
faults, cut and fill features, and lenticularity of beds. The bedding
is usually horizontal, but is commonly disturbed, shown in figure
23. The wavy bedding, joints, small faults, and abnormal dips
indicate the formation has undergone extensive slumping which
has been caused both by post-depositional compaction and by
adjustment of the unconsolidated plastics and by solution of the
underlying carbonates. Pirkle and Yoho (1961, p. 247-266) report
solution of the bedrock as the cause of folding and jointing in
plastics of similar origin and age in north peninsula Florida. The
small faults formed by this compaction are infrequently exposed
in roadcuts, and the best one (fig. 23) observed during the









4'k









Figure 23. Disorientation of thin beds in the Miccosukee Formation by
faulting, locality LTh-3N-3E-2-cc.





GEOLOGY AND GROUND WATER RESOURCES OF LEON COUNTY 87

investigation was north of the town of Miccosukee at localilty
LTh-3N-3E-2-cc in Georgia.

Aquifer:-There are a very few dug wells that terminate in the
Miccosukee Formation, but for the most part, the Miccosukee
Formation is not used as an aquifer because of its poor
permeability.

Outcrops:-The Miccosukee Formation mantles much of the
northern half of Leon County, and a geologic section could be
obtained in almost every roadcut and ditch excavation. The
nature of the formation is such that no two sections could be
correlated. The following measured sections illustrate the varied
depositional sequences that are present.
Section LJf-3N-5E-31-aa shows the general aspects of the
formation and has been designated as the type section (fig. 3).
Locality LJf-3N-5E-31-aa: Roadcut on the east side of U. S.
Highway 19, about 3.1 miles south of the Georgia-Florida State
line, Jefferson County, Florida.

Bed Description Variable
thickness (feet)
Miocene Series
Choctawhatchee Stage-Miccosukee Formation
1 SAND, mottled yellow brown, red brown, and
greenish gray, very fine to medium, some
coarse, angular to subangular, clayey, cemented
firmly with clay and iron oxide, contains thin
laminae of white clay that apparently dip north-
ward under bed 2, these crossbedded laminae
are most noticeable near the contact of bed 1
with 2; top of bed 1 becomes a deeply weathered
red color (rust) and is included in the
weathered zone.
Near the contact of bed 1 and 2 the sand at
the base of bed 1 becomes fine to coarse and
angular to subrounded, predominately coarse
grained; there is no sharp contact between
bed 1 and 2 except that they weather different-
ly, also near the contact of the units the color
in bed 1 becomes a mottled purple red and





88 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-SEVEN

greenish gray, with large gray spots up to 6
inches in diameter. Northward along the road-
cut bed 1 occurs again. However, here the color
is more a light yellow brown, with some mottled
red and greenish gray color; this part of the
unit contains crossbedded laminae that appar-
ently dip southward under bed 2. The sand is
coarse grained in this part of the unit near the
contact of bed 1 and 3 (clay bed), and has mas-
sive 2-inch joints filled with greenish gray clay.
These joints have good relief because limonite
cemented sands border their outside edges and
hold them up. The sediments on the extreme
northern end of this roadcut are believed to
belong to bed 1, but are a deeply weathered
red color and all bedding characteristics are
destroyed ----._. . .._____ .__...____. ...__ ___up to 13.0
2 SAND, quartz, mottled purplish red, red
brown, yellow brown, and greenish gray, very
fine to medium, some coarse, angular to sub-
angular, more clayey than bed 1, firmly cement-
ed by clay and iron oxide, massive; no sharp
contact with bed 1. On weathered surface the
color is much lighter than fresh cut. Joints
filled with greenish gray clay up to 14.C
3 CLAY, yellow brown and greenish gray,
slightly sandy, silty, massive, weathers blocky,
sharp contact with bed 1 that lies above up to 5.5
Base of section

Locality LTh-3N-3E-2-cc. This section typically illustrates the
overall characteristics of the unit. It is 1.25 miles north of the
Florida-Georgia State line, and though the Township-Range
system of land classification is not used in Georgia, the Florida
system was projected to include this outcrop. The section was
measured on the west side of Georgia State Highway 122
(extension of Florida State Highway 59).