FLRD GEOLOSk ( IC SUfRiW


COPYRIGHT NOTICE
[year of publication as printed] Florida Geological Survey [source text]


The Florida Geological Survey holds all rights to the source text of
this electronic resource on behalf of the State of Florida. The
Florida Geological Survey shall be considered the copyright holder
for the text of this publication.

Under the Statutes of the State of Florida (FS 257.05; 257.105, and
377.075), the Florida Geologic Survey (Tallahassee, FL), publisher of
the Florida Geologic Survey, as a division of state government,
makes its documents public (i.e., published) and extends to the
state's official agencies and libraries, including the University of
Florida's Smathers Libraries, rights of reproduction.

The Florida Geological Survey has made its publications available to
the University of Florida, on behalf of the State University System of
Florida, for the purpose of digitization and Internet distribution.

The Florida Geological Survey reserves all rights to its publications.
All uses, excluding those made under "fair use" provisions of U.S.
copyright legislation (U.S. Code, Title 17, Section 107), are
restricted. Contact the Florida Geological Survey for additional
information and permissions.










FLORIDA STATE BOARD

OF


CONSERVATION


FARRIS BRYANT
Governor


TOM ADAMS
Secretary of State



J. EDWIN LARSON
Treasurer



THOMAS D. BAILEY
Superintendent of Public Instruction


RICHARD ERVIN
Attorney General



RAY E. GREEN
Comptroller



DOYLE CONNER
Commissioner of Agriculture


W. RANDOLPH HODGES
Director


AGRI.
CULTURAJ
LIBRARY







LETTER OF TRANSMITTAL


7lorida Geological Survej

Tallahassee
February 18, 1963
Honorable Farris Bryant, Chairnwan
Florida State Board of Conservation
Tallahassee, Florida
Dear Governor Bryant:
The report, "Geology and Ground-Water Resources of Flagler, Put-
nam, and St. Johns Counties, Florida," was prepared by B. J. Bermes,
G. W. Leve, and G. R. Tarver of the U.S. Geological Survey as a part
of its corporation with the Division of Geology. It is being published as
Report of Investigations No. 32.
The report was proposed by the Director of the Division of Geology
as an opportunity to include in one project the water resources of the
area, should they exist as surface or ground waters, and to study the
ground-water resources through a sequence extending from a recharge
area to a discharge area. The relationships of surface water to non-
artesian ground water and to artesian ground water, the paths of move-
ment of ground water, the effects of chemical, physical and biological
additives to all water have been considered. This is one of the first
studies of water resources that was undertaken as a resource study
rather than as an attempt to solve an existing problem of water-resource
development.
We are grateful to the members of the Legislature that made the
study possible through providing funds, and to the citizens of each
county whose cooperation in the study made the results meaningful.
Respectfully yours,
Robert O. Vernon, Director
and State Geologist




















































Completed manuscript received
October 31, 1962
Published for the Florida Geological Survey
ByJ-Rose Printing Company
Tallahassee, Florida
February 18, 1963

iv








CONTENTS
Page
Abstract ........................................ ... ......... .. 1
Introduction .......................................................... 3
Previous investigations ............................................ 4
Well-numbering system ............ ................................. 5
Acknowledgments ................................................ 5
SGeography ........................... ................... ........ 5
Location and area ......................... ................... 5
Climate ........................................................... 7
Population and industry ......................................... 7
Physiography ..................................................... 8
Drainage .................................................... 11
Geology ..... ..................... ............. ................ 11
Method of investigation ................. ......................... 11
Formations .................................................. 14
Lake City Limestone ................. ........................ 14
Avon Park Limestone ........................................ 17
Ocala Group .............................................. 27
Inglis Formation ......................................... 27
Williston Formation ...................................... 28
Crystal River Formation ................................. 29
Hawthorn Formation ......................................... 30
Upper Miocene or Pliocene deposits ............................ 31
Pleistocene and Recent deposits ................................ 32
Structure ....................................... ............. 33
Geologic history ................................................. 35
Ground water ...................................................... 40
Nonartesian aquifer ....................................... 41
Deposits of high average permeability ...................... .43
Deposits of low average permeability ....................... 45
Artesian reservoir ......... .. .... ............. 48
Occurrence of aquicludes and aquifers .......................... 48
Secondary artesian aquifers ................................ 48
Floridan aquifer ....... ...... ......... .......... ... 50
Fluctuations of water levels ............................ 51
Fluctuations caused by rainfall ......................... 51
Fluctuations caused by pumping ........................ 54
Fluctuations caused by earthquakes ..................... 55
Fluctuations caused by ocean tides ..................... 56
Fluctuations caused by changes in atmospheric pressure ... 57
Piezometric surface .................................. 58
Area of artesian flow ............................... 63

V







vi CONTENTS

Water-bearing characteristics ......................... 64,
Reservoir operation ................................... 70
Wells ........................................... 7:
Quality of water ................................................... 7I
Nonartesian and secondary artesian aquifers .......................... 741
Floridan aquifer .................................................. 71
Salt-water contamination ......................................... 85
Nonartesian and secondary artesian aquifers ...................... 80(
Floridan aquifer .......................................... 87
Summary and conclusions ............................................. 90
References .......................................................... 95







ILLUSTRATIONS
Figure Page
1. Well-numbering system ........................................ 6
2. Peninsula of Florida showing the location of Flaglcr, Putnam, and
St. Johns counties .......................................... 7
3. Flagler, Putnam, and St. Johns counties showing the Pleistocene
marine terraces .............................. ....... In pocket
4. Graphs showing the data collected during and after the construction
of test well 937-122-1 ........................ ................. 15
5. Graphs showing the data collected during and after the construction
of test well 939-134-11 ........................................ 16
6. Generalized geologic cross sections showing the formations penetrated by
wells in Flagler, Putnam, and St. Johns counties ............ In pocket
7. Diagram comparing the velocities of water from different depths in the
limestones of Eocene age in well 943-144-1 ...................... 26
8. Flagler, Putnam, and St. Johns counties showing the altitude of the top
of the limestone of Eocene age and the first limestone of Eocene age
penetrated by wells .................................... In pocket
9. Flagler, Putnam, and St. Johns counties showing the altitude of the top
of the Inglis Formation ...................................... 34
10. Diagram showing the generalized hydrologic conditions in northeastern
Florida .................................. .... ...... 42
11. Cross section showing distribution of permeability in the post-Eocene
deposits of Flagler and St. Johns counties ....................... 44
12. Flagler, Putnam, and St. Johns counties showing the altitude of the base
of material of high average permeability and the approximate outcrop
area of material of low average permeability ...................... 45
13. Cross section showing distribution of permeability, lithology, and elec-
trical and water-bearing characteristics of the deposits between Hast-
ings and St. Augustine ....................................... 46
14. Graphs showing the rainfall at St. Augustine and water levels in well
952-120-2, secondary artesian aquifer; well 954-129-1, secondary arte-
sian aquifer; and well 955-125-1, Floridan aquifer ................. 49
15. Graphs showing the relation between the water level in well 926-131-1
in Crescent City and the rainfall in Crescent City ................. 52
16. Graph showing the relation between the water level in well 939-138-1 in
Palatka and the rainfall in Palatka ............................ 53
17. Hydrographs showing the seasonal fluctuations and the progressive trends
of the artesian heads in wells 939-138-1, and 925-138-1, in Putnam
C county ............................................. 54
S18. Hydrographs of well 947-126-1 in St. Johns County ................. 55
19. Hydrographs showing the effect of ground-water pumpage, earthquakes,
and ocean tides on the water levels ....... ...................... 56
20. Effect of atmospheric pressure on the water levels in well 949-123-1, 6
miles southeast of St. Augustine ................................ 58
21. Peninsula of Florida, showing the piezometric surface of the Floridan
aquifer ....................................................... 59
22. Flagler, Putnam, and St. Johns counties showing the piezometric surface
in April 1956 ............................................ 60
23. Flagler, Putnam, and St. Johns counties showing the piezometric surface
in September 1956 ............................ ... .......... 61






viii ILLUSTRATIONS

24. Flagler, Putnam, and St. Johns counties showing the piezometric surface
in September 1958 ........................................... .
25. Flagler, Putnam, and St. Johns counties, showing the area of artesian
flow in April 1956 and in September 1958 .................. In pocket
26. Geometric analysis of the piezometric surface near Spuds to determine
the coefficient of leakance ..................................... 65
27. Geometric analysis of the piezometric surface near Cody's Corner to
determine the coefficient of leakance ............................. 66
28. Graphs showing linear relationships between quantities listed in table 5.. 68
29. Graphs showing the barometric efficiency of the Floridan aquifer ...... 70
30. Graphs showing the relationship between the rainfall at Crescent City
and the water level in well 927-115-1 at Bunnell .................. 72
:31. Flagler, Putnam, and St. Johns counties, showing the carbonate hardness
of water from wells that penetrate the Floridan aquifer ...... In pocket
:32. Diagram showing the chloride content of water versus depth of well in
an area 3 miles north of Cody's Corner, Flagler County ............ 84
:3. Flagler, Putnam, and St. Johns counties showing the chloride content of
artesian water, in parts per million, from wells that penetrate less than
200 feet of the Floridan aquifer ....................... .. In pocket
:34. Flagler, Putnam, and St. Johns counties, showing the chloride content of
artesian water, in parts per million, from wells that penetrate more than
200 feet of the Floridan aquifer .......................... In pocket
:35. Graph showing the relation between the chloride content of water and
the water levels in artesian wells ............................... 89
:36. Flagler County showing the location of wells ................ In pocket
:7. Putnam County showing the location of wells ................ In pocket
:3S. St. Johns County showing the location of wells ............... In pocket


Table
1. Population of Flagler, Putnam, and St. Johns counties in 1950 and 1957 8
2. Stratigraphic units of Flagler, Putnam, and St. Johns counties ........... 12
3. Geologic data from wells in the area ............................... 18
-4. Pleistocene terraces in Flagler, Putnam, and St. Johns counties ......... 38
5. Summary of pertinent data and results of pumping tests ............... 67
6. Analyses of water from the aquifers overlying the Floridan aquifer in
Flagler, Putnam, and St. Johns counties .......................... 7(i
7. Analyses of water from the Floridan aquifer in Flagler, Putnam, and St.
Johns counties ................................................ 78






GEOLOGY AND GROUND-WATER RESOURCES OF
FLAGLER, PUTNAM, AND ST. JOHNS COUNTIES, FLORIDA

By
B. J. Bermes, G. W. Lcve, and G. R. Tarver

ABSTRACT

Flagler, Putnam, and St. Johns counties in northeastern Florida
:omprise an area of 1,895 square miles. The climate is humid subtropical
imd the area has an average annual rainfall of about 50 inches.
The topography of the counties is influenced by a series of marine ter-
-aces, seven of which have been recognized and mapped on the basis of
heir altitude above present sea level. The terraces are the Coharie (170-
115 feet), Sunderland (100-170 feet), Wicomico (70-100 feet), Penholoway
(42-70 feet), Talbot (25-42 feet), Pamlico (10-25 feet), and Silver Bluff
(0-10 feet).
Underlying Flagler, Putnam, and St. Johns counties are several
thousand feet of limestones of Eocene age which form the major artesian
aquifer in the area. The limestone formations are the Lake City Lime-
stone, Avon Park Limestone, Inglis Formation, Williston Formation, and
Crystal River Formation. Overlying the limestone are sediments of
M\iocene or Pliocene age. These sediments are overlain by Pleistocene
and Recent deposits which blanket the area to a depth of 20 to 140 feet.
Ground water in the area occurs under both nonartesian and artesian
conditions. The nonartesian aquifer extends from land surface to a depth
of at least 150 feet below land surface. It includes deposits of Miocene
or Pliocene age and of Pleistocene and Recent age. The nonartesian
aquifer yields moderate to large quantities of water in central and eastern
Flagler and St. Johns counties and generally yields small quantities of
water to domestic wells throughout the remainder of the area. The non-
artesian aquifer is recharged locally by direct infiltration of raiinfall and
by upward leakage from the underlying aquifers.
Secondary artesian aquifers are an important source of water in parts
of eastern Flagler and St. Johns counties where water from other aquifers
is highly mineralized or difficult to obtain. The secondary artesian
aquifers are composed of lenses of sand, shell, and limestone. The
aquifers range in depth from less than 10 feet to more than 300 feet below
sea level, and in thickness from less than 1 foot to about 15 feet. These
aquifers occur most often in the area east of the St. Johns River and in
the north-central part of Putnam County. The secondary artesian aquifers






FLORIDA GEOLOGICAL SURVEY


are recharged from the overlying nonartesian aquifer and from the under.
lying Floridan aquifer.
The Floridan aquifer is the major source of ground water in Flagler,
Putnam, and St. Johns counties. It consists of limestone formations of
Eocene age and permeable beds in the lower part of the Hawthorn
Formation of Miocene age which are hydrologically connected to the
limestones. The Floridan aquifer is recharged in western and south-
eastern Putnam County, in the area north of Elkton in central St. Johns
County, and probably in parts of Flagler County. In each of these areas
the water table is higher than the piezometric surface and water probably
enters the aquifer through sinkholes or where the confining beds are thin.
Artesian pressure in the Floridan aquifer declined about 4 feet during
the period 1953-56. A seasonal decline of about 20 feet occurred during
the spring of 1956 in the farming areas because of deficient rainfall and
an increased withdrawal of artesian water, principally by irrigation wells.
Artesian pressure rose from September 1956 to September 1958 as a result
of above-normal rainfall and a decrease in the withdrawal of water from
the Floridan aquifer.
The altitude of the piezometric surface of the Floridan aquifer in
Flagler, Putnam, and St. Johns counties ranges from about 100 feet in
western Putnam County to less than 5 feet near the confluence of the
St. Johns and Oklawaha rivers. Generally, water in the aquifer in these
three counties flows from the recharge area in the north-central part of
the State, including northwestern Putnam County, toward the south and
east. Wells tapping the Floridan aquifer in the three counties will flow
in many areas; however, the area of flow has decreased in the past few
ears.
Pumping tests in the area indicate that the Floridan aquifer has a
coefficient of transmissibility ranging from 173,000 to 360,000 gpd/ft (gal-
lons per day per foot), a coefficient of storage ranging from 1.57 x 10-'
to 9.4 x 10'-, and a coefficient of leakance from 1.5 x 10-3 to 1.75 x 10-"
gpd/ft3 (gallons per day per cubic foot). The largest coefficient of leak-
ance was in central and southern Flagler County where the principal
confining bed is either thin or absent. Pumping tests, current-meter data.
and geologic information indicate that the primary water-producing zone
of the Floridan aquifer in Flagler, Putnam, and St. Johns counties is the
top 50-200 feet of the aquifer.
The chloride content of water from wells developed in the Floridan
aquifer ranges from less than 10 ppm (parts per million) in western
Putnam and northeastern St. Johns counties to several thousand parts pei
million along the coast in Flagler and St. Johns counties. Water in the






REPORT OF INVESTIGATIONS No. 82


itpper 200 feet of the Floridan aquifer generally contains less chloride
Lhan the water below 200 feet. When the artesian pressure is lowered by
excessive pumping in farming areas the chloride content of the water
more than triples in some wells.
In some areas saline water has contaminated the existing fresh-water
supplies in both the nonartesian and the Floridan aquifer. The nonarte-
sian aquifer has been contaminated by upward movement of saline water
from the Floridan aquifer and by intrusion of saline water from nearby
salt-water bodies. In localized areas the nonartesian aquifer is contami-
nated by water entrapped during inundatiorn'of the land by the sea in
Pleistocene time.
In the Floridan aquifer excessive discharge for a long period of time
from the Haw Creek Basin, Oklawaha-St. Johns River valley, and near
the coast in Flagler and St. Johns counties has lowered the artesian
pressure in the upper part of the aquifer and saline water has migrated
upward into the aquifer. In the farming areas near Hastings, East
Palatka, and in parts of Flagler County upward coning of saline water
in the Floridan aquifer occurs during periods of maximum pumping. The
upward coning of saline water from the deeper parts of the aquifer can
be partially controlled by proper well spacing and pumping practices.
Generally in the Floridan aquifer water samples show a progressive in-
crease in chloride content with depth.

INTRODUCTION
A large part of the economy of Flagler, Putnam, and St. Johns coun-
ties is based on winter vegetable farming. The most important winter
vegetable farming area is in the St. Johns River valley, where adequate
supplies of water for irrigation are available from artesian wells.
In recent years there has been a decline in the artesian pressure in
the Floridan aquifer in the farming areas and this decline has resulted
in a decrease in the area of artesian flow. In some areas it has become
necessary to install pumps in wells that had previously produced an ade-
quate supply of water by natural flow. In addition to the loss of artesian
pressure, there has been a noticeable increase in the salt content of the
water. Wells that had previously produced fresh water became salty
and in some cases had to be abandoned.
Recognizing the threat to the fresh-water supplies of the area, the
State Legislature appropriated funds for an investigation of the ground-
water resources of the area. This investigation began in November 1955
as a part of the statewide cooperative program between the U.S. Geo-
logical Survey and the Florida Geological Survey.






FLORIDA GEOLOGICAL SURVEY


The purpose of the investigation was to make a detailed study of
the geology and ground-water resources of the area with special em-
phasis on the problems of declining water levels and salt-water contami-
nation. This report contains the interpretive results of the investigation.
The ground-water records of the investigation have been published by
the Florida Geological Survey as Information Circular 37.
The investigation was made under the immediate supervision of M. I.
Rorabaugh, district engineer.
PREVIOUS INVESTIGATIONS
A study of the geology and ground-water conditions in the vicinity
of the St. Augustine well field was made by A. G. Unklesbay (1945). This
report included a geologic cross section of the well field and a table of
chemical analyses of water from the city wells. Other than this report,
no detailed investigations of the geology and ground-water resources of
the three-county area have been made prior to the present study. How-
ever, several general reports on investigations have included information
on the area. These reports have been published by either the U.S. Geo-
logical Survey or the Florida Geological Survey and are listed below.
Cooke (1945, p. 42, 48, 225, 236, 268, 272, 285, 291, 295, 296, 304, 310;
pi. 1) describes formations exposed at the surface in the three-county
area. A report by Vernon (1951, fig. 11, 13, 33; pl. 2) has generalized
subsurface structural maps and a geologic cross section that includes
the three-county area.
The geology and ground-water conditions in the project area are
discussed in a report by Stringfield (1936) on the artesian water in the
Florida Peninsula. This report includes maps of the Florida Peninsula
showing the area of artesian flow, areas in which the artesian water con-
tains more than 100 ppm of chloride, and the first published map of the
piezometric surface of the Floridan aquifer. It also contains water-level
measurements and other data on some of the wells in the three-county
area. A report by Stringfield and Cooper (1951) contains a geologic cross
section and a brief discussion of the artesian water in the three-county
area.
Chemical analyses of water from the wells in the three-county area
are included in reports by Collins and Howard (1928, p. 214, 226-227)
and Black and Brown (1951, p. 53, 96-98).
Reports by Matson and Sanford (1913) and Sellards and Gunter (1913)
briefly mention the occurrence and quality of ground water in the three-
county area. These reports include descriptions and logs of several wells
in the area also.






REPORT OF INVESTIGATIONS No. 82


Interim reports on each county were prepared by the U.S. Geological
survey and published by the Florida Geological Survey as follows: Infor-
nation Circular 13 entitled, "Interim report on the ground-water re-
;ources of Flagler County, Florida," by Boris J. Bermes; Information
Circula- 14 entitled, "Interim report on the ground-water resources of
St. Johns County, Florida," by George R. Tarver; and Information Cir-
cular 15 entitled, "Interim report on the ground-water resources of
Putnam County, Florida," by Gilbert W. Leve.
WELL-NUMBERING SYSTEM
The latitude and longitude well-numbering and location system is
shown in figure/. This system consists of a statewide grid of 1-minute
parallels of latitude and 1-minute meridians of longitude, thus covering
the State with 1-minute quadrangles. The number assigned to each well
consists of three sets of digits separated by hyphens. The first set of
digits is derived from the last number of the degree and the two numbers
of the minutes of latitude, that bound the quadrangle on the south; the
second set of digits is derived from the last number of the degree and
the two numbers of the minutes of longitude, that bound the quadrangle
on the east; the third digit or digits is the number assigned consecutively
to each well located in that particular quadrangle as it was inventoried.
Wells inventoried in this area prior to this study were numbered con-
secutively within each county; all such wells located and subsequently
used in this study have been renumbered to conform to the new system.
With this system wells referred to by number in the text can be located
on figures 36, 37, and 38.
ACKNOWLEDGMENTS
Appreciation is expressed to the well drillers who furnished infor-
mation and assisted in the collection of rock cuttings and water samples.
These include: A. C. Gray, Sr., of the Gray Well and Pump Co., Louis
Broer, Sam Jordan, N. Harrell, J. Glenn, Clarence Prevatt, and Ernest
Wilson. ,Special thanks are due the many well owners for their coop-
o ration in contributing information and otherwise aiding the investigation.
Members of the Florida Geological Survey rendered assistance during the
field investigation. Mr. E. C. Pirkle and Mr. H. K. Brooks of the Univer-
sity of Florida gave information and advice on the geology of the area.

GEOGRAPHY
LOCATION AND AREA
Flagler, Putnam, and St. Johns counties comprise an area of 1,895
quaree miles, nominally 1,212,600 acres adjacent to the Atlantic Ocean






6 FLORIDA GEOLOGICAL SURVEY






REPORT OF INVESTIGATIONS No. 32


a the northeastern part of F ida.ts location with respect to adjoining
countiess is shown in inj/
CLIMATE
The climate of the area is humid subtropical. According to the records
)f the U.S. Weather Bureau, the mean annual temperature is about 70F

*DegrL s d longi de w t Of the Greenwc, England. prme mell an
of as- It ri r. e I I


S' 28.26' I 1 28926
89 832 S31. 86130 2



:figure. peninsula of Florida showing the location of Flagler, Putnam, and St. Jon


near the coast and about 72F inland. The average annual rainfall is
about 50 inches, of which between 50 to 75 percent falls between June
I and October 30.
~- POPULATION AND INDUSTRY

The population of the three counties in 1950 and 1957, and the
percent change between these years are shown in table 1. The 1950
population figures are based on records of the U.S. Census Bureau and






FLORIDA GEOLOGICAL SURVEY


the 1957 population figures were estimated by the Bureau of Economic
and Business Research, University of Florida.
TABLE 1. Population of Flagler, Putnam, and St. Johns Counties in
1950 and 1957
Percent change
County April 1, 1950 July 1957 1950-1957
Flagler 5,800 5,300 -8.6
Putnam 23,600 33,000 39.8
St. Johns 25,000 33,700 84.8

Agriculture is one of the principal industries of Flagler, Putnam, and
St. Johns counties, and potatoes and cabbages are the principal crops.
According to the 1958 annual statistical summary of Florida's vegetable
crops prepared by the U.S. Department of Agriculture and the University
of Florida Agricultural Experiment Station, the three counties produced
about 182,000 tons of potatoes at an estimated value of $8,000,000 and
about 43,000 tons of cabbage at an estimated value of $2,500,00.
Another important industry is the production of wood pulp and paper.
A large processing plant, the Hudson Pulp and Paper Co., is located
about 3T miles west of Palatka and its expansion has been a major reason
for the population increase in Putnam County.

PHYSIOGRAPHY
The topography of Flagler, Putnam, and St. Johns counties is pre-
dominantly a series of marine terraces. They were formed at times in the
past when the sea stood at different levels, submerging greater or lesser
portions of land according to its height. When the sea was relatively
stationary for long periods, the sea floor was eroded by waves and cur-
rents to a fairly level surface. When the sea dropped to a lower level,
the sea floor emerged as a level plain or terrace. The landward edge of
each terrace became an abandoned shoreline, which was generally
marked by a low scarp. Cook (1945, p. 248) recognized seven and
possibly eight marine terraces in Florida, each formed at different alti-
tudes above present sea level. Seven of these terraces, the Coharie, Sun-
derland, Wicomico, Penholoway, Talbot, Pamlico, and Silver Bluff are
recognized in the three-county area.
The general configurations of these terraces in the area were deter-
mined from topographic maps and aerial photographs, and are shown on
figure 3. Erosion has modified or destroyed the old shorelines and the level
plains in many places; therefore, the terraces were mapped primarily
by their altitudes above present sea level.






REPORT OF INVESTIGATIONS NO. 32


The Coharie terrace is the highest and oldest terrace present in the
.rea. The Coharie shoreline was not found but scattered remnants of the
terrace remain in western and north-central Putnam County at elevations
between about 170 and 215 feet above present sea level. The most
extensive occurrence of the Coharie terrace is on a high sandy ridge,
called "Trail Ridge," that extends northward from about 2 miles north-
northeast of Interlachen through central Putnam County. A number of
sandhills on this terrace have altitudes of over 220 feet, and they were
probably above the surface of the Coharie sea.
The landward boundary of the Sunderland terrace stands approxi-
mately 170 feet above sea level and its outer margin is bounded by the
shoreline of the next younger terrace at an altitude of 100 feet. The
Sunderland terrace has been considerably modified by erosion. Remnants
of the terrace remain in western and north-central Putnam County and
in southeastern Putnam County, in the vicinity of Walaka and south of
the Oklawaha River.
The shoreline of the Wicomico terrace at an altitude of 100 feet is
locally well preserved and it is usually marked by a steep slope at its
inner boundary. Its outer limit is generally poorly marked by the shore-
line of the next younger terrace, the Penholoway at an altitude of 70 feet.
The Wicomico terrace is present in western and northcentral Putnam
County but remnants are also found as far east as San Mateo and near
the western side of Crescent Lake in eastern Putnam County. The ter-
race is best developed in a 1-to-5-mile wide band along the eastern side
of Trail Ridge. Here it is bordered by a steep rise to the Sunderland
terrace on the west and a steep downward slope to the lower and
younger terraces on the east.
The configuration of- the Penholoway terrace has been severely modi-
fied by the numerous streams that drain from the higher and older ter-
races. Its inland margin coincides with the shoreline of the Penholoway
sea at an altitude of 70 feet but it is poorly developed and difficult to
trace in the field. Its outer margin is bounded by the fairly well devel-
oped shoreline of the next younger terrace at an altitude of 42 feet. The
Penholoway terrace roughly parallels the eastern edge of Wicomico
Terrace through western and central Putnam County. Remnants of the
terrace are found in eastern Putnam County, particularly in the vicinity
of Palatka, San Mateo, south of the Oklawaha River, and a strip about
1 to 9 miles wide between the St. Johns River and Crescent Lake.
The Talbot terrace is well defined in eastern and southern Putnam
countyy and in a 3-to-11-mile wide band that extends through central
.t. Johns and central Flagler counties. It is noticeably absent along







FLORIDA GEOLOGICAL SURVEY


the St. Johns River and Crescent Lake. The inland boundary of the
terrace is about 42 feet above sea level and it is usually marked by a
wave steepened slope that rises to the next higher terrace. The outer
boundary of the terrace is the shoreline of the next lower and younger
terrace at an altitude of 25 feet. The outer edge of the Talbot terrace
is particularly well defined throughout eastern St. Johns and northeastern
Flagler counties where it is an almost straight line that is about 2 to 4
miles inland and parallel to the present coastline.
The Pamlico terrace is a gradual slope with the inland margin at
approximately 25 feet above sea level and the outer margin at an altitude
of approximately 5 to 10 feet, which is the shoreline of the next lower
terrace. The Pamlico terrace extends through eastern St. Johns and east-
ern Flagler counties in a narrow band that parallels the present coastline.
It is also present in a wide band along the St. Johns River and Crescent
Lake in eastern Putnam and western St. Johns and western Flagler
counties.
The area that has an altitude between 10 feet above sea level and
sea level has been mapped as the Silver Bluff terrace (fig. 3). The terrace
is present along the present coastline of St. Johns and Flagler counties,
and along the St. Johns and Oklawaha rivers, and Crescent Lake. The
areas mapped as Silver Bluff terrace along the rivers and lakes probably
are not true marine terraces but are instead river terraces that were
formed when the streams were 5 to 10 feet higher than their present
altitude.
The Silver Bluff, Pamlico, and Talbot terraces form a relatively flat
plain that slopes toward the Atlantic Ocean in eastern St. Johns and
eastern Flagler counties, and toward the St. Johns River and Crescent
Lake in central and western St. Johns and western Flagler counties and
in eastern Putnam County. The plain is interrupted in eastern St. Johns
and eastern Flagler counties by a series of narrow sandy ridges and low
intervening swampy areas which are elongated parallel to the coastline.
The elevation of the plain averages less than 30 feet above sea level, but
some of the sandy ridges are 40 feet or more above sea level.
The Penholoway, Wicomico, Sunderland, and Coharie terraces form
an upland of rolling hills in western Putnam County and a wide band
of hills between Crescent Lake and the St. Johns River in eastern Putnam
County. The surface features of the uplands consist of a few relatively
level areas, numerous ridges and low sandhills, and sinkholes. The sink-
holes were probably formed by the removal and collapse of underlying
soluble limestone. In most cases, the sinkholes have been partly filled
with water to form lakes. These sinkhole lakes are easily recognized by







REPORT OF INVESTIGATIONS No. 32


their circular shape and their lack of a surface-water outlet. They are
\most prominent on the Sunderland terrace in western Putnam County.
The land surface of the uplands ranges in altitude from about 42 feet
-where it merges with the lowlands to more than 220 feet, but most of the
Suplands are between 70 and 170 feet above sea level.

DRAINAGE
Eastern St. Johns and eastern Flagler counties are drained by the
channel of the Intracoastal Waterway. Central and western St. Johns
and central and western Flagler counties and most of Putnam County
are drained by the St. Johns River and its tributaries. The higher ter-
races, especially in western Putnam County and between the St. Johns
SRiver and Crescent Lake, are partly drained through lakes and sinkholes
Into the limestone aquifer. The hilly uplands are well drained but the
streams on the flat lowlands are so poorly developed that much of the
area is marshland.

GEOLOGY1

The geologic formations exposed at the surface in Flagler, Putnam,
Sand St. Johns counties are undifferentiated deposits of Pleistocene and
Recent age which are underlain by deposits of late Miocene or Pliocene
age. The latter deposits are usually underlain by the Hawthorn Forma-
tion of early and middle Miocene age; which is underlain by limestone
formations of Eocene age. Where the Hawthorn Formation is absent,
the limestone formations of Eocene age directly underlie the upper Mio-
cene or Pliocene deposits.
The geologic formations generally penetrated by water wells in the
area and their approximate thickness, general lithologic character, and
water-bearing properties are listed in table 2.

METHOD OF INVESTIGATION
Most of the information on the geology and ground-water resources
of the area was obtained from existing wells or from wells that were
constructed while the investigation was in progress. Geologic information
was obtained by collecting and examining rock cuttings from a number
of water wells drilled by private owners and from test wells drilled by

I The classification and nomenclature of the rock units in this report conform
to the usage of the Florida Geological Survey and also, except for the Ocala Group,
with those of the U.S. Geological Survey which regards the Ocala Group as two
formations, the Ocala Limestone and the Inglis Limestone.













Itecent and
Pleistocene


Pllocene(?)


Miocene


Eocene


lrlratigralic. unit
W tellrn Iteorlinderr
Putnllamn o. of area

Pleistirenic
and Iterrnt
depxlits


Post-llawthorn
to
Recent
deposits


Late Miocelne
or Pliocene
deposits


Hawthorn Formation


Crystal River
Formation
W 1'illiston
Formation

nglis Formation
Inglis Form.ation


Avon Park Limestone


Lake City Limestone


1See disclaimer on page 11.


A|pro4iiiiate thiknilr. itrfro)








to

I N)
20- o I)0




I-. 12(0


0-120


0-50


5s(-) 110


150-245


225+


S'ln ii'ii r1 M 1ai11
u rin it uar t
sand, rcix iiiiia,
and shell gand
Poorly sorted clay lenses
fine to very
e"arse sand,
kaolin, and
4andy clays Fine to nedi-
u'n and, shell
and green ( al
rareous silty
clay


Gray to bluish-green, plastic
phosphatie, sand clay; and
thin beds of sand and sandy
limestone


White to cream, chalky, mas-
sive fosiliferous, marine, lime-
stone
Tan to buff, granular, marine
limestone
Tan to butf, coarsely granular
to mealy, marine limestone;
contains thin beds of dolomite
and zones of foraniniferal co-
quina


White to reddish-brown, hard,
dense limestone and dolomite;
contains restricted zones of
soft, porous, and locally chalky
limestone; formation more
co-pletely dolomitized west of
St. Johns River


Alternating beds of brown to
buff, porous limestone; brown
to white, maive limestone;
bluish-gray to tan, dense, crys-
talline dolomite


Watrr-lt'ariig priop ertirs


Ninartesian aquifer sones of relatively hidh average permeability, generally
supplies srnall to nmierute ainounts of water to rural do-netic wells and munic-
ipal wells tapping roqliinia or rnediu 'i to coarse sand beds; yields vary locally
idependinl ulron texture and extent of deposits.


Nonartesian and secondary artesian aquifers; zones of relatively low average
per 'eahility, locally yield small anoounta of nonartesian water to wells tap ing
medium to fine grained sands in the Pleistocene and Recent depoits, Late
Miocene or Pliocene dep sits and in the Hawthorn For ration; locally yield
moderate amounts of artesian water to wells tappin shell bed in the late Mio-
cene or Pliocene deposits and sand and li-nestone lenses in the Hawthorn For-
mation,


Impermeable clays and marls in both the Late Mincene or Pliocene deposits 0
and in the Hawthorn Formation con'nes the artesian water in the Eocene M
Li nestones and in the thin, lenticular sand, shell, and li nestone beds above 0
the Eocene Limestone.



Floridan aquifer; yields large quantities of water to wells; utilized as the primary
source of ground water in the project area. The formations that comprise the
Ocala (roup are similar in lithology and hydrologic properties and are con-
sidered to be a single hydrologic unit.


Yields large amounts of water from soft, porous zones but dense, indurated
zones restrict permeability so that generally yields are not as large as from over-
lying Ocala Group.


,' ^-


'I'Am.i., 2. Strallgral)hh, Uilils (J Flagli-I., and St. johlis CoIllith's


--- ~


1


- '--~-~--~-' ~I~----~-----I I


I~--~---I--








REPORT OF INVESTIGATIONS No. 32


the Geological Survey. In addition, geologic information was obtained
from drillers' logs, rock cuttings on file with the Florida Geological
Survey, and electric logs. An electric log is a graph of the electrical
characteristics (generally the resistivity and spontaneous potential) of
the rocks penetrated by a well plotted against depth. Most of the electric
logs were made by a Widco single-electrode logger. In wells where the
conductivity of the water was relatively high as compared to the re-
sistivity of the limestone a different method was used to make an electric
log. The electric log was made by passing a low-frequency, constant-
intensity current between two small electrodes spread 18 inches apart
along the axis of the bore hole and observing on a voltmeter the changes
with depth of the electric potential at a third small electrode spread 4
feet below the midpoint of the other two electrodes. The apparatus was
calibrated by assuming the resistivity of the clay in the area as 1 ohm-
meter, and the apparent resistivity of the clay bed occurring at a depth
of 160 feet in well 949-123-3 as equal to the true resistivity (fig. 12). The
current intensity was then adjusted until the indicated potential was 1
millivolt. Therefore, because the indicated potential in the casing was
essentially zero, the proportionality factor relating potential to resistivity
for this electrode configuration (Heiland, 1940, p. 828) becomes 1,000
meters/ampere and the voltmeter was calibrated to read resistivity ac-
cordingly. Because the assumptions made are only approximately true,
these resistivity logs were not used for quantitative determination of
fluid content. However, because the three-electrode configuration elimi-
nated much of the effect of the bore hole, this type of resistivity log is
more useful than the single-point resistivity log in correlating thick zones
of resistant rocks and defining soft limestone formations in areas where
the ground water is moderately mineralized.
In areas where geologic and ground-water information could not be
obtained from existing wells, test wells were drilled to determine the
nature of the water-bearing characteristics of the deposits above the
Eocene limestone. In addition 40 holes, were augered to a depth of 10
to 93 feet in Flagler, Putnam,"and St. Johns counties; and ..contrac-
tors using cable-tool drilling machines .drilled eleven 2-inch diameter
test wells from 66 to 168 feet deep in Flagler and St. Johns counties
and one 6-inch diameter test well 54 feet deep in northwestern Putnam
County. Supplemental hydrologic and geologic information on the lime-
stone formations of Eocene age was obtained by contract drilling of two
6-inch diameter test wells; one in eastern Putnam County was drilled
to a depth of 547 feet and one on the Flagler-St. Johns counties bound-
ary was drilled to a depth of 621 feet. During the drilling of the 2- and
6-inch diameter wells the following information was collected:







FLORIDA GEOLOGICAL SURVEY


1. Rock cuttings at approximately 5-foot intervals.
2. Length of time required to drill through each foot of rock.
3. Water samples at regular depth intervals (from the bailer) for chloride
analysis.
4. Water samples from isolated sections of the well for complete chemical
analysis of the water.
5. Water-level measurements at different well depths to determine both the
composite pressure in the entire open hole and the pressure in isolated sec-
tions of the well.

Upon completion of the two 6-inch diameter deep test wells, electric
logs were made of each well to determine the characteristics of the
Eocene limestone. In addition, a current-meter traverse was made in
the 6-inch diameter test well in eastern Putnam County to locate the
water-producing zones and to determine the rate of internal flow in the
well. A summary of the pertinent data collected during and after the
construction of test wells 937-122-1 and 939-134-11 is shown diagram-
matically in figures 4 and 5.
All rock cuttings collected in the field during this investigation or
obtained from the files of the Florida Geological Survey were examined
under a binocular microscope to determine their texture, mineral com-
position, and fauna. Stratigraphic position and age were determined
both by faunal assemblage and lithology.
Table 3 lists wells in the area with geologic information. The table
includes the approximate land-surface elevation of wells, the depth below
land-surface datum of the formations, the depth below mean sea level
of the top of the limestone formations of Eocene age, and the source
of information for each well.

FORMATIONS
The following discussion of the formations does not include rocks
older than the Lake City Limestone of middle Eocene age. The older
and deeper rocks are not generally tapped by water wells in the area
of investigation because sufficient water can be obtained from the over-
lying formations and the water from the deeper rocks is more highly
mineralized. The geologic cross sections in figure 6 show the geologic
formations generally penetrated by wells in the area.

LAKE CITY LIMESTONE
The Lake City Limestone was applied by Applin and Applin (1944)
to limestone of early middle Eocene age which underlies all of penin-
sular Florida. According to Cooke (1945, p. 46) it is 400 to 500 feet






SELF LITH- RELATIVE DRILLING TIME CHLORIDE CONTENT
AGE POTJNTIAL OLOGY RESISTIVITY (min/per foot (parts per million)
10 hms 5 10 15 20 100 200 300 400 500

5o0





0 1 50
G50
V0 FORMATIONI --- --.


.200


0
I-








r 450 o-






0 uj
o0o -


E Sand

Cloy
? Shell

SPhosphate


EXPLANATION
hal" r Land surface
SCal Well casing
SLimestone

SDolomite Open hole .
Limestone and/
or Dolomite


Figure 4. Graphs showing the data collected during and after the construction of test well 937-122-1.



































Figure 5. Graphs showing the data collected during and after the construction of test well 939-134-11.







REPORT OF INVESTIGATIONS No. 32


thick in the northern part of Florida and from 200 to 250 feet thick in
the southern part of the peninsula.
In Flagler, Putnam, and St. Johns counties only a few water wells
are known to have penetrated the Lake City Limestone. Well 945-142-1
penetrated 230 feet of the Lake City Limestone without reaching older
formations.
The Lake City Limestone consists of alternating beds of brown to
buff, soft, porous, fossiliferous limestone; brown to white, hard, dense,
massive limestone; and bluish gray to tan, dense indurated, crystal-
line dolomite. The dense, indurated limestone and dolomite beds were
readily detected from the soft, porous limestone beds during the drill-
ing and testing of test wells 937-122-1 and 939-134-11. The dense, in-
durated beds greatly retarded the drilling rate and registered a relatively
high resistivity when tested with an electric logger. This is shown
graphically in figures 4 and 5. Both test wells 937-122-1 (fig. 4) and
939-134-11 (fig. 5) show distinctive, soft zones separated by numerous
dense indurated zones within the formation.
The soft, porous limestone beds contain abundant microfossils, par-
ticularly Foraminifera. The most diagnostic fossil of the Lake City Lime-
stone is Dictyoconus americanus which was selected by Applin and
Applin (1944) as a guide fossil for the formation. The following fossil
species were identified in well cuttings from this formation in the area:
Dictyoconus americanus (Cushman)
Discorbis inornatus Cole
Fabiana cubensis Cushman and Bermudez
Fabularia vaughani Cole and Ponton
The Lake City Limestone supplies water to a few deep wells in the
area. However, information collected during the drilling and testing of
the deep test wells indicates that the dense, indurated limestone and
dolomite beds are relatively impermable and that most of the water
in the formation is obtained from the soft, porous limestone beds. These
softer beds are separated by the more indurated limestone and dol-
omite beds. Whenever the indurated beds are continuous for a con-
siderable distance they greatly restrict the upward or downward move-
ment of the water and in some cases they may possibly isolate some
water-producing zones from the rest of the aquifer.

i) AVON PARK LIMESTONE
The Avon Park Limestone was named by Applin and Applin (1944)
for a limestone of late middle Eocene age penetrated by wells in Polk











TAaLE 3, Geologic Da ta from Wells in the Arem
Source of Data: C, rock cuttings; DI, driller's log; El, electric log; Et, estimated; Rpt, reported.


Approl Depth, in feet below land surface of geologic formations
Appro. -
U. 8, mate
Geological elevation Late
survey of land Pleistocene Miocene or Hawthorn Crystal Williston Inalis Avon Park Lake City
well number surface and Recent Pliocene Formation River Formation For.nation Limestone Limestone
(feet) deposits deposits Formation


FLAOLER COUNTY


Elevatlo
in feet
below m
of top o
Eocene
Limestone


I, Florida
Geological
mI Source Survey
f of data well
number
ie


018-118-1 ........

918-118-2........

919-119-3.........

919-120-1.......

919-123-2..........

920-112-1.......

921-116-1.........

921-117-3.........

921-118-4.........

922-110-1.........

922-120-1.........

923-111-1.........

923-118-5........

924-118-1.........

924-122-6.........

926-117-1.........

925-123-1.........


18

17

18.5

18.5

15

30

25

15

10

25

12

15

14



15

7

15


0-24



0-24


24-62



24-82


0-24 24-70

0-50 50-90

............ .. .........

0-37 37-78

0-86 ............

0-72



0-30 30-85

0-27 27-93



0-39 39-65

0-60 60-120

0-65 ...... ...

- No samples--


126-146



164-188

150-180

............

............

............

............





............





............

...., ...o


82-110



00-07







.....03-....
....... ....






............

03-05



. ..... .....


105-125 ............


62-126



110-164

70-150

07-107



78-88

88-106





85-130





65-66

............


125-168


-44

-48

-01

-51

-82

-57

-53

-71



-75

-73

-81

-53

-50


.... ........,



. ,.,I .... .

... .. .....

......... ...



............i

. ........





............,

96-103



............
....... I.....


0

El

C

C, A






C

DI

Rpt

C

C

El

C

C, DI

DI

C


W-4067



W-4065

W-4067






W-4066





W-1528







W-197

W-196

W-3781


...........

. ...........,

............





.....I.......

..........I..
............






............



..... .....
..,o ~ ..
., oo o

,,,,,,,,'' '


...........



............

..o ...




. ..



...........

............


..... I ......








926-106-1......... 10
926-108-1......... 5

927-114-1.......... 20

927-115-9......... 18

928-108-5......... 10

928-111-2......... 20
928-116-......... 20

928-122-13........ 23

929-124-8......... 25

93-180-1......... 7

933-110-1......... 5

933-116-1......... 40
033-120-1......... 43

936-11-4.......... 12

940-112-1........... 12


..... I ....... o ... ... ... .- I .........
0-30 30-107 107-114 ............

0-52 52-96 06-101 ............
0.50 50-65 ............ ............
- 0-56 ............ ............

0-20 29-09 00-113 ............


No samples ............
do.- ............

0-102 102-131 131-168 ............
0-22 22-77 77-140 ............

0-13 13-83 83-136 ............

0-70 70-116 116-151 ...........


........... I ........... ............ .........


. .. ......... 190-2 0 .... ............
. .......... ....... .. ............


... ..... ,... .. ........ I ............,






............ 190-280 280-410 ............

140-150 150-240 240-400 ............

.... .., .... I .. ,. ... ,... ..... .......
-- 140-152-- ........................

. ...151-164. .... .. ..
151-164 ............ ............ .............


. .......... ...I......... ............


-124

-99 Eat

-85 Eat

..,,........


-95 Est

-85

-167

-115
-165 Eat

-135


-108
-142
-151


FLAGLER-ST. JOHNS COUNTIES

7-122-1............. 38.78 0-70 70-95 95-145 ............ 145-180 180-287 287-442 442-622 -106 C, I..........

PUTNAM COUNTY

923-135-1 ......... s ............ .... ............ ... ..... ....... ...... -73 El ........

925-135-1......... 26 ................... .... ........ .......................................... -87 El

926-131-2......... 55 -- Nosample- 00-115 ............ ............ 115-130 ............ ............ -60 C W-4058
926-132-1......... .. 65 0-50 50-88 ............ .................. 88-115 ............ ... ........ -23 C W-4069

028-140-4.......... 30 0-15 15-30 30-60 ............ 60-80 80-87 ............ ............ -30 C


Rpt

C
C

C, DI
DI

C

Rpt
C

C
C

C

C
C

El

DI


w-3651


W-195

















W.i-480
Wgi-480













TAnE US.-( Continued)


U. S
Zoological
Survey
well number


Approxi-
mate
elevation
of land
surface
(feet)


020-184-1...'...,. 50
929-138-1,,,... 00
20-140-1........ 20
931-142-1, ...... 20
031-142-2.......'. 20
932-180-2......... 07
032-141-2 ......... 10
934-159-1....... 85
935-146-1......... 30
935-153-1......... 85
036-135-2......... 46
937-142-1'......... 60
037-152-1......... 05
037-153-1......... 115
937-153-2......... 110
037-154-1......... 135
937-159-1......... 00
937-201-1......... 180


Depth, in feet below land surface of geologic formation


Late
Pleistouene Miocene or
and Recent Pliocene
deposits deposit


Hawthorn
l'or;:atinl


0-105 105-118 118-12.1
-- No amples-- 00-135
do. ----- 34-50


0-40 40-70 70-135
0-80 80-08 05-138
0-18 18-22 22-62
-- 0-00- 00-110
I. ".. ..... ..... ...
,-0-71-- ...........
0-35 35-00 00-155
No eample----
Norecord -
- 0-120- 120-105
0-38---. ............
- 0-120---- 120-205

..8..... '80.. ..... ...... 7 3
0-78-- 78-03


Crystal Williston
River Formatiuo
Formation


Inglli Avon Park
Formation Limestone


........ .. ,. 1 124-145
..... .... 135-150 150-178
........... -80 ....


............ 13-155 185-220
............ 3-145 145-235
............ --- 02-06..-----
110-281 -




.......... 155 ............


185-348 ----------
105-201

...........-- No ee........... 38630.........
------No sniples---- 388-307
, .. .. I ... .. ... ... .. .. .......
............ ......... ... I...... I... I. I


..........,

345




307-533


Lake City
Limestone


Elevation,
in feet
below mel
of top of
Eocene
Limestone


-74
-75
-38
-112
-115
-38
-52
-25
-140


-109
-184
-00
-80
..........
-70
-43


Florida
Geological
Survey
well
number


W-4063
W-4082
W-4050
W-1B38
W-1838A
W-2633







W-1400


W-84
W-217


Source
of data


C
C
0
DI
C, DI
El
C
DI
El
C, DI
0, DI
C
DI
C, DI
C
C
El


C, DI


,,,,,, .., ,.. .,. ,.

,. ,, ,. .. ,.
... n ....... ~ .. . .


B


-" 1- -"'-7 --- --~---------~--------


- -- --


- ----







938-136-2 ...,....

938-136-3.......
938-138-4. .......
038-142-2 ...,,,..
939-124-8 ........
039-134-9.......
939-134-11.....
930-201-1.........

940-135-7........
* 940-140-1........

940-188-1.........
041-135-2 ........
041-137-83........

041-202-2 ........
042-132-1 ........
942-141-1 .........
942-200-1.....,...

943-138-1...., ,.
943-144-1 .........
043-148-1.........
943-155-2..,,,.....
943-200-1 ...,,..,,..

944-150-1 .........
948-142-1 .........
948-134-1..,......


15
10

35
70

10
10
19
157
18
10
185

18
10
115
12

7
00.0
70
15
128
100
115
115
20
12


0-20 20-75
0-40 43-120
0-20 20-04
0-80 80-103




0-25 25-60
0-08----

----0-01-----

. .......... ... .........
0-93--


0-33 -100
----- 0-33


0-00 00-80


0-84 84-102
0-70 70-110
0-74 74-02
- 0-38 ----

No sample I 02-115
--0-07----

0-84 84-110
0-52 52-119


75-161
140-180
04-173

103-249




00-115
08-73

01,130






100-171
33-37


80-100


102-217
110-205
02-231


115-127
07-120
110-180
110-220


250-270
215-250







180-230


...........


250-340







230-200


- 161-100 190-238

.... 180-212 212-247
... 173-105 ............
243-250 ........... ...




115-130 130-170 176-280
I,. ..... ... .. .. ,. .... .. .... ,
130-140 143-185 185-245

. .. ... ..


....... ,, .. .. .. ... ..
...... 171-200 200-227


........ ... .. .100-3 .00
, ,. . ,I ... . I .. .
............ 100-300 1


. ...... .. .









280-502














300-305


.. .,.. ..,
. .. . ... .
.. ... .....


502-547



. .., .... .. .
.........,..,
, ,


340-575







0-...... .
200-470
... I. ...


-140
-104

-138
-179
.-110

-110
-06


-112

-165


-120
-101


-168

-183
-32
-147

-100
-103


-12
-5

-100
-217


c
C, DI

0
0
El

El
C, DI, El

0


DI

C, DI
El


C, DI
El
C, DI
DI
El

C, Di1
0
C

C, DI
0

C

C, D1
C


............,
... ........
575-740






.....70-700
.. ..... ...
470-700
............


I


W-610











W-4001
W-973









W-3035
W-388


W-3036




W-4004


W-3903


217-250
205-215
231-206


127-138
120-131


220-238











TApLx 3,- (Continued)

Depth, in feet below land surface of geologic formations
Approl-- Elevation, Florida
1, 8, mats in feet Geological
Geological elevation Late below mol Source Survey
suvey of land Pleistocene Miocene or Hiawthnrn Crystal Willitaon Inglis Avon Park Lake City of top of of data well
wll number surface and Recent Pliocene Formation River Formation Formation Limestone Limestone Eocene number
(feet) deposits deposits Formation Limestone

9-137- I............ ............ ............. ... .... .-1 .1-1 ...... ... ..... -228 El ......

ST. JOHNS COUNTY

39-128-I......... 17 ....................... ............. ................... -148 El
940-129-7......... 17.40 0-28 28-75 75-118 -- 118-320- .-.........., -102 C, DI W-152
940-130-1......... 19 No amples--- 2-110 No samples 270-412 ........... -01 C ..........
942-127-1........... 23 0-63 63-84 84-168 165-178 175-208 205-310 ........................ -142 C ......
943-327-1......... 26 .. .. ...... .............. .. ..... ............................ .......E...........
043-128-7......... 20 0-40 40-85 85-184 184-201 201-230 230-330 330-414 ............ -164 C .......
945-118-3........ 28 0-38 38-01 1-175 ............ ......... ......... ................ ........... C, DI ...
94-115-1......... 7 ................ ............. ....... -13 DI
946-127-1 ......... 30 ............ ... .............................................. -132 El.
947-125-4... .... 20 .............. ...... .... ...... ................. -148 El
947-126-10........ 20 0-70 70-187 187-240 240-285 285-320 ........................ -158 C, DI .....
948-133-1........ 7 ....... ................ .................. .......... -190 D
940-123-1......... 25 .................... ................ .... ...... .................. El............ -198 E .........
940-12-3 ......... 42 ............ ........ .... ................ ..... ........ ............ -168 DI
949-133-2 ......... 6 ............ ................ ................ ............ ............ ............ -186 D







9-10-119-.........

0510- 130........

; 951-127-1........

982-118-1.........

952-120-. ........

52-128-1.........

958-117-1.........

95i-21-1 ........

983-110-1 .........

93-110-7.........

985-1,9-10.......

953-121-1........

~4-119-2 .........

955-117-S,........
955-124-, ........

955-125-1.........

9586-129-5........

957-120-1........

957-120-2.........

1: 7-184-1.........

98-1833-2.........

959-128-1.........

000-12-1 ........

001-119-2.........

002-119-1.........


39

23

28.5

5

29

26

6

6.5

7

18

20

36

8

10

46.28

46.88

21

9

12

12

12

31

31

20

25


--- No samples ---

do.



0-77 77-170
I.... ............











--No samples--





0-70 70-148




--- No amoples--


....... .. .. ..
--- 0-104 -


-----------


...........

............




....... ... ,



140-188

110-177

...........

170-218




.. ........



.........
175-185






. ..... ...

............
146-237





200-306



104-222


...... .. .

........ .. ..........
I. ...... ..... .... ...


...... ....... ..

188-270 270-310

177-300 300-330

.,... ... ..

-- 218-265 --

.. ... ... .....




185-250 250-201

....... ..........



237-310 310-351

3.......-335 335-380

... ... ... ..

306-335 338-380

., .,. .


.. ... ....

...........


..........,

...........


. .. ....... .



351-412



.......0-480

380-480

.. ,. ,


. .. .......... .............



........... ,. ........ ..



3 .. 3 0..... .. I ... I. I ...........

....... .., ..1 .. .... ..
310-330 ............ ............

33C-1,440


-191

-177

-191

-182

-230

-108

-182

-170

-178

-202

-210

-202

-181

-175

-198

-193

-218

-228

-264

-294

-316

-191

-200

-227

-250


DI

DI

DI

DI

Dl

DI

C

C, DI

Dl

DI

DI

C, D1

DI

C

El

El

C

DI

Dl

C

DI

C, DI

Dl

Dl

DI


Wai-560












W-237



Wgi-294



............



............

............








W-145



Wgi-612

Wgi-511


--


r
.-1


C


I
ih.





0



to














Sz


.. ....... ...

............


.... I. .

............




.. ...
. ..I .. I..

............





....... ..
480-494


222-436 ----


.... .. .. ..... ..





....... .....

............

......... ...

............
..,,.,,,....


...... ,.,,,..

,,,o,..,,,..,

,,,....,.,...



,.,,,,,,,,.

,,,,.,....,..

.,..,,.......

o,,, .......












TABLE 3.- (Continuled)


Approxi-
I'. M. anlte
(;elogival elevation
Survey of land
well number surfare
(feet)


Depth ill feet below land gurfavu of geoliudie formationsa

in teet
Pleitt I elle Yaoeelle or Ilawtlorn C ryotal Williatlo Inglis A vou Park We ("ity of top of
and I eRaent Plieellne Furnniti' iver Formoation For',nationll .imestone Li eatone Eocene
deposits deposita Forxation I Liniedtone


Florida
(ieologieal
Stol lrre Survey
of datlt well
n nlber


00 3-138-1 ........, 2) 0- 0 40-105 1 -3 .......... ..... ... ....... ..... .. (', W -1
0 10- 123-3 ......... 5 .... ... ... ............ .. .......... ...... .... .. .... ..... ............ -28 1 D I
010-124-1........ 4 ................................ ........... ................ ............ ........... -287 i W-2208

ADJACENT COUNTIES

ALACHUA COUNTY


296-203-I......... ... .......... ............... -.... ................. .. ... ... ... ..
937-203-1......... 135 0-75--- 75-124 124-150 ..................... ........................ +11 C, DI


MARION COUNTY

930-151-1......... 110 ............ .. .......... ................ .. ....... ..... ............ .......... ............ -20 D 1 ...........


I-i






REPORT OF INVESTIGATIONS No. 32


County, Florida. It was later described by Vernon (1951, p. 95) from
outcrops in Citrus and Levy counties, Florida.
The Avon Park Limestone underlies younger Eocene limestones and
overlies the Lake City Limestone in all of Flagler, Putnam, and St.
Johns counties. The contact between the Lake City and Avon Park
Limestones was not well defined in all wells in the area but it was
found to be unconformable in test wells 937-122-1 and 939-134-11. In
these wells the unconformity is marked by rounded pebbles of lime-
stone and dolomite and by thin layers of white to green, calcareous
clay. The Avon Park Limestone ranges in thickness from 155 feet in
well 937-122-1 to 235 feet in well 943-144-1.
Examination of rock cuttings and logs from 16 wells in the area that
penetrate the Avon Park Limestone (table 3) indicates that the lithol-
ogy of the formation varies both vertically and laterally. It generally
grades upward from alternating beds of reddish brown to buff, massive
to granular, peat flecked and seamed limestone and beds of brown to
gray, hard, dense, finely crystalline dolomitic limestone near the base
to a gray to white, chalky limestone streaked with thin beds of hard,
crystalline dolomite near the top. In some wells, particularly west of
the St. Johns River, the formation was found to be more dolomitized.
For example, in well 943-144-1, 6 miles northwest of Palatka (fig. 7)
the formation was found to be almost completely dolomitized and it
contained only a few thin beds of soft limestone near the top.
Some of the limestone beds in the Avon Park Limestone are very
fossiliferous, containing abundant Foraminifera and echinoids. In well
937-122-1, soft limestone beds near the base of the formation are com-
pletely composed of a loose coquina of cone-shaped Foraminifera. The
following characteristic species were identified in the Avon Park Lime-
stone from well cuttings in the area:

Coskinolina floridana Cole
Cribobulimina cushmani Applin and Jordan
Dictyoconus cooked (Moberg)
Dictyoconus gunteri Cole
Peronella dalli (Twitchell)
Spirolina coryensis Cole
Valvulina avonparkensis Applin and Jordan

The lithology of the Avon Park Limestone is similar to that of the
Lake City Limestone. As shown graphically in figures 4 and 5, the Lake
City Limestone and the Avon Park Limestone are characterized by
dense, indurated, relatively impermeable zones which retard the drilling
rate and register a relatively high electrical resistivity. The presence






FLORIDA GEOLOGICAL SURVEY


TEST WELL 943-144-1, 6 MILES NORTHWEST OF PALATKA


0
EXPLANATION
[ Limestone
Eg Dolomite

i- Dolomitic limestone


R P M OF CURRENT METER
Well flowing 440 gpm


Figure 7. Diagram comparing the velocities of water from the different depths ir
the limestones of Eocene age in well 943-144-1.


of these relatively impermeable zones suggests that the water from these
formations comes from several permeable zones that are separated
by the relatively impermeable zones. A deep-well current-meter
traverse in well 943-144-1 gave evidence of separate, relatively per..
meable zones in the Avon Park Limestone. The results of the current.


150 ----


200
'hi

a 250(


,9 300,
SL
350
o

S400



* -
U- 450



a.
UJ
4M


600


650


700oo


750
0 1O
RPM OF
CURRENT METER
Nonflowing well





REPORT OF INVESTIGATIONS NO. 32


meter traverse are shown graphically in figure 7. When the flow of this
well was shut off, there was movement of water within the Avon Park
Limestone in the zone between 430 and 500 feet and between the Avon
Park Limestone and the younger Eocene limestones in the zone be-
tween 300 and 400 feet. This movement shows leakage through the well
bore from zones of higher head to zones of lower head. The zones of
different head are separated by relatively impermeable limestone and
dolomite beds within the Avon Park Limestone which restrict the vertical
movement of water from the more permeable zones within the Avon Park
Limestone and between the Avon Park Limestone and younger Eocene
limestones.

OCALA GROUP
Limestones of late Eocene age in peninsular Florida were defined
by Cooke (1915, p. 117; 1945, p. 53) as the Ocala Limestone.
Vernon (1951, p. 111-171) separated the Ocala Limestone into two
formations: the Ocala Limestone, restricted to the upper part, and the
Moodys Branch Formation. He also divided the Moodys Branch For-
mation into two members: the Williston Member (upper) and the Inglis
Member (lower).
Puri (1953, p. 130; 1957, p. 22-24) redefined the Ocala Limestone,
and changed the Inglis and Williston Members to formational rank,
and changed the Ocala Limestone (as restricted by Vernon) to the
Crystal River Formation. The Inglis, Williston, and Crystal River For-
mations are now referred to as the Ocala Group by the Florida Geolog-
ical Survey. All these formations, as defined by Puri were recognized
in Flagler, Putnam, and St. Johns counties.
Inglis Formation: The Inglis Formation lies unconformably on the
Avon Park Limestone and underlies all the project area. As shown in
figure 8 and in geologic cross sections B-B' and C-C' in figure 6, the Inglis
Formation is the first limestone formation of Eocene age penetrated by
wells in southern Flagler and southeastern Putnam counties. In the re-
mainder of the area, it is overlain by younger Eocene limestone forma-
tions. Where it is overlain by younger Eocene formations it ranges in
thickness from about 60 to 110 feet and averages about 90 feet thick.
In well 919-119-3, in southern Flagler County, the younger Eocene
formations are missing and the Inglis Formation has been thinned by
erosion to a thickness of less than 55 feet.
The Inglis Formation is a tan to buff, coarsely granular, fragmental,
marine limestone. It is generally loosely cemented, porous, and has a
inealy texture. It contains beds consisting entirely of a foraminiferal






FLORIDA GEOLOGICAL SURVEY


coquina of Miliolidae. Locally the formation contains thin beds of in-
durated, finely crystalline limestone and dolomite, and zones of calcite
crystals.
The lithology of the Inglis Formation is similar to the overlying
Williston Formation, and in many sets of well cuttings the upper con-
tact of the Inglis Formation is not clearly defined. In most cases contact
can be closely approximated by differentiating the Inglis and Williston
Formations on the basis of changes in fossil content. Fragments of
Periarchus lyelli and Fabiana cubensis were used as guide fossils (Puri,
1957, p. 48) to identify the Inglis Formation.
The fossils identified in well cuttings from the Inglis Formation
include:
Amphistegina pinarensis cosdeni Applin and Jordan
Fabiana cubensis Cushman and Bermudez
Periarchus lyelli (Conrad)
Spiroloculina seminolensis Applin and Jordan
Williston Formation: The Williston Formation is absent in part of
the project area. As shown on geologic cross sections B-B' and C-C'
in figure 6, it is absent in southern Flagler and in southeastern Putnam
counties. As shown in figure 8, the Williston Formation is the first for-
mation of Eocene age penetrated by wells in most of central and
northern Flagler County, southern St. Johns County, and in most of
east-central and south-central Putnam County. In these areas, the thick-
ness of the Williston has been considerably reduced by erosion. In the
remainder of the area, the Williston is conformably overlain by the
Crystal River Formation and it has not been subject to post deposi-
tional erosion. Where it is overlain by the Crystal River Formation, the
Williston Formation ranges in thickness from about 30 to 50 feet.
The Williston Formation is a tan to buff, granular, fragmental,
marine limestone. It generally can be distinguished from the Inglis For-
mation by its fossil content and by being slightly more indurated and
cemented so that it does not have a mealy texture. Puri (1957, p. 48-50)
found that the Williston Formation contains a distinctive assemblage
of fossils which can be used to differentiate the Williston Formation
from the underlying Inglis Formation and from the overlying Crystal
River Formation. The following species from the Williston Formation
were identified from well cuttings:
Amphistegina pinarensis cosdeni Applin and Jordan
Heterostegina ocalana Cushman
Nummulites vanderstoki Rutten and Vermunt
Operculinoides floridensis Heilprin






REPORT OF INVESTIGATIONS No. 82


Operculinoides jacksonensis Heilprin
Operculinoides moodysbranchensis Gravell and Hanna
Operculinoides willcoxi Heilprin
A few of these species also occur in the Inglis and Crystal River
Formations.
Crystal River Formation: The Crystal River Formation has been
completely removed by erosion in most of eastern Putnam County,
southern St. Johns County, and practically all of Flagler County. In the
remainder of the area it is the first formation of Eocene age penetrated
by wells. As shown in figure 8 and by the geologic cross sections in
figure 6, the upper surface of the Crystal River Formation is very irreg-
ular and the thickness is variable. In general, the formation is thickest
in western Putnam County and in north-central and eastern St. Johns
County and in these areas it ranges in thickness from about 70 to over
100 feet. Where the Crystal River Formation is present it conformably
overlies the Williston Formation.
The Crystal River Formation consists predominantly of white to
cream, massive, soft, chalky, marine limestone. It can usually be dis-
tinguished from the Williston Formation by lithology and fossil content.
The Crystal River Formation is generally less granular and more friable
than the Williston Formation. Generally, it is also more fossiliferous
and contains abundant, relatively large Foraminifera that are not usually
found in the Williston Formation. The following fossils were identified
from well cuttings of the Crystal River Formation:
Fibularia vaughani (Twitchell)
Heterostegina ocalana Cushman
Lepidocyclina ocalana Cushman
Lepidocyclina ocalana pseudomarginata Cushman
Nummulites vanderstoki Rutten and Vermunt
Operculinoides floridensis Heilprin
Operculinoides ocalana Cushman
Operculinoides willcoxi Heilprin
Sphaerogypsina globula (Reuss)

The thickness of the Ocala Group varies considerably in different
parts of the area. As shown by the geologic cross sections in figure 6, the
thickness ranges from less than 50 feet in southern Flagler County,
where only part of the Inglis Formation is present, to approximately
250 feet in eastern St. Johns County, where a complete section of the
Inglis and Williston Formations and much of the Crystal River Forma-
tion remain. The average thickness in the farming areas in eastern Put-
nam and southwestern St. Johns counties is about 150 to 200 feet.






FLORIDA GEOLOGICAL SURVEY


The homogeneous sequence of relatively permeable marine lime-
stone formations that comprise the Ocala Group acts more or less as a
single hydrologic unit. They generally differ from the underlying Lake
City and Avon Park Limestones in that the formations in the Ocala
Group contain few relatively impermeable indurated zones to restrict
vertical movement of water. However, in some areas where the upper
part of the Avon Park Limestone is not separated by impermeable beds,
it is also part of this hydrologic unit. The Ocala Group is capable of
supplying large quantities of artesian water to wells and is the principal
source of water utilized in the area.

HAWTHORN FORMATION
The Hawthorn Formation was originally named by Dall and Harris
(1892, p. 107) for rock exposures in southeastern Alachua County. More
recently Vernon (1951, p. 187) proposed the name Hawthorn Forma-
tion to represent beds of middle Miocene age in peninsular Florida. The
formation was still later described by Puri (1953, p. 16, 39) as the down-
dip facies of beds of middle Miocene age that occur in northwestern
Florida.
The Hawthorn Formation underlies the area except in parts of
southeastern Putnam County and in most of southern Flagler County.
In the areas where it is present the Hawthorn Formation lies uncon-
formably on the eroded surface of the Ocala Group. The unconformity
between Hawthorn Formation and the formations of the Ocala Group
is usually marked by a hard, dense, phosphatic, sandy, dolomitic lime-
stone, averaging about 5 feet thick.
The top of the Hawthorn Formation ranges in altitude from about
100 feet above sea level in western Putnam County to more than 130
feet below sea level in northern St. Johns County. The thickness of the
formation averages about 50 to 100 feet in the farming areas in eastern
Putnam County and southwestern St. Johns County. It increases in
thickness in northern and western Putnam County and northern and
eastern St. Johns County and in these areas it attains a maximum thick-
ness of about 120 to 200 feet.
The Hawthorn Formation consists of gray to green, plastic, phos-
phatic, sandy clay and marl; interbedded with lenses of phosphorite
pebbles, phosphatic sand; and phosphatic, sandy limestone. The sandy
limestone is more prevalent near the base of the formation and appears
to be thickest in western Putnam County and in northern and eastern
St Johns County.






REPORT OF INVESTIGATIONS No. 32


The fauna of the Hawthorn Formation is limited to numerous sharks
teeth found in the clay beds and a few poorly preserved mollusks oc-
casionally found in the sandy limestone.
The lenses of sand and limestone in the Hawthorn Formation yield
moderate amounts of artesian water to some domestic wells in the area.
Along the St. Johns River the lenses seem to be more continuous and
slightly higher yields are obtained here than in the rest of the area.
The clays and marls of the Hawthorn Formation together with those in
the younger deposits serve as confining beds for the artesian water in
the underlying limestone formations of Eocene age and for the artesian
water in the sand and limestone lenses in the Hawthorn Formation.

UPPER MIOCENE OR PLIOCENE DEPOSITS
In most of eastern Putnam County, central and northern Flagler
County, and in all of St. Johns County the Hawthorn Formation is over-
lain by interbedded lenses of marine, fine to medium sand, shell and
green, calcareous, silty clay. In part of southern Flagler County and
southeastern Putnam County where the Hawthorn Formation is absent
these marine beds lie unconformably on the eroded surface of the Ocala
Group. They are described by Vernon (1951, fig. 13; written communi-
cations, January 6, 1943, September 30, 1955, October 3, 1955, October
25, 1956) as late Miocene in age. These upper Miocene deposits were
described by Cooke (1945, p. 214-215, 225) as the Caloosahatchee Marl
of Pliocene age. It was not possible during the present investigation
to determine the exact age of these sediments and in this report they
are classified as upper Miocene or Pliocene deposits.
In western Putnam County the sediments that overlie the Hawthorn
Formation are nonmarine or near-shore deposits that consist of undif-
ferentiated beds of coarse, poorly sorted sand; kaolin, and variegated
sandy clay. The variegated clays that are commonly exposed in roadcuts
and excavations were classified by Cooke (1939; 1945, p. 229-231, 236)
as the Citronelle Formation of possible Pliocene age. Vernon (1942)
classified the Citronelle Formation as Pleistocene in age. These non-
marine or near-shore beds are discontinuous and cannot be differenti-
ated lithologically for any great distance and they contain no recogniz-
able fossils to indicate their age. They are therefore referred to in this
report as post-Hawthorn to Recent deposits.
In most of the area the nonmarine or near-shore sediments and the
marine sediments unconformably overlie the Hawthorn Formation. The
conformityy is marked by a zone of rounded, black phosphorite and
rounded, coarse sand. However, in a number of wells in northeastern






FLORIDA GEOLOGICAL SURVEY


Flagler County and in northern and eastern St. Johns County, the con-
tact between the Hawthorn Formation and the overlying marine, upper
Miocene or Pliocene deposits is not clearly defined and appears to be
gradational.
As shown on the geologic cross sections in figure 6, the thickness of
the marine, upper Miocene or Pliocene deposits ranges from about 20
to 100 feet. The average thickness in the farming areas in eastern Putnam
and southwestern St. Johns counties is about 30 to 50 feet. The com-
bined thickness of the post-Hawthorn to Recent deposits in western Put-
nam County ranges from about 10 to 130 feet.
The marine, Miocene or Pliocene deposits contain mollusks, echinoid
spines, and well preserved Foraminifera. The following species were
identified in well cuttings in the area:
Amphistegina lessonii (d'Orbigny)
Elphidium incertum (Williamson)
Lagena costata amphora Reuss
Oolina hexagona (Williamson)
The upper Miocene or Pliocene sand and shell beds yield moderate
amounts of artesian water to wells. A large portion of the municipal
water supply for the cities of St. Augustine and Bunnell and a portion
of the water supply for the city of Palatka are obtained from wells in
these deposits. Discontinuous, medium to coarse-grained sand beds in
both the nonmarine or near-shore, post-Hawthorn to Recent deposits
and in the marine, upper Miocene or Pliocene deposits supply small to
occasional large amounts of nonartesian water to domestic wells. The
relatively impermeable clays and sandy clays in these deposits, together
with those in the Hawthorn Formation, serve as confining beds for the
artesian water in the underlying limestone formations of Eocene age
and the thin, lenticular sand, shell and limestone beds above the Eocene
limestone.

PLEISTOCENE AND RECENT DEPOSITS
The sediments that blanket the surface of Flagler, Putnam, and St.
Johns counties are Pleistocene and Recent in age. As shown on the
geologic cross sections in figure 6, they range in thickness from less than
20 feet in southern and central Flagler County to about 140 feet in
western Putnam County.
The Pleistocene deposits consist of fine to medium quartz sand and
thin lenses of clay and shell in the eastern part of the area and fine to
coarse poorly sorted sand and sandy clay in western Putnam County
The beds are generally discontinuous and the lithology and texture of






REPORT OF INVESTIGATIONS No. 32


the deposits may vary considerably within short distances both later-
ally and vertically. The shell beds thicken along the coast and locally
have been more or less firmly cemented to form a coquina. The coquina
and loose, aggregate sand and shell beds that are at or near the surface
along the coast from about St. Augustine southward through Flagler
County have been mapped by Cooke (1945, p. 1) and assigned to the
Anastasia Formation (Cooke, 1945, p. 265-268, 272). According to
Cooke, the formation rarely extends inland more than 3 miles beyond
the Intracoastal Waterway. During the current investigation similar
shell beds were found about 5 miles inland in east-central St. Johns
County and 8 miles inland in east-central Flagler County.
The undifferentiated Recent deposits consist of alluvial sand and
clay in the present stream valleys, dune sand along the coastline, and
isolated peat deposits in the lakes and marshes.
Medium to coarse-grained sand and shell beds within the Pleisto-
cene to Recent deposits locally supply moderate amounts of water to
screened wells. The shallow nonartesian water is an important source
of water in those areas where the artesian water is too highly mineral-
ized for use. The municipal water supply for Flagler Beach is obtained
from wells completed in these deposits. A part of the municipal water
supply for St. Augustine and many rural domestic supplies are obtained
from these deposits.
STRUCTURE
The approximate areal extent of the Inglis, Williston, and Crystal
River Formations and the structural contour lines showing the altitude
and configuration of the surface of the Ocala Group are shown in figure
8. As indicated on the map, in areas where the Williston and Crystal
River Formations are absent the contour lines represent the top of the
Inglis Formation; where the Crystal River Formation is absent, the
contour lines represent the top of the Williston Formation; where the
Crystal River Formation is present, the contour lines represent the
altitude of its upper surface. The map was constructed on the basis of
information from electric logs, and the study of well cuttings (table 3).
The top of the Ocala Group is an irregular surface and it is more
irregular than can be shown on this generalized map, particularly in
western and southeastern Putnam County where numerous sinkholes
are known to exist. The top of the Ocala Group ranges in depth from
about sea level in southwestern Putnam County to more than 300 feet
below sea level in northern St. Johns County. The depth to limestone
,.t any specific location in the area may be obtained by using the struc-
tural contours in figure 8 in conjunction with the land-surface altitude.






84 FLORIDA GEOLOGICAL SURVEY

The structural contour lines in figure 9 show the altitude and con-
figuration of the surface of the Inglis Formation in the area. The sur-
face of the Inglis Formation is not eroded except in southern Flaglel
and southeastern Putnam counties (fig. 9). In these areas the contour

5 .o" 3 s o '_______3,

EXPLANATION4 {N




'3,4I350




ouse ,a 3.
S 9 ...,,-wt tMle Inotl --r .ati on a

zoo---- : \ ,'v -'---










'F- 1- -. ?"IWO'N,










-, .F"" =.-- *-o3,.
U ,- r lh do, 32





203 33 3E3

















Figure 9. Flagler, Putnam, and St. Johns counties showing the altitude of the top
of the Inglis Formation.


lines are projected to represent the approximate altitude of the top of
the formation before erosion. The contour lines constructed on the
uneroded surface of the Inglis Formation show the true dip and strike
of the formation, and the configuration of the lines show the subsurface
structure unmodified by erosion.
L-,7-




t ; IFlo






Fr "A
0 C
UJI ;!-.50
Figre9 lalr Pta, n t.Jhs onie hwigte liud fth o
of the nglis Frmation
lie aepojce t epeet h ppoiat lttd o h tpo
thefomaio bfoe roio. hecotor ins ontrctd n he






REPORT OF INVESTIGATIONS No. 32


A north-south fault passes through Lake George and extends north-
ward into north-central Putnam County (fig. 8, 9). In the vicinity of
Welaka, the vertical displacement of the top of Eocene limestone is
about 50 feet and the top of the Inglis Formation is about 75 feet.
The vertical displacement decreases northward and where the fault
intersects Etonia Creek in north-central Putnam County the vertical
displacement of the top of the Eocene limestone is less than 20 feet and
of the top of the Inglis Formation is about 35 feet (fig. 6, geologic cross
section A-A').
As shown on figure 9 the general configuration of the surface of the
Inglis Formation differs west and east of the fault. West of the fault
the surface of the Inglis Formation roughly strikes northwest-southeast
and dips northeastward from southwestern Putnam County at an
average of about 9 feet per mile. East of the fault, the formation roughly
strikes east-west and dips northward from southern Flagler and south-
eastern Putnam counties. East of the fault the rate of dip increases
northward, averaging less than 5 feet per mile through Flagler County
and about 9 feet per mile through St. Johns County. In the structurally
high area in southern Flagler and southeastern Putnam counties, the
geologic cross sections B-B' and C-C' (fig. 6) indicate that the Inglis
Formation has been thinned and the Williston and Crystal River For-
mations have been entirely removed by erosion.
A comparison of the structural contours in figures 8 and 9 shows that
the configuration of the Ocala Group roughly reflects the configuration
of the Inglis Formation, but the surface of the Ocala Group is more
irregular and the slope may vary considerably in gradient and direction
within a relatively short distance. The thickness of the Williston and
Crystal River Formations may be obtained at any specific location in
the area by comparing the structural contours in figures 8 and 9. The
thickness of the Inglis Formation generally averages about 90 feet. The
combined thickness of the Ocala Group can then be estimated by using
the average thickness of the Inglis Formation and the thickness of the
Williston and Crystal River Formations from figures 8 and 9. In areas
where only part of the Inglis Formation remains, its thickness can be
estimated by subtracting the actual surface altitude contours in figure 8
from the projected contours in figure 9.
GEOLOGIC HISTORY
The relative age of the sediments in Flagler, Putnam, and St. Johns
counties can be determined by their stratigraphic position in respect to
associated rocks. The oldest beds occur at the greatest depth and the
youngest beds are closest to the surface.






FLORIDA GEOLOGICAL SURVEY


The oldest rocks usually penetrated by water wells in the area were
deposited during the Eocene Epoch. The Lake City Limestone, Avon
Park Limestone, and the Ocala Group were deposited by separate
but similar inundations of early middle to late Eocene seas. The absence
of plastic material and the abundance of Foraminifera in these forma-
tions indicate that deposition was in relatively warm, shallow, open seas.
According to Cooke (1945, fig. 4, p. 46, 51-52, 57) most of Florida was
submerged at the time these sediments were deposited. The unconform-
able contacts between the Lake City Limestone and the Avon Park
Limestone, between the Avon Park Limestone and the Ocala Group,
and between the Ocala Group and the overlying sediments give
evidence that the inundations of the sea were separated by periods of
emergence. During these periods of emergence the formations were
partly or completely removed by erosion. The period of emergence
that exposed the top of the Ocala Group to erosion marked the end of
the Eocene Epoch in the area.
The absence of rocks of Oligocene and early Miocene age in well
cuttings may indicate that either the area remained above sea level
during this time and these sediments were not deposited or that erosion
before the middle Miocene time completely removed all vestiges of
these rocks. Geologic cross sections B-B' and C-C' in figure 6 show that
in central and northern Flagler County, southern St. Johns County, and
in southern Putnam County the contact between the top of the Ocala
Group and the overlying middle Miocene Hawthorn Formation is an
angular unconformity. This evidence indicates that structural move-
ment occurred after the Eocene Epoch and before middle Miocene
time in these areas.
In middle Miocene time the seas again invaded most of the eastern
part of the Florida Peninsula (Vernon, 1951, p. 181-184) as well as most
or all of Flagler, Putnam, and St. Johns counties. The sediments were
deposited on the eroded surface of the Ocala Group in the area, and
the fine plastic nature of these sediments indicates that they were
deposited near shore by relatively shallow seas. The middle Miocene
sediments are absent in most of southern Flagler County and in part of
southeastern Putnam County except in a few isolated low areas or sink-
holes (geologic cross sections B-B' and C-C' in fig. 6). This, indicates
that either this area was structurally high during middle Miocene time
and deposition occurred in only a few isolated depressed areas or that
the middle Miocene sea extended into the area and the sediments were
subsequently removed by erosion. After the middle Miocene sediments
were deposited the sea retreated from most or all of the area and
exposed the sediments to erosion.







REPORT OF INVESTIGATIONS No. 32


Erosion after middle Miocene time scoured the original relatively
regular and level surface of the sediments. However, the geologic cross
sections in figure 6 reveal that in addition to being scoured by erosion
in most of the area, the present general configuration of the upper sur-
face of the Hawthorn Formation of middle Miocene age tends to re-
flect the configuration of the upper surface of the Ocala Group. This
may be attributed to structural deformation after middle Miocene time.
Much of this structural deformation was probably caused by slumpage
of the middle Miocene and Eocene sediments into sinkholes that were
formed by circulating ground water. Vernon (1951, p. 29-31, 62) rec-
ognized the possible post-Miocene structural movement in the Florida
Peninsula that may have caused some of the structural deformation in
the area. A structural uplift after middle Miocene time would explain
the removal of the middle Miocene deposits in the southeastern part
of the area, if the middle Miocene seas were later proven to have
extended into that area.
The approximate age of the fault in central Putnam County can be
established from geologic cross sections A-A' and C-C' in figure 6. The
geologic cross sections show that the fault displaces beds of late Eocene
age but probably does not cut middle Miocene sediments. Therefore,
the fault developed later than Eocene and probably earlier than the
end of middle Miocene time.
Late Miocene or Pliocene seas inundated the entire eastern and
central parts of the area and deposited marine sediments on the eroded
surface of the underlying rocks. The absence of these marine sediments
in western Putnam County indicates that either this area remained
above sea level during late Miocene or Pliocene time or the sea
extended into this area and the sediments were removed by post-
depositional erosion. The exact age of the coarse, plastic, nonmarine
sediments directly overlying the Hawthorn Formation in western Put-
nam County is not determined in this report. According to Cooke (1945,
p. 231-236) the nonmarine sediments in western Putnam County that
overlie the Hawthorn Formation may possibly be the near-shore and
beach deposits of the seas that deposited the marine beds overlying
-he Hawthorn Formation in the remainder of the area. As the marine
beds above the Hawthorn Formation are now called late Miocene or
?liocene in age, the nonmarine deposits in western Putnam County. may
hen in part also be late Miocene or Pliocene in age.
The Pleistocene Epoch was a time of alternate glaciation and
'eglaciation. The times of glaciation are called glacial ages and the
times of deglaciation are called interglacial ages. Advance of the







FLORIDA GEOLOGICAL SURVEY


glaciers lowered sea level by storing volumes of the earth's water as ice.
During the interglacial ages, the melting glaciers returned water to the
sea, thereby causing sea level to rise. A shoreline and corresponding
marine terrace developed whenever the sea remained long enough at
one elevation. Eight marine shorelines have been recognized in Florida
(Cooke, 1945, p. 248; Cooke and Parker, 1944, p. 24) and have been
tentatively correlated to the glacial and interglacial ages. Seven of these
terraces have been mapped (fig. 3) and described (p. 8 to 11) in
the area. The following table shows the Pleistocene terraces in the area,
the approximate altitude (in feet) of their shoreline, and their tentative
age:

TAmLE 4. Pleistocene Terraces in Flagler, Putnam, and St. Johns Counties
Approximate altitude
Terrace of shoreline (feet) Tentative age
Coharie 215 Yarmouth
Sunderland 170
Wicomico 100 Sangamon
Penholoway 70
Talbot 42
Pamlico 25 Interglacial recession in
Wisconsin glacial
Silver Bluff 5-10 Interglacial recession in
Wisconsin glacial or
Recent


The highest and oldest terrace in the area, the Coharie, was formed
near the beginning of the Yarmouth Interglacial Stage. During that
time the sea stood 215 feet above present sea level and covered most of
peninsular Florida. The remnants of this terrace in western Putnam
County were probably shoals in the Coharie sea and the small sandhills
on the top of these remnants were probably bars that stood above the
Coharie sea. Later in Yarmouth time the sea stood at a height of about
170 feet above present sea level and the Sunderland terrace was
formed. The shoals that were formed in western Putnam County in
Coharie time were islands in the Sunderland sea. The Sunderland ter-
race developed around the fringes of these islands and shoals and bars
developed farther offshore, as far east as eastern Putnam County.
A period of glaciation followed the Yarmouth Interglacial Stage and
the sea dropped to an undetermined low level. The glaciers then re-
treated during the Sangamon Interglacial Stage and the seas again ad-
vanced over most of the Florida Peninsula. They remained relatively







REPORT OF INVESTIGATIONS No. 32


stationary at altitudes of 100, 70, and 42 feet and the Wicomico, Pen-
holoway, and Talbot terraces, respectively, were formed. The older ter-
races that were formed in western Putnam County during Yarmouth
time were part of the mainland near the beginning of Sangamon time
and the terraces and shoals in eastern Putnam County were offshore
islands. Each of the younger and lower terraces of Sangamon time were
Progressively formed on the seaward side of the mainland and around the
fringes of the islands. In addition, each terrace formed sea-deposited
offshore shoals which in turn became islands during subsequent lower sea
, invasions. In this manner the mainland was progressively built up and the
islands became progressively larger and more numerous. Near the close
Sof Sangamon time, when the Talbot terrace was being formed, the main-
Sland in the project area extended as far eastward as about the present
St. Johns River and a large shoal covered most of what is now St. Johns
and Flagler counties.
The Wisconsin Glacial Age that followed Sangamon time again
lowered the sea to an undetermined low level. During middle Wiscon-
sin time, a recession of the ice raised the sea to about 25 feet higher
than its present level and the Pamlico terrace was formed. The Pamlico
sea advanced 2 to 5 miles inland of the present coastline of St. Johns
and Flagler counties. The shoal that was formed in Talbot time in
central St. Johns and central Flagler counties remained above sea level
Sand the area that is now occupied by St. Johns River and Crescent
SLake was part of a larger estuary that covered eastern Putnam County
and western St. Johns and western Flagler counties. At a later period,
either during another recession of the ice in Wisconsin time (Cooke,
1945, p. 48), or during the early part of Recent time (Parker, 1955,
p. 24-25) the sea level remained relatively stationary at about 5 to
10 feet above its present level and the Silver Bluff terrace was formed.
The Silver Bluff sea advanced less than 1 to over 4 miles landward of
Sthe present coastline of St. Johns and Flagler counties and formed a
marine terrace along the coast. In eastern Putnam County and western
St. Johns and western Flagler counties, the contracted estuary that was
originally formed in Pamlico time eroded the Pamlico terrace to base
Level and terraces were formed that correspond in height to the marine
Silver Bluff terrace along the coast.
The Anastasia Formation that is present along the present coastline
Sof St. Johns and Flagler counties was probably an offshore bar that was
deposited at the same time the Pleistocene terraces were formed farther
inland. According to Cooke (1945, p. 266) the Anastasia Formation
w- may have been alternately deposited and eroded during most or all of
the Pleistocene Epoch.






FLORIDA GEOLOGICAL SURVEY


At the beginning of Recent time the ice receded and the sea was
established at approximately its present level. The sand dunes along
the coast, the peat and muck in lakes and marshes, and the alluvium
along the various streams are presently being deposited in the area.

GROUND WATER
Ground water is defined as the water in the zone of saturation-the
zone beneath the earth's surface in which all the interstices of the rocks
are filled with water which is free to move under the influence of
gravity.
Ground water occurs in reservoir systems that are capable of accept-
ing, storing, and transmitting water. These reservoir systems are com-
posed of a collection of interconnected, porous, relatively permeable
zones called aquifers, and continuous, relatively impermeable zones
called aquicludes. The aquifers serve as conduits that distribute and
store water, and the aquicludes serve to separate aquifers as well as
store some water. Smaller impermeable zones are herein called con-
fining beds because they serve to confine ground water locally in an
aquifer. An aquifer and its associated confining beds and aquicludes
constitute an aquifer system.
Ground-water reservoir systems are classified as either nonartesian
or artesian. Nonartesian reservoir systems accept and store recharge
water by allowing water to infiltrate and fill previously unsaturated
voids throughout the extent of the aquifer. Artesian reservoir systems
are recharged in areas where the aquifers crop out at the surface and
in areas where the aquicludes have been breached by erosion or pene-
trated by sinkholes through which water passes freely to the aqui-
fer. Additional water may be stored in the already saturated pore
spaces through a process of simultaneous compression of the water and
expansion of the reservoir.
Ground water always exists under hydrostatic pressure, but its
movement is always from places of higher potential or head to places
of lower potential or head. Its head at any point can be expressed as
the altitude above a fixed datum to which it will rise in a tightly cased
well. The horizontal distribution of head in an artesian aquifer is shown
by piezometric maps and in a nonartesian aquifer by water-table maps
which have contour lines joining points of equal head. The difference
in head in an aquifer between two given points is usually expressed in
feet of water. The slope of the profile of head change between them is
called the hydraulic gradient, generally expressed in feet per mile.
Ground water moves, under the influence of the hydraulic gradient,






REPORT OF INVESTIGATIONS NO. 32


from areas of recharge to areas of discharge. The velocity of ground-
water movement depends primarily upon the hydraulic gradient and the
permeability of the media through which the water passes. Because
ground water moves more or less laterally in aquifers, the piezometric
and water-table maps can be used to determine the rate of ground-water
flow if the permeability and thickness of the aquifer are known.
Precipitation on the earths' surface undergoes one of several proc-
esses that will ultimately return it to the atmosphere: part of this wa-
ter will be evaporated at the surface and return to the atmosphere;
part will run off the land areas into lakes and streams to supply surface
water bodies; and part will soak into the ground and begin to percolate
downward toward the zone of saturation. Some of the water that enters
the soil is taken up by plants and transpired into the atmosphere,
some is evaporated from the soil, and some reaches the water table to
become part of the ground-water supply. After the water reaches the
zone of saturation it begins to move under the influence of gravity to
areas of lower head. This movement is generally laterally toward areas
of discharge. This cycle of water movement is termed the hydrologic
cycle and it may take a few hours or thousands of years to complete
the entire cycle. Figure 10 diagrammatically shows this hydrologic
cycle.
Ground water may be divided into two general classes: that which
occurs in the shallow formations, mostly under nonartesian conditions,
and that which occurs in the deeper deposits under artesian conditions.
Nonartesian conditions are those in which ground water is unconfined,
so that its upper surface (the water table) is free to rise and fall.
Artesian conditions are those in which the ground water is confined in
a permeable formation that is overlain by a relatively impermeable for-
mation, so that its surface is not free to rise and fall, and the water is
under sufficient pressure to rise in wells above the top of the formation
that contains it. The imaginary surface to which water will rise in
tightly cased wells that are open to the artesian aquifer is called the
piezometric surface.
Nonartesian aquifer: The relative average permeabilities of the post-
Eocene deposits in Flagler and St. Johns counties are shown in figure
11. The nonartesian aquifer is the surficial deposits of relatively low
and high average permeability that overlie the uppermost, more or less
continuous system of deposits of very low average permeability.
As may be seen from figure 10, the nonartesian aquifer extends from
Sthe surface to a maximum depth of at least 150 feet below the land
surface. It occurs over the entire project area and includes deposits of






FLORIDA GEOLOGICAL SURVEY


Miocene or Pliocene age and the deposits of Recent and Pleistocene
age in the eastern part of the area and post-Hawthorn to Recent de-
posits in western Putnam County. It rests upon clay or marl of the
Hawthorn Formation or upper Miocene or Pliocene deposits. Generally,
ground water in the nonartesian aquifer is under sufficient head to rise
within a few feet of the land surface.




?i fl a 0 U Evipa o l on



too SURFACE "e F.....
4"- ell-
F LORIAFE A








-700





Figure 10. Diagram showing the generalized hydrologic conditions in northeastern
Florida.

The nonartesian aquifer will probably not be utilized for irrigation
supplies during the next decade because of the heterogeneous and fine
texture of the deposits, and the relatively small thickness of the water-
bearing zones. These factors would make the cost of installing wells
and pumping water greater than the costs for wells tapping the deeper
Floridan aquifer in areas of natural artesian flow. However, the non-
artesian aquifer is of more than minor importance in certain coastal
areas in Flagler and St. Johns counties where the underlying artesian
reservoir contains water of poor chemical quality, and there is a rapidly
growing demand for small domestic supplies of ground water. There-






REPORT OF INVESTIGATIONS NO. 32


fore, the nonartesian aquifer has been studied in some detail in these
coastal areas.
Deposits of high average permeability: The continuous system of
relative high average permeability deposits shown by the cross sections
in figures 11 and 13 constitutes the major water-producing zone of the
nonartesian aquifer.
These deposits attain a maximum thickness of about 100 feet, along
the coast in eastern portions of Flagler and eastern St. Johns counties
between St. Augustine and Flagler Beach. As shown by the cross sec-
tions in figures 11 and 13 and by the contours in figure 12, they grad-
ually thin from the coast westward to the St. Johns River or to where
they pinch out against the underlying deposits of low average perme-
ability. The outcrops of deposits of low average permeability in the
area have been mapped in some detail by the U.S. Department of
Agriculture (1917 and 1918) and by Matson and Sanford (1913, pl. 1)
as a sandy shell marl, and are shown in figure 12.
Along the coast, south of St. Augustine, the nonartesian aquifer is
generally coarse textured, consisting of thick beds of shell of the Anastasia
Formation. As shown in figure 13, the amount of shell decreases a few
miles west of the coastline and the aquifer consists mostly of sand with
a few shell beds confined to the lower part. In Flagler County, exten-
sive shell beds are found as far west as Bunnell.
The nonartesian aquifer is principally replenished by local rainfall.
Relatively impermeable beds of hardpan or marl found in the deposits
of high average permeability are not continuous and there is an ab-
sence of extensive perched water-table conditions. Therefore, extensive
permanent swamps in northern Flagler and southern St. Johns counties
are probably not a result of impermeable beds impeding the infiltra-
tion of rain, but rather a result of the aquifer being filled to capacity.
A few relatively impermeable beds, strategically located and local
in occurrence, are important because they partly control the movement
and consequently the quantity and quality of water available to wells.
For example, the relatively impermeable deposits that are about 40 feet
below land surface in wells 933-116-1, 933-110-1, 940-112-1, and 928-108-5
(fig. 11) were also described by Matson (1913, p. 417) as occurring at a
depth of 35 to 56 feet below land surface in coastal areas of Volusia
County. This impermeable bed might act as a barrier to the upward
movement of underlying salt water, thereby preventing contamination of
fresh ground-water supplies above the impermeable bed. However, the
occurrence of an impermeable bed at an elevation of about 10 feet below
sea level at well 933-110-1 may confine the underlying ground-water








FLORIDA GEOLOGICAL SURVEY


0

50

100

150

200

- 250

l300







50
50

100
LL-
I O







200


z


L-

10
_0
uJ 0
O


Figure 11. Cross section showing distribution of permeability in the post-Eocene
deposits of Flagler and St. Johns counties.


c,
0
A






REPORT OF INVESTIGATIONS No. 32


Figure 12. Flagler, Putnam, and St. Johns counties showing the altitude of the base
of material of high average permeability and the approximate outcrop area of
material of low average permeability.
under artesian pressure. The cone of influence of a well pumping in
this zone would tend to expand rapidly eastward and induce ocean wa-
ter into the pumped zone.
Deposits of low average permeability: Deposits of low average per-
meability occur in post-Eocene deposits throughout all Flagler, Putnam,
and St. Johns counties (fig. 11, 12). Generally, small to moderate
amounts of water may be obtained from these deposits.
In the eastern part of Flagler and eastern St. Johns counties, these
deposits are in only the lower part of the nonartesian aquifer and are














A A,


... .
;, '5 A 0 1) 1 F E" i i







S .-.- V. l-:-. :--w vege pem ... y
4 aw ",. :... :.:..... ..: .' I.

IE I .A N























Figure 13. Cross section showing distribution of permeability, lithology, and electrical and water-bearing characteristics of the depos-
its between Hastings and St. Augustine.
Veyloliwly avea poab irlllly







Figure 13. Cross section showing distribution of permeability, lithology, and electrical and water-bearing characteristics of the depos-
its between Hastings and St. Augustine.






REPORT OF INVESTIGATIONS No. 82


below the deposits of high average permeability. In this area, the aqui-
fer consists of discontinuous lenses of permeable, medium to fine sand
and limestone within marl and clay beds in the lower part of the
Pleistocene and Recent deposits, the upper Miocene or Pliocene de-
posits and occasionally in the upper part of the Hawthorn Formation.
The permeable zones are generally less than 20 feet thick and many
wells obtain water from more than one zone. For example, well 930-
180-1 obtains water from permeable zones between 40 to 60 feet and
between 80 to 100 feet below land surface, well 924-122-6 obtains water
from between 20 to 30 feet and between 40 to 45 feet below land sur-
face, and well 919-128-2 obtains water from a few feet of permeable
rock at about 40 to 80 feet below land surface. Water from deposits of
low average permeability in the nonartesian aquifer may be obtained
as deep as 80 to 150 feet below sea level along the coast south of Cres-
cent Beach.
In western Flagler and western St. Johns counties (fig. 11, cross sec-
tions B-B', C-C', and D-D', fig. 12, 13) and in most of Putnam County
(unmapped) the deposits of low average permeability are at or near
the surface and the deposits of high average permeability are either
negligible in thickness or absent. In these areas deposits of low average
permeability constitute almost the entire nonartesian aquifer and are
the only source of water for shallow wells.
The nonartesian aquifer in western Flagler and western St. Johns
counties and in eastern Putnam County consists of relatively continuous
porous zones of medium to fine sand in the Pleistocene and Recent de-
posits, upper Miocene or Pliocene deposits in the post-Hawthorn to
Recent deposits. In the hilly uplands in western Putnam County, the
permeable zones may be over 100 feet thick in areas of higher eleva-
tion. However, the saturated thickness of the aquifer is considerably
less than 100 feet because the water table is relatively deep in these
areas. In some of the valleys in western Putnam County, the thickness
of the nonartesian aquifer is negligible because the principal aquiclude
is near the surface (fig. 6, geologic cross section A-A').
The deposits of low average permeability are recharged by local
rainfall where the deposits are at or near the surface in western Flagler
and western St. Johns counties and in Putnam County. In eastern
Flagler and eastern St. Johns counties the deposits are recharged by
water infiltrating down from the overlying deposits of high average
permeability.
Most of the shallow wells in the area that utilize these deposits are
either jetted or the casing is driven until water is obtained. This type






FLORIDA GEOLOGICAL SURVEY


of well construction makes it difficult to locate and develop many of the
thin, porous, water-producing zones. Properly constructed and devel-
oped wells should succeed in producing small to moderate supplies by
utilizing more of the thin water-bearing zones in the deposits of low
average permeability.
ARTESIAN RESERVOIR
The artesian reservoir includes the principal aquiclude, the second-
ary artesian aquifers, and the Floridan aquifer. The uppermost limit of
the artesian reservoir is the base of the deposits of very low average
permeability which coincide with the base of the nonartesian aquifer.

OCCURRENCE OF AQUICLUDES AND AQUIFERS
The principal aquiclude consists of marl, clay, and dolomite beds
in the Hawthorn Formation and in the late Miocene or Pliocene de-
posits. These deposits restrict vertical movement of water to and from
the artesian aquifers. As shown on the geologic cross sections in figure 6
the upper surface of these deposits ranges in elevation from about 50
feet below sea level to 100 feet above sea level. The deposits are over
200 feet thick in central Putnam County and in northern St. Johns
County.
Thin discontinuous lenses of limestone, shell, and sand occur within
the aquiclude and form the secondary artesian aquifers. The thick sec-
tion of limestone of Eocene age that underlies the principal aquiclude
is the Floridan aquifer. The altitude and configuration of the top of the
limestone of Eocene age (Floridan aquifer) in Flagler, Putnam, and
St. Johns counties are shown in figure 8.
Secondary artesian aquifers: The secondary artesian aquifers are
composed of lenses of sand, shell, and limestone that occur within the
principal aquiclude. These aquifers include both the Hawthorn Forma-
tion and upper Miocene or Pliocene deposits. The aquifers range from
less than 10 to about 800 feet below sea level, and vary in thickness
from less than 1 to about 15 feet. They are most prevalent east of the
St. Johns River and in north-central Putnam County where the princi-
pal aquiclude attains maximum thickness.
The secondary artesian aquifers are recharged from at least two
different sources: from the overlying nonartesian aquifer and from the
underlying Floridan aquifer. Near St. Augustine, well 952-120-2 was
completed in a secondary artesian aquifer in relatively shallow upper
Miocene or Pliocene deposits, and the water-level fluctuations in this
well correlated with the rainfall at St. Augustine (fig. 14). Water levels
in this well rise in response to local rainfall and decline during dry







REPORT OF INVESTIGATIONS No. 32


w 30
29
D: Well 952-120-2
S28-
< completed in the
secondary artesian
26 aquifer.

25
24
23
22
21
14
r 12
O St Augustine _
z 0
z 8

-J
LL
2 2

0 JFMAMJJASONDJFMAMJJASONDJFMAMJJASOND
1956 1957 1958

Figure 14. Graphs showing the rainfall at St. Augustine and water levels in well
952-120-2, secondary artesian aquifer; well 954-129-1, secondary artesian aquifer;
and well 955-125-1, Floridan aquifer.






FLORIDA GEOLOGICAL SURVEY


periods. The chloride content of water from this well averages about
30 ppm, whereas the chloride content of water from wells tapping the
Floridan aquifer in the same area is about 600 ppm (figs. 33, 34). There-
fore, water in the secondary artesian aquifer tapped by well 952-120-2
probably is being replenished from the overlying nonartesian aquifer
which in turn is recharged directly by rainfall. Recharge into the second-
arv artesian aquifers probably occurs locally where either the nonarte-
sian and secondary artesian aquifers are interconnected or by downward
leakage through the aquiclude in areas where the water level in the
nonartesian aquifer is higher than the water level in the secondary
artesian aquifers.
Water-level fluctuations in the relatively deep secondary artesian
aquifers and in the Floridan aquifer are usually similar. This is shown
in figure 14 by comparing the fluctuations of water levels in well 955-
125-1, completed in the Floridan aquifer, with those in well 954-129-1,
completed in a secondary artesian aquifer in the Hawthorn Formation.
The secondary artesian aquifer in the vicinity of well 954-129-1 is prob-
ably being replenished from the underlying Floridan aquifer by up-
ward leakage or both aquifers are directly connected together. In many
areas, particularly where the aquiclude is relatively thin, water in the
secondary artesian aquifers is replenished by water from both the non-
artesian and Floridan aquifers.
The secondary artesian aquifers are an important source of water in
eastern Flagler and eastern St. Johns counties where water from the
Floridan aquifer is too highly mineralized for domestic use and only
small quantities of water can be obtained from the overlying non-
artesian aquifer. Wells are usually not completed in the deeper second-
arv artesian aquifers because greater quantities of the same type of
water can usually be found a few feet deeper in the Floridan aquifer. The
chemical quality of the water in some of the secondary artesian aqui-
fers, particularly near the base of the aquiclude, is similar to the water
in the Floridan aquifer.
Floridan aquifer: The Floridan aquifer is the major source of water for
irrigation, public supply, and industry in the area. The aquifer has a
vital bearing on the economy of the area; thus, most of the information
collected and studied during this investigation concerned the Floridan
aquifer.
The Floridan aquifer underlies all of Florida and the southern part
of Georgia. Stringfield (1936, p. 125-132, 146) described the aquifer
and mapped the piezometric surface of artesian water in 1933 and
1934. The aquifer is composed of several limestone formations of Eocene,







REPORT OF INVESTIGATIONS No. 32


Oligocene, and Miocene age that act more of less as a single hydro-
logic unit. In Flagler, Putnam, and St. Johns counties the Floridan
aquifer consists of limestone formations of Eocene age and permeable
beds in the lower part of the Hawthorn Formation that are in hydrologic
contact with the rest of the aquifer.
Water in the Floridan aquifer is replenished only in areas where the
water table stands higher than the piezometric surface. It is transmitted
to the aquifer by two processes: (1) In part of the area, principally in
western and southeastern Putnam County the aquiclude is breached by
sinkholes, and water is transmitted directly to the aquifer through these
breaches; and (2) in other parts of the area, principally in Flagler
County, where the principal aquiclude is either thin or absent, water
from the nonartesian aquifer enters the artesian aquifer by downward
leakage through the aquiclude. The volume of water transmitted in this
manner is dependent upon the head difference between the water
table and the piezometric surface and the thickness and permeability
of the aquiclude.
From the recharge areas water moves laterally through the pores
and cavities in the limestone toward areas where discharge is occurring.
Water is discharged from the artesian aquifer in the areas by springs,
wells, and upward percolation of water to the nonartesian or secondary
artesian aquifers.
Fluctuations of water levels: The objectives of observing water-level
changes in wells in the area were to locate, areas of detrimentally high
or low ground-water levels, to facilitate the prediction of trends of
ground-water levels, and to delineate short-term fluctuations from long-
term trends.
The water level in artesian wells fluctuates in response to recharge,
discharge, earthquakes, passing trains, earth tides, ocean tides, and
variations in atmospheric pressure. The greatest fluctuation observed
in the area was caused by seasonal discharge due to pumping of water
for crop irrigation and industrial purposes and variation in recharge
due to rainfall. Smaller fluctuations were caused by ocean tides, earth
tides, changes in atmospheric pressure, and earthquake waves.
Water levels in 60 wells penetrating the Floridan aquifer in the area
were measured periodically and the water levels in six wells were
measured continuously with a recording gage for the 8-year period,
1956-59. In addition, nine wells have been measured periodically since
1936.
Fluctuations caused by rainfall: Fluctuations in response to rainfall
are especially significant because they indicate the extent to which the







52 FLORIDA GEOLOGICAL SURVEY

aquifer is being recharged. In recharge areas the water levels in artesian
wells respond very rapidly to rainfall. The rainfall at Crescent City and
the water level in well 926-131-1 in Crescent City is shown by the
graphs in figure 15. Well 926-131-1 is 200 feet from Lake Stella which is
hydraulically connected to the aquifer. The water level in the well
responds immediately to any change in lake stage caused by rainfall.
-J
, 33.0
L 325
0 Well 926-131-1 in Crescent City
cO320

, 31.5


0 31.0 K T
-1

g 29.5t

RAINFALL AT CRESCENT CITY
S30

'- 25-------- --------- ----__ --- -----
z
2.5
20
15

a S


S............ ......... J....... ..... ...
January February March April May June


1957
Figure 15. Graphs showing the relation between the water level in
in Crescent City and the rainfall in Crescent City.


well 926-131-1


The hydrograph of well 926-131-1 shows several rises in water level
that are not accompanied by a recorded rainfall, and this difference is
due to different amounts of rainfall at the lake and the weather station.
In the Crescent City area water in the aquifer is discharged through
springs into Crescent Lake, which would account in part for the rapid
decline of water level in well 926-131-1 after the rainfall ceases.
The average yearly water level of well 939-138-1, in Palatka, and
the cumulative departure from the average annual precipitation in
Palatka are shown in figure 16. This figure indicates that years of rela-








REPORT OF INVESTIGATIONS NO. 32


SAverage yearly water
> level in well 939-138-1
W in Palatka I
- i3 \ -------~---------------

o-- --I _


-----------------N--------------------------- ^_---- __
Ui















Cumulative departure from
overage precipitation
40-- in Polatko


30
0 20
$ 31-----------------------------------------\------














,o
-0


















avigure 16. raph showing the relation between the water level in wetill 99-18-1
in Palatka and the rainfall in Palatka.



tively high average water levels in 939-138-1 correspond with years
of relatively high precipitation and vice versa. Figure 17 shows hydro-
graphs of wells 925-188-1 and 989-188-1. Well 925-188-1 is in an area
3 0 -- --- -- I- --- -- -
,03Q--------------------^--------------------^------ -



























where an insignificant amount of water is pumped by wells and the
average yearly water level declined about 2.5 feet during 1958-57, a
Figure 16. Graph showing the relation between the water level in well 939-138-1
in Palatka and the rainfall in Palatka.







FLORIDA GEOLOGICAL SURVEY


period of deficient rainfall. Well 989-188-1 is in an area where a large
volume of water is pumped for crop irrigation and industry, and the
average yearly water level declined about 5 feet during the same
period. Thus, the effect of pumpage has the same effect as changes in
rainfall on the water levels and it was not possible to separate the effect
of either.





__"i l l __- -_+__t
WELL 925 (38-1.
4 -Ies southeast of Weako


Figure 17. Hydrographs showing the seasonal fluctuations and the progressive trends
of the artesian heads in wells 939-138-1, and 925-138-1, in Putnam County.

Fluctuations caused by pumping: The fluctuation of water levels
due to the withdrawal of water by wells was noted in most of the ob-
servation wells in the area. The largest water-level fluctuations were
observed in areas where water was pumped for crop irrigation. The hy-
drograph of the water level in well 947-126-1, near the center of the Elk-
ton farming community, is shown in figure 18 for the period 1956-58. The
water level in this well declined as much as 11 feet during the potato
growing season in March 1956 and February 1957 and recovered rapidly
at the end of the season during 1956-57. Rainfall was above average
during the potato growing season of 1958; consequently, the amount of
water pumped for irrigation was small and the resultant water-level
decline was relatively small.








REPORT OF INVESTIGATIONS No. 32


WELL 947-126-1
7
8 7 ---, _____-_

10

12 ___
13
43 -- --- __-__---- --- -- ___ __ ___ __ ___
15 Note: Broken line indicates
15 missing record.
161956
7
18--

20
S21








4 I
10 ---








w 20 -- I -- -
w21 --I--I----I----I---I---- ---- ---- ----___I_____ __I







m1957


19 -- -"--- --- -- -, float hanging


JAN FEB MAR APR MAY JUNE I JULY AUG SEPT OCT NOV I DEC
1958
Figure 18. Hydrographs of well 947-126-1 in St. Johns County.


The hydrograph of well 947-126-1 in figure 19 shows the combined
effect on the water levels in this well of six wells pumping a total of
approximately 2,000 gpm (gallons per minute) within a 1-mile radius.
These wells supplied water to potato washing and grading units that
operated 6 days a week, being inoperative from Saturday afternoon
until Monday morning. During the week days the water level declined
each day during pumping and recovered partially each night when the
wells shut off. On the weekends when the wells were not used the
water level recovered almost completely.

Fluctuations caused by earthquakes: Earthquake waves passing
through the earth cause the artesian aquifer to expand and contract
and are evidenced by the rapid rise and fall of water levels in wells.
W 2 ---- --- --- -- --- --






Fiur 1820rgahso el97-2- nS. on on

























and are evidenced by the rapid rise and fall'-of water levels in wells.








56 FLORIDA GEOLOGICAL SURVEY

10.0
A A A A A Maximum Afluctualion L7 ft.

9oII I I AI I A-- A- t


80 d
Predicted high ocean tides...
24 25 26 27 28 29 30
> JANUARY 1956
WELL 945-115-1 at Crescent Beach


z 3275
< Maximum fluctuation 0.30 ft --
S32-50 -

3225 Northern Japan earthquake
S3200 --8
3 4 5 6 7 8 9
NOVEMBER 1958
^ WELL 949-123-1, 6 miles southeast of St. Augustine



30 ---


S29


28-----


day Sunday Sunday
18 2 19 20 21 22 23 24 25 26 27 28 29 30 31 I 2
MAY 1958 JUNE
WELL 947-126-1, at Elkton
Figure 19. Hydrographs showing the effect of ground-water pumpage, earthquakes,
and ocean tides on the water levels.


The effect of earthquake waves was recorded on the wells in the area that
were equipped with water-level recorders. These fluctuations were ob-
served and recorded in six wells in the area. The effect of a very intense
earthquake in northern Japan on November 7, 1958, on the water level
in well 949-123-1 is shown in figure 25. This earthquake caused the
water levels to fluctuate for over an hour and attain a maximum fluc-
tuation of 0.30 foot.

Fluctuations caused by ocean tides: The water level in many artesian
wells near the Atlantic Ocean fluctuates in response to ocean tides.







REPORT OF INVESTIGATIONS No. 82


These fluctuations are due to one or two causes: (1) direct transfer of
water between the ocean and the aquifer, and (2) by compression
and expansion of the aquifer during a rising tide and falling tide.
In areas where the aquifer outcrops under the ocean or submarine
springs occur near the coast, water levels in wells near the coast fluc-
tute with the tidal movements. As the tide rises there is an increase of
ocean-water head on the submarine springs and outcrops, which may
reduce or stop the discharge from the aquifer and possibly reverse
the flow. The reduction in discharge during the tidal high allows the
aquifer to recover. The reverse conditions occur as the tide falls and
the discharge increases.
Where the aquifer is not hydrologically connected with the ocean or
where the aquifer is exposed to the ocean only at places more or less
remote from the well, the water levels change as the load on the aquifer
varies. The increased weight on the aquifer during a rising tide com-
presses the aquifer and the water therein and the artesian pressure
increases. The reverse situation prevails as the tide falls and the arte-
sian pressure decreases.
Cyclic fluctuation resulting from ocean tides was observed in wells
near the ocean in eastern St. Johns and eastern Flagler counties. Well
945-115-1 at Crescent Beach, 2.2 miles west of a large submarine spring,
was equipped with a water-level recorder during the last 2 weeks in
January 1956. As shown in figure 19 the water level in the well fluc-
tuated very closely in time sequence with the predicted high ocean
tides. This well is also affected by changes in atmospheric pressures
which combine with the tidal effect to cause the amplitude of the oscil-
lation to vary from 1.0 to 1.7 feet. The average fluctuation during this
period was 1.37 feet which would probably be the net tidal effect as the
atmospheric pressure was relatively constant during the 2-week period.
The average amplitude of the water-level fluctuations in this well was
about one-fourth the ocean-tide fluctuation which was nearly 6 feet.
Fluctuations caused by changes in atmospheric pressure: Atmos-
pheric pressure changes cause corresponding changes in the water level
of artesian wells (Parker and Stringfield, 1950, p. 450-458). Water-
level fluctuations in artesian wells that are caused by small daily
changes in atmospheric pressure are generally masked or damped by
greater fluctuations resulting from other causes.
Large daily fluctuations of water levels occur when the high ocean
tides coincide with atmospheric lows. When a high ocean tide coincides
with an atmospheric high or vice versa the water-level fluctuations are
very small. The water-level fluctuations in well 949-123-1 and the








FLORIDA GEOLOGICAL SURVEY


atmospheric pressure, in feet of water, at the U.S. Weather Bureau
Station, WFOY, Ponce de Leon Broadcasting Co., Inc., St. Augustine,
are shown in figure 20. During February 1958 several low-pressure air
masses moved through the area, and the water levels fluctuated in
response to the changes in air pressure. The periods of low atmospheric
pressure on February 7 and 15 caused high water levels at these times in
well 949-128-1.


"T '.---


I I I
Water level in well 949-123-1/ I __

32.5---
320
33.2

3 Barometric pressure at St. Augustine
336

340
342
34.4
6 7 8 9 10 1I 12 13 14 15 16
February 1958


Figure 20. Effect of atmospheric pressure on the water levels in well 949-123-1,
6 miles southeast of St. Augustine.


Piezometric surface: The piezometric surface is an imaginary surface
to which water from an aquifer will rise in tightly cased wells that
penetrate the aquifer. The piezometric surface is generally represented
on a map by contour lines that connect points of equal altitude. The
configuration of the lines shows the direction of water movement, which
is perpendicular and downgradient and also areas of recharge and dis-
charge which are at piezometric highs and lows, respectively.

The piezometric surface of the Florida Peninsula is shown by contour
lines in figure 21; these lines represent approximately the height, in feet
above mean sea level, to which water will rise in tightly cased wells
that penetrate the Floridan aquifer. The contours show a dome in cen-
tral Polk County, which indicates that considerable water enters the
artesian aquifer in Polk and surrounding counties (Stringfield, 1936, p.
148). The water moves downgradient from this area, in a direction
approximately perpendicular to the contours.

Piezometric maps of the Floridan aquifer in Flagler, Putnam, and
St Johns counties are shown by figures 22, 28, and 24. Each map was
drawn from approximately 200 control wells. The three maps were con-
structed to show the changes in the piezometric surface that result from


'I :
-2
c
; 44


*
I
o



1 1











REPORT OF INVESTIGATIONS No. 32


EXPLANATION
Conour represents the ght, i feel referred to meon sea level.
to which woler would" hove risen in tightly cased wels that
penetrate lhe maolr water-bearing formolaons in the Floridon
oquifer, July 6-17, 1961
Contor ntervol 20 feet













. -. 0
c-zx J .


4,


7 N

a5



o


Bose taken from 1933 editon of mop of
Florida bj U.S. Geological Survey

Figure 21. Peninsula of Florida, showing the piezometric surface of the Floridan

aquifer.


0 0 2D 30 40 50 m..:s








FLORIDA GEOLOGICAL SURVEY


seasonal and annual recharge and discharge of the aquifer. In general,
the configuration of the piezometric surface remains relatively constant
but large depression cones are developed in the farming areas during


Figure 22. Flagler,


_5 2 -O__ m
4w ,,' o no' y- n o is" B 1' as" br03'

Putnam, and St. Johns counties showing the piezometric surface
in April 1956.


the irrigation seasons. In each of the three maps the piezometric surface
slopes gently from recharge areas in the north-central part of the State,
including northwestern Putnam County, toward the south and east.
The lows in the piezometric surface near the junction of the Oklawaha
and St. Johns rivers in Putnam County, in the Haw Creek Basin in
Flagler County, and in the area from Crescent Beach to Flagler Beach


WS &TY-.1







REPORT OF INVESTIGATIONS NO. 32


are the result of natural discharge. The discharge at the Oklawaha-St.
Johns River junction is probably caused by the breaching of the aqui-
clude by the river channels or a fault, or a combination of both (fig. 8,


P ,I o 45 '' I I" I o-

Figure 28. Flagler, Putnam, and St. Johns counties showing the piezometric surface
in September 1956.

9). The discharge in the Haw Creek Basin is caused by upward
leakage of water through the thin aquiclude and by springs that breach
the aquiclude. Water is discharged where the aquifer outcrops in the
ocean floor and where breaches in the aquiclude have resulted in sub-
marine springs near the shoreline. The piezometric surface along the
coast slopes toward the southeast and is about 10 to 20 feet above sea










62 FLORIDA GEOLOGICAL SURVEY



level. Seaward from the coast the piezometric surface appears to con-

tinue to slope gently toward the southeast and intersects sea level a

few miles to the east. A submarine spring about 2M miles east of Cres-

cent Beach has been described by Stringfield and Cooper (1951).


Figure 24. Flagler,


L- .. ... .........; .- -/.)

W us o 3w Vs to at a o aro


Putnam, and St. Johns counties showing the piezometric surface
in September 1958.


A conspicuous high in the piezometric surface that indicates local

recharge is in the hilly upland area between Crescent Lake and the St.

Johns River. In this area water enters the aquifer through sinkholes

which have breached the aquiclude and flows principally to the east

and west. Local recharge also occurs in the central part of St. Johns


Woo' 3' 40o' 3' 30'


.37
Well. number is altitude of the
piezometric surface in September
1958
rO ----
Contour showing the altitude of
the piezometrc surface in feet
Dashed where inferred.
Note Contour interval, 5 feet east
of the St. Johns River.
10 feet west of the St
Johns River.


i1
I
19

t=/
a r

ia
; jd
r:i
-P! Y;
~I
r(r
i x-
r-

s
c






t







REPORT OF INVESTIGATIONS No. 32


County north of Elkton where the piezometric surface is high. This area
is topographically high, contains numerous highland swamps and lakes,
and the water table is considerably higher than the piezometric surface.
The map of the piezometric 'surface in figure 22 was prepared from
water-level measurements made in, April 1956 which was a period of
extremely low water levels. The low condition was preceded by a 3-
year drought that had a 16-inch average deficiency in rainfall. Many
new irrigation wells were installed and old wells were used more fre-
quently during this period of dry weather, thus greatly increasing the
ground-water pumpage over that of previous years. These effects
caused the piezometric surface in the area to decline about 4 feet during
this 3-year period and a depression cone to develop near the intersection
of the three counties in the Haw Creek Basin.
The contours on the piezometric surface in figure 23 were con-
structed from September 1956 water-level measurements, when ground-
water pumpage was at a minimum. A comparison of the contours in
figures 22 and 23 shows that by September the depression cones caused
by pumping in the farming areas had disappeared and the piezometric
surface had recovered about 1.5 feet over most of the project area and
10 to 20 feet in the farming areas.
The map of the piezometric surface in figure 24 was constructed
from September 1958 water-level measurements and shows the effect
of the preceding 2 years of average rainfall and reduced ground-water
pumping. A comparison of figures 23 and 24 shows that during this
period the piezometric surface rose about 1.2 feet over most of the proj-
ect area and about 2 feet in the recharge area of northwestern Putnam
County. Subsequent periodic water-level measurements on key wells in
the recharge area show that the piezometric surface continued to rise
through 1958. A study of past records indicates the piezometric surface
will rise several more feet if rainfall is normal in the future.
Area of artesian flow: Artesian wells will flow in areas where the
piezometric surface stands higher than the land surface. Figure 25 shows
the small area of flow that occurred in April 1956 when artesian pres-
sures were extremely low and the larger area of flow in September 1958
when the artesian pressures were higher. The shaded intermediate area
represents the areas where water flowed intermittently during the inter-
vening time.
The area of artesian flow covers the narrow strip of lowlands which
border the coast in Flagler and southern St. Johns counties, south of St.
Augustine. North of St. Augustine, the area of artesian flow extends
completely across northern St. Johns County. In the St. Johns River







FLORIDA GEOLOGICAL SURVEY


valley and its tributaries, the area of flow extends southward from north
em St. Johns County becoming narrower on the east side of the river a:;
the artesian pressure diminishes. North of the Oklawaha River and or
the west side of the St. Johns River the area of artesian flow broadens
and extends westward toward the hilly uplands in west-central Putnam
County. South of the Oklawaha River and on the west side of the St.
Johns River the area of flow includes only the river area and the low
river-swamp areas.
The most prominent area of intermittent flow is east of the St. Johns
River in Flagler, east-central Putnam, and southern St. Johns counties.
This area includes most of the farming area where the piezometric sur-
face is about the same altitude as the relatively flat land surface. A
slight seasonal decline in the altitude of the piezometric surface can
reduce the area of flow by several miles.
The area of flow in the three counties has decreased in the past few
years. A map by Stringfield (1936, pl. 10) shows only one small non-
flowing area east of the St. Johns River, Dunns Creek, Crescent Lake,
and the west Flagler-Volusia County boundary. This small nonflowing
area (approximately 80 square miles) lies within the area bounded by
State Highways 5, 13, and 208. Older records and old flowing-well loca-
tions dating back to about 1900 indicate that the land described herein-
above, excepting Durbin Hill in northern St. Johns County, was pre-
viously an area of artesian flow.
Areas of artesian flow in Putnam County not described above have
not changed appreciably during the past 60 years, owing to the great
relief of the land surface at the line of intersection with the piezometric
surface. Figure 25 shows no perceptible change in the areas of flow in
western Putnam County between 1956-58 when water levels rose an
average of approximately 2 feet in the area. An exception to this is the
two outlying nonflowing areas north of the Oklawaha-St. Johns River
intersection which are topographically low and are only slightly higher
than the piezometric surface. These two areas were an area of artesian
flow on the map by Stringfield (1936, pl. 10).
The area of flow will continue to change with the fluctuation of the
piezometric surface. The greatest changes will continue to occur in the
gently sloping farming areas where there are large water-level fluctua-
tions due to ground-water pumping.
Water-bearing characteristics: The water-bearing characteristics of
the Floridan aquifer system were determined by collecting aquifer data
and analyzing it by various methods.








REPORT OF INVESTIGATIONS No. 32


The drawdown data from pumping tests were analyzed by com-
paring the resulting curves with a family of leaky-aquifer type curves
developedd by H. H. Cooper, Jr., of the U.S. Geological Survey to deter-
mine the coefficient of leakance, transmissibility, and storage. The
family of type curves is based upon the equation for nonsteady flow in
an infinite leaky aquifer developed by Hantush and Jacob (1955, p.
95-100) and described by Hantush (1956, p. 702-714). The equations
assume a permeable aquifer overlain by semipermeable beds through
which water, under a constant head, can infiltrate to recharge the
aquifer. The coefficient of leakance is defined as the number of gallons
that will pass through each cubic foot of semipermeable confining bed
in one day under a unit hydraulic gradient. It is equal to the vertical
permeability of the confining bed in Meinzer units divided by the bed
thickness.

The recovery data from pumping tests were analyzed by the method
of Theis (1935) to determine only the coefficient of transmissibility. An
approximation of the coefficient of leakance was determined by a
geometric analysis of the piezometric surface (fig. 26, 27). This was
possible by assuming steady-state flow conditions and by using a coef-
ficient of transmissibility which was obtained from the pumping-test
data. In this analysis the water table was assumed to be 2 feet below
and parallel to the land surface. The water-table contours were gener-
alized to conform to the land surface. In these figures the equations


Figure 26. Geometric analysis of the piezometric surface near Spuds to determine
the coefficient of leakance.


A B ah= C
250- I2 ftlmile I= 0.26 ft/mile






L=13,700ft- PRINCIPAL ARTESIAN AQUIFER
200- Oa "Ob T= 280,000 gal/day/ft.

0=TIw
25 2800001026 2









a= 5"" = 106 gal/day
S=106-13=93 gal/day


EXPLANATION
Contour on the ezomethc surface(MSLdatum)
W 4b c 5280







S20.0-- -Geerad contour onthe water tole(MSLd

7W -L13.700ft.-7 PRINfIPAL bondayIFER
20.0- ,o -Ob T=280,000 gol/day/ft.

O=Tlw
C2800002
.QI106-15=93 gol/doy
^'*S _(&= 93 =2-83x1073 q./d-y/ft
EXPLANATION

'Aquiferife boundary









66 FLORIDA GEOLOGICAL SURVEY


EXPLANATION
--- Contour on piezometric surface. (M S L datum) 20 A A'
------ Generlized contour line on the water table (M S L dohtum) Piezometric elev 17.5 ft
Bounding streamline ; Water-table elev. 17.5 iftJ
S--Average pirometric
11.9 General land-surface altitude at well location deviation............. 14.3
Well .,-c 15 / --- Averoge water-table
te-. 1 rPiezomerin c elev deviation.......... 014.0
e t Z InGeneral Iand-sturace nnd
W. t.0 water-tables gr1adient ZOOft/mile
i. 10 Piezometric-surface gradient


0 A Leakage area
11-9
12-5 15.8 O= 0-0'
S .. CODYS CORNER 2 80.000xooo Lx8x2.600
15 O =i.24x 106 gal/doy
2 2
ITS 75 919-11-2 A\ Al(9.300 9.300)i
A = 243.100 f12
( 20
m AIA
P 1.24 106
m' 0.3x2.43.10"
P, L7 x 102 gal/day/ft3

Figure 27. Geometric analysis of the piezometric surface near Cody's Corner to
determine the coefficient of leakance.


used express Darcy's law of laminar flow in which Q is the rate of flow
in gallons per day, W is the width of flow in feet, I is the hydraulic
gradient in dimensionless units, and A is the cross sectional area through
which the leakage water percolates. T is the coefficient of transmissi-
bility in gpd/ft and P'/m' is the coefficient of leakance in gpd/ft3.

Pertinent test data are summarized in table 5 and the water-bearing
characteristics listed in the table, for pumped and observed wells
which are similar depth, are plotted in figure 28.

Table 5 and figure 28 show that generally the first 50 to 200 feet of
Eocene limestone are much more permeable than the underlying 200
to 300 feet. Geologic sections (fig. 6) show that the more permeable
zones are the formations of the Ocala Group and the upper part of the
Avon Park Limestone. The conclusion that the Ocala Group has higher.
water-bearing properties than the lower part of the Avon Park Lime-
stone is in agreement in general with Heath and Barraclough (1954,
fig. 2, 8) and Vernon (1951, pl. 2) which shows that in Seminole
County the wells tapping the Ocala Group in the area west of
Lake Monroe have higher specific capacities than wells in the area
south of Lake Monroe which draw exclusively from the Avon Park
Limestone.










TABLE 5. Summary of Pertinent Data and Results of Pumping Tests


Fumped wells Observation wells Thickness of
Depth Eocene Limestone
Dis- ti tap penetration Pump-
Reported depths Reported depths tance of Dis- ng Trans- Storage Leakance
Area (feet) (feet) between Eocene charge dura- visibility coefficient coeficient
Well Well wells Lime- Obser- rate(Q) tion (m) (dimension- ('/m')
number number (feet) stone Pumped vati-n (gal/min) (days) (gal/day/ft) less) (gal/day/ft)
(feet) well well
Casing Total Casing Total (feet) (feet)


Spuds...............
Spuds ...............
West of Bunnell., '..,
West of Bunnell......
Near Codys Corner,,,.
Near Codys Corner...
Near Codys Corner.,,,
N.W. Palatka .......
EastPalatka .........
Eat Palatka.........
East Palatka.........


047-120-7
047-120-2
028-122-3
028-122-0
019-120-2
018-118-3
018-118-3
043-144-2
040-184-1
030-134-4
040-134-1


147
147
120
160
75
50
00

178
160
113
87


310
500
345
405
175
350
360
504
452
547
452


047-120-5 147
047-120-3 220
027-121-2 180
028-122-11 ........
010-110-3 77
018-118-3 60
013-118-2 00
045-143-2 104
040-133-1 ......
030-134-4 113
040-134-3 150


205
505
300
400
188
350
164
348
155
547
452


1,408
805
2,000
230
1,050
(a)
1,040
4,720
133
(a)
1,300


55 604
205 00
120 280
330 370
88 300
200 345
104 345
108 6,000
25 520
434 150
320 520


0.35
.28
.27
.033
.30
1.85 .
1.85
2.08
.32
.07
.32


173,000
200,000
270,000
280,000
100,COO
275,000
275,000
275,000
275,000
360,000
275,000


1.57 X 10-4
5.0 X 10-4
4.7 X10-4
0.0 X 10-4
1,0 X 10-4
(b)
(b)
0.4 X 10-O
(b)
(b)
(b)


1.5 X10-'
.7
5.2 X 10-'
?
1.75 X 10-2
(b)
(b)
1.75 X 10-3
(b)
(b)
(b)


(a Pumped well used for observation well
(b) Only recovery data used








68 FLORIDA GEOLOGICAL SURVEY

Geologic information obtained during the drilling of test wells in
the area indicates that the limestones of the Ocala Group and the
upper part of the Avon Park Limestone are generally more porous and
contain fewer relatively impermeable zones than the lower Eocene de-
posits. Figures 4 and 5 summarize the test-well data. The current-meter
traverses shown on these figures measure the relative velocity of water
in the wells and the rate of flow can only be approximated because of


200 300
m (tt)


12
I0
a




0 100 200 300 400 s5


600 -
500
400
300 -
200 -

100
0 50 100 150 200 2!
m'(ft)


Figure 28. Graphs showing linear relationships between quantities listed in table 5.


the nonuniformity of the diameter of the uncased bore holes. However,
some estimates of flow rate can be determined when the relative veloc-
ity of the flow is studied in conjunction with other known facts.

Lithologic and electric logs from well 939-134-11, shown on figure 5,
indicate a hard impermeable zone at about 300 feet below land sur-
face. The quantity of water passing this hard zone can be calculated
from the relative-velocity graph on the figure. At the time the current-
meter traverse was made, the well was flowing at 150 gpm. Assuming
that the hard zone at 300 feet below land surface was 6 inches in diam-
eter, the minimum diameter possible in the well, the maximum flow
passing by this hard zone would be about 30 percent. Therefore, at
least 70 percent of the water in the well is produced between 300 feet
below land surface and the bottom of the casing.







REPORT OF INVESTIGATIONS No. 32


Based on pumping-test data, geologic information, and current-
meter data, the principal water-producing zone in this area is the top
50 to 200 feet of the Floridan aquifer. In most cases this includes the
Ocala Group of Puri (1957) and the top few feet of the Avon Park
Limestone (fig. 6).
The process of solution has an important effect upon the water-
bearing characteristics of the Eocene limestones. The removal of ma-
terial, such as carbonate in limestone rocks, by the ground water has
the effect of increasing the porosity of limestone aquifers. The rate of
solution is likely to be highest where flow rates are high and the water
moves short distances from points of recharge to points of discharge.
This is generally true in the St. Johns River valley where the discharge
areas are near the recharge areas and hydraulic gradients are steep.
The average porosity of the upper 400 feet of the Eocene limestone in
this area has been calculated by using equations of Jacob (1940, 1941,
1950). Although the simplifying assumptions made in the derivation
of these equations may not be completely fulfilled by existing field con-
ditions, the resultant calculated porosity should be of value for com-
parative purposes.
Jacob's equation (1950) relating barometric efficiency to the elastic
properties of an artesian aquifer is
1
B.E. =
1+B
eB
where cc is the bulk modulus of compression of the solid skeleton of the
aquifer in psi-1
B is the bulk modulus of the compression of water or 3.3 X 10-6 psi-1
e is the porosity
The average barometric efficiency according to the data shown in figure 29
is about 37 percent.

Thus,
cc/e = 5.6 X 10-6 psi-1
S
The plot of storage coefficient in figure 37 shows to be essentially
m
constant and about 2.4 X 10-6 for the upper 400 feet of the Eocene
imestone. The porosity can then be calculated from the equations given
)y Jacob (1950) showing the relationship between storage coefficient
and the porosity, as








FLORIDA GEOLOGICAL SURVEY


S=roem B+-


where ro is the specific weight of water.

The porosity, therefore, is computed to be about 62 percent and cc is
about 3.5 X 10-' psi-.

Reservoir operation: The artesian reservoir system which includes
the aquiclude is not uniformly continuous geologically nor hydrologi-



8.8 Well 949-123-1
B. E. =.884 x .23 384 o Noon, Oct. 22,1956
8.7 -- to
0. 6AM Oct. 24,1956
8.6 -- c

z 8.5
o
O
2-
o 2 .9 --- r ----.1-----
S B.E.= .884x =.40
n- ?_8 .,,_ Well 947-126-1
3 6 PM. Jon.7, 1958
S2.7 to
6P.M. Jan. 8, 1958
2.6


0 0

S B.E. =.884 x -- .364
- 24-


Well 949-123-1
Noon Feb 25, 1958
to
Noon Feb 27, 1958


% Ba c e y 4 Change in water level, in feet
% Barometric efficiency = 88.4
Change in atmospheric pressure in inches of
i ',- I r-I I mercury


B. E. = .884 x -2 =.315



n o
Sn 0


',,0 1


Well 947-126-1
Noon Feb. 25, 1958
to
Noon Feb. 27, 1958


29.40 29.60. 29.80 30.00 30.20 30.40
ATMOSPHERIC PRESSURE (inches of mercury)

Figure 29. Graphs showing the barometric efficiency of the Floridan aquifer.


0 9.3
LJ
9 9.2
I-
U 9.1
Li

9.0
z
S89
UJ
> 88
-J
26
trl
S2-5

2-4

2.3


1
|


J






REPORT OF INVESTIGATIONS No. 32


Sally throughout the project area. The acquiclude, primarily consisting
of the Hawthorn Formation, is missing in parts of Flagler and Putnam
counties as shown on the geologic section in figure 6 and on the map
in figure 8. The Hawthorn Formation, because of its impermeable
character, is a very effective confining bed and its absence near Bunnell
results in a hydraulic interconnection between the artesian reservoir
and nonartesian aquifer in this area. Discontinuities such as this in the
artesian reservoir system have an important effect on the manner in
which the reservoir operates. For instance, figure 30 shows the relation-
ship between rainfall at Crescent City and the water level in well 927-
115-1 at Bunnell near the area where the principal confining beds are
absent. The figure shows that the above-average rainfall during 1941-
47 did not raise the water level in well 927-115-1 above the levels of
previous years of average rainfall. Geologic conditions and hydraulic
interconnections of the reservoirs tend to impose an upper limit of
ground-water head at an altitude of a few feet less than that of the
general land surface. The water-level graph shows that the artesian wa-
ter level declined during the period of near-normal rainfall during
1947-58. If this is the result of increased pumping from the artesian res-
ervoir during that period there may have been some salvage of otherwise
rejected recharge by the nonartesian reservoir in this area. However, it
may also indicate instead that rainfall at Crescent City is not representa-
tive of rainfall throughout the area.
Wells: Approximately 1,000 wells were inventoried in the project
area during the investigation. The inventory consisted of the collection
of information on the location, depth, length, and diameter of casing,
yield, use, and other pertinent facts on the wells. The location of the
wells is shown by figures 36, 37, and 38 and well information is pub-
lished in Florida Geological Survey Information Circular 37. About 90
percent of the wells inventoried were completed in the Floridan aqui-
fer and 10 percent in other overlying aquifers.
The wells completed in the Floridan aquifer range from 2 to 20 inches
in diameter and from 50 to 1,440 feet in depth. Most domestic, stock, and
swimming-pool wells were generally 4 inches or less in diameter, and the
wells used for irrigation, industry, and public supply were generally 4
inches or more in diameter. The 4-inch diameter well is the most common
well drilled in this area.
Artesian wells constructed in this area are drilled principally by the
'otary and cable-tool methods. The drilling rigs are generally truck-
;nounted and self-propelled. The rotary drilling rigs consist of a draw-
vorks, derrick, mud pump, and two engines; one engine is used to







FLORIDA GEOLOGICAL SURVEY


_J
LLI>

>


L.a Li
L aJ
LUJ



>--
l-0
i <
LJ








0 z
1- U


0<
.J U

Scr


LU




-j
U-J
z



z
Q: <









Sz-I

ll
<- U


Figure 30. Graphs showing the relationship between the rainfall at Crescent City
and the water level in well 927-115-1 at Bunnell.


operate the draw-works and the other is used to operate the mud
pump. The cable-tool rigs consist of a draw-works, derrick, and one
engine to operate the draw-works.

Rotary drilling is accomplished by rotating a fishtail or standard
cone-type rock bit that is screwed to the drill pipe. The drill pipe is
rotated and mud of a sufficient viscosity and weight is circulated from


16 -,- i




WELL 927-115-1, at Bunnell
13 1\ i ,, I I' 1

80

60

40










Crescent City
1 )00

80

o0 -
20 -,^-- - -


7z / ---/Z 0








20
-40 - - -

1200 .. .-- NM0- N






100 -)1-- - -- -





80-----------------------
60 1 101',-- - -
r-o-// ,,r =,/ //r/// / /,--*/''/ -7-

40 o ~ // -- //i/.//_/./ ~ Z y /.--^ =








REPORT OF INVESTIGATIONS No. 32


the mud pit down the inside of the drill pipe and up the well between
the drill pipe and rock formation to the mud pit. The mud removes the
cuttings and plasters the sides of the open hole to prevent caving. The
hole is usually drilled to a depth believed by the driller to be through
the last sand bed he expects to encounter and into the clay near the
top of the artesian aquifer; at this point the driller will install the casing
and drive it a few feet into the undisturbed clay. The driller will com-
plete the well by drilling an open hole through the clay and into the
limestone of the Floridan aquifer.
Cable-tool drilling in this area is accomplished by driving casing into
the unconsolidated material and then drilling and clearing the material
out of the casing. When the well has progressed to the depth where
rock is encountered the well is continued by drilling an open hole
below the casing. The casing may be driven ahead at any time to block
off sand beds that may cave into the well.
Wells completed in the secondary artesian and nonartesian aquifers
range from 1, to 12 inches in diameter and from 10 feet to approximately
300 feet in depth. Most of these wells are equipped with well-point
screens when they are completed in unconsolidated sand but they are
left with open-end casings when completed in shell beds. These wells are
used extensively for rural domestic supplies and for lawn irrigation.
There are a few larger diameter wells that are equipped with well
screens and are gravel-packed. These wells are used by municipalities and
several industrial concerns in this area.

QUALITY OF WATER

Rain falling on the earth is relatively pure except for small amounts
of atmospheric gases and dust. Part of the rain is absorbed into the
earth and begins to percolate downward, dissolving some of the mate-
rial with which it comes in contact. Some minerals are dissolved more
easily than others; thus, the degree of mineralization of ground water
depends generally upon the composition of the material through which
water passes.
The results of chemical analyses of 20 samples of water from wells
in aquifers overlying the Floridan aquifer are shown in table 6. Sixty
samples of water from wells in the Floridan aquifer and one sample of
water from the ocean in the vicinity of Miami are shown in table 7.
The values for each ion are shown in the tables in parts per million.
One ppm is equal to about 1 ounce of constituents in 7,500 gallons of
water.







FLORIDA GEOLOGICAL SURVEY


NONARTESIAN AND SECONDARY ARTESIAN AQUIFERS
The quality of water from wells in the nonartesian and secondary
artesian aquifers is dependent upon local geologic and hydrologic con-
ditions. Therefore, the quality of water from wells in these aquifers may
vary greatly within relatively short distances (table 6).
The nonartesian aquifer is recharged directly by local rainfall and
the quality of water from wells in the aquifers will differ depending
upon the minerals and organic materials that are found in the imme-
diate vicinity of the wells. The quality of water is affected also by mix-
ing with water from nearby rivers, lakes, or the ocean and by water
from the Floridan aquifer which may enter the nonartesian aquifer by
upward leakage through the aquiclude and by downward percolation
of artesian water that has been used for irrigation.
Water in the secondary artesian aquifers is derived locally either by
upward leakage from the underlying Floridan aquifer -or by downward
percolation from the overlying nonartesian aquifer. Therefore, the qual-
ity of the water in the secondary artesian aquifers will be similar to the
quality of the water in either one or the other aquifer within the same
general area. In the deeper secondary artesian aquifers the quality of
water usually is similar to water in the underlying Floridan aquifer,
and in the shallower secondary artesian aquifers the quality of water
usually is similar to water in the overlying or nearby nonartesian
aquifer.

FLORIDAN AQUIFER
The amount and the composition of dissolved minerals in water
from the Floridan aquifer depend upon the chemical composition and
physical structure of the rocks with which the water comes in contact
and upon the amount of contamination with sea water. In recharge
areas, where rain water first enters the aquifer the water is only slightly
mineralized. As the water moves through the soft, porous limestones
(CaCO3) and dolomites [(Ca,Mg) COs] it dissolves mineral matter
from the rocks through which it flows and mixes with mineralized wa-
ter already in the rocks.
As shown in table 7, the degree of mineralization of artesian water,
expressed by the dissolved-solids content, differs widely throughout the
area. In general, however, except for wells contaminated by sea water,
the water from wells in and near the recharge areas is the least min-
eralized and water from wells at the greatest distance from the re-
charge area and at the greatest depth is the most highly mineralized.
The analyses of water from the Floridan aquifer in Flagler, Putnam,







REPORT OF INVESTIGATIONS NO. 32


and St. Johns counties are given in table 7. (See fig. 36, 37, and 88 for
maps showing location of wells.)
Temperature of water in the upper part of the Floridan aquifer gen-
erally ranges from 72 to 750F, which is about 1 to 30F higher than
mean air temperature in this area. Normally the geothermal gradient is
about 1F per 50-75 feet of depth, and the temperature of ground water
increases at approximately the same rate.
Temperature anomalies were recorded in the Tocoi and Crescent
Beach areas but artesian water in both areas is highly mineralized and
is rising from depths where temperatures would normally be higher.
Artesian water is quite often used to moderate the air temperature to
prevent the freezing of young potato plants. Several homes have installed
a series of pipes in the floor and circulate artesian water through them
for heating and cooling.
Silica (Si02) content of artesian water ranges from 4 to 37 ppm and
contributes to the forming of boiler scale in steam production.
Iron (Fe) is one of the most undesirable elements found in water,
because of the taste it imparts and the staining effect it has on clothes,
bathroom fixtures, and exterior painted walls and natural stone struc-
tures. Water from the Floridan aquifer in this area contains very small
amounts of dissolved iron and does little damage except for the per-
manent discoloration of exterior walls and tombstones. Hundreds of
tombstones have been discolored by artesian water, and its use in several
cemeteries has been abandoned. Iron generally can be removed from
water by aeration or chlorination followed by filtration.
Calcium (Ca) and magnesium (Mg) are usually present in relatively
large quantities in water from aquifers that are composed chiefly of
limestone and dolomite minerals. These minerals are readily dissolved
by water containing carbon dioxide, and they furnish calcium and mag-
nesium ions, which are the principal causes of hardness in water. The
calcium content of the water from the Floridan aquifer in the area
ranges from 0 to 401 ppm and magnesium ranges from 5.4 to 459 ppm.
Sodium (Na) and potassium (K) are dissolved in small amounts from
many types of rocks, and they constitute only a small to moderate part
of the total dissolved solids of fresh ground water. However, the sodium
content of water that has been contaminated with sea water is generally
high because sea water is primarily a solution of sodium chloride.
The combined sodium plus potassium content of water from the
Floridan aquifer in the area is in the general range from 5 to 4,000 ppm.











TABLE 0, Analyses of Water from the Aqulfers Overlying the Floridan Aquifer in Flugler, Putnam, and St. Johns Countles, Florida
(Results in part. per million, except specific conductance, pi1, and color)
Formation: Ax, Anastaia (Plelatooens); MP, Late Miocene or Pliocene; II, Hawthorn Analysis by: 1, U.S. Geological Survey, Orals, Fla., and Washington, DC;
Aquifer: N nonartsian; 8, secondary artelan 2. Black Laboratories Inoc, alneaville, Fla.,
Dissolved Solld: a. Temperature of evaporation process unknown; 3. Florida State Board of Health, Jacksonville, Fla
b. Temperature of evaporation process 1005C, 4. Southern Analytical laboratory, Jacksonville, Fla.;
5. Eugene Brown, Chemistry Department, University of Florida, Gainesville, Fla.;
6. U.S. Navy, District Public Works Officer, oth Naval District, Charleston, 8. C.

DiIs Hardness
So. solved Spe
Denth dium solids cflo
Deth of For. Total Cal. Mag. (Na) (reel- con.
Well Owner o cas. Date ma- Aqui. Silica iron clum ne- and Bl- Car- Sul. Chio. Flu. NI. due duct- Anal-
well ing sampled tion fer (81iO) (Fe) (Ca) slum Potas- car- bonate fate ride oride trate on ance pH Color ysls Remarks
(feet) (feet) (Mg) slum bonate (CO) (804) (CI) (F) (NOa) evap- As Non. (mi. by
(K) (HCO) or-. CaCOs car. orom-
tion bonate hoe
at at
180C) 25C)

928-108-6 Town of Flaler
Beach......... 26 2 3-31-52 Ax N. ...... 0.0 92 8 ...... 207 ..... 0.0 160 ...... ...... b535 24 ...... ...... 7.6 5 3
-x do......... 26 26 10-24-52 Ax N ...... .17 87 2 ...... 241 ...... .0 70 0,0 ...... b380 220 28 ..... 7.0 5 3 Raw water
collected at
pumps, 82
wells
-x do.......... 26 26 5-14-87 Ax N ...... 1.3 104 12 .... 158 ..... 46 258 .15 ..... b780 308 150 ...... 6.0 6 5 3 82 wells
treated (Hy.
poohlorina-
tieo) colloct-
ed at plant
outlet
928-111-2 USGSO........... 113 106 7-20-58 H 8 ....... ..... 166 00 ...... 298 0 130 710 .................. 60...... 2,700 7.0 ...... 1
928-114-1 TownofBunnell... 87 87 10-30-34 MP N 17 .00 118 4.6 0.8 390 ...... .4 10 ............ a300 313 .................... 6
1-27-42 2.2 105 5.6 23 3 1 ...... ...... 25 ..... ...... a377 286 .. ...... 7.1 ...... 8
8-23-51 1.5 110 7 ...... 371 ...... .0 31 ........... b395 304 ....... ..... 0.9 3
'929-108-1 Lehigh Portland
Cement Co., Inc.. 00 90 10-30-52 MP N ...... .5 75 .5 ...... 203 ...... .0 05 ...... ...... b400 208 ...... ..... 7.5 5 3
830-130-1 USGS............ 168 164 8- 7-58 H S ....... ...... 68 20 .... 6. 117 0 8 210 ........ ... ... 290 ...... 058 7.5 ...... 1








988-116-1
2, Ravine
G: arden,

094-118-3



952-120-2
i : -2





: -4


931-140


do,...........

City of Palatka...

Marine Studios, Inc.

USGS8...........
City of St. Augue-
tine ............

do...........

do,.. ........
do. W........


L. M. White.......


136

42

18-
20
175

80

89

80
20


Spring


135




18

144

89

89

80
17


8-27-58

5-13-39
4-23-51
5-16-40

9- 5-58

10-20-44
19-31-44
2- 7-51

10-81-44
10-31-44


S

N

S

S



S

N


7.0
18








15


- ~ ' '


8-21-54


.04

2.0






1,4


2

33
31
144

222




202


i


.36

2.0
18
3.0

128




1.0


0.4
.0
103






.0


190

111
120
415

158


304
371

488
414


--


1.8


20






0




......



......


0.3 60

5.2 10
10
.0 180

591 1,160

170 30
120 20
71 39

56 6
130 14


.0


.0






.40
.20



.3
.2


130

b732




372

8644



.,.....


6

96
96
373

1,080

435
412
508

412
435


36 I .2


33










,,..,..


14.5


I I I I I I I


862






4,600


9.2


8.3
7.1

7.5




7.2



.,,,..


70




40
45



20
30


1

4

3 Temperature
70F



1 Wells
1 '
2 Well 8


1 i .



4 Collected at
spring mouth









,


'' '''''''''













TABLE 7. Analyses of Water from the Floridan Aquifer In Flagler, Putnam, and St. Johns Countles, Florida

(Results in parts per million, except specific conductance, plH, and color)
Formation: A Avon Park; IInglis; 0, Ocala roup, where formation is unknown; Analysis by: 1. U.S, Geological Survey, Ocala, Fla. and Washington, D, 0.;
'W, Williston; X, Crystal River; L, Lake City. 2. Black Laboratories, Ino. Gainesville, a.;
Dilolved Bolids: a. Temperature used in evaporation process unknown; 3, Florida State Board of health, Jcksonville, Fla.;
b. Temperature used in evaporation process 105C, 4. Southern Analytical Laboratory, Jao'sonville, Fla.;
6. Eugene Brown, Chemistry Dept,, University of Florida, Gaineaville, Fla.

Dissolved Spe.
Iron (Fe) solids Hardness cilio
con-
SMag. Bl- duct.
For- Cal. ne. So- Potas car Car Sul hio- Flu. Ni. ance Anal-
Well Owner Date ma. Silica clum slum dium slum bonate bonate fate ride oride trate (ml- pll Color ysis Remarks
sampled tion (810s) (Ca) (Mg) (Na) (K) (I(COa) (CO) (S04) (Cl) (F) (NO,) J a As Non- rom-. by
Dia. Total CaCOs car- ho
solved bonate at
5FLAGLR COUNTY


FLAOLER COUNTY


i 919-128-2
0920-110-83
: ,020-1.9-6
" 921-115-1
-923-111-1
923-118-58
924-118-1
924-122-2
9i 8-108-2

27-116-1


USGS.....
H. W. Wells
I. W. Wells
USGS......
USGS......
L. Trad....
USGS.....
P. P. Pellicer
Florida Park
Service...
W.E.Kudna


7-15-88
8-10-56
8-13-86
7-14-68
7-23-68
8- 7-50
8-18-58
8- 7-60


125 ..... 10- 7-55
180..... 8- -24


W, I


19
109



17


26


0.01
.00



.09


.00


0.47
.68



.89


.52

.00
.08


8.6 ......
10 010
14 130
11 I .... .
0.2 .
92 1,500
14 .....
24 485


19
4



28


12


316


3.7
140
29
12
2.4
218
310
218



62


30
1,290
290
190
36
3,020
4,210
1,270

530
738


...... ....,.,
0.2 0.8
.3 1.2



.0 .8


.2 .3


.....
...... .0


282
2,470


847
542
5,430
5,381
2,490

1,070


852









b654
1,610


160
809
410
80
325
1,610
1,890
1,140

540
040


12
586
170
70
0
1,390
1,690
072

280
409


381
4,580
1,420
047
053
0,600
12,200
4,570


7.3
....,.


7




6





18

......


Temp.
74?#


, I


I






927-115-2 W. Dunson
027-115-2 Bunnl). 180 8- 7-56 W, I 14 .05 3.4 288 175 1,070 20 184 0 150 2,500 .0 1.5 4,310 ...... 1,440 1,200 7,890 7.5 4 1
927-116-x Potato
Growers
An...... 400 12- 0-3 ..... ..... ......... 113 16 .... ...... 3 ...... 10 139 .2 ..... ..... b08 300 48 ...... 8.0 .. 3 Collecte
from pit.
28-108-2 Lehigh Temp.
Cement 71"F
Co.,Ic... 411 116 11- 1-40 W,I,A 20 ...... .10 182 02 476 221 ...... 73 1,142 ............ 3,206 b2,700 833 655 ...... 7.1 ...... 2
983-110-1 USGS...... 162 134 0-11-58 W, I ...... ............ 242 138 ...... ...... 189 0 501 1,440 ...... ...... 2,10 ...... 1,170 1,020 5,360 7.6 ...... 1
988-120-1 USGS...... 104 117 8-19-68 W ....... ............ 68 17 ........ ..... 260 0 2.1 65 ...... ...... 402 ...... 240 27 512 7.6 ...... 1
933-123-2 Dinner
Island.... 180..... 8-7-56 W 23 .00 1.3 184 71 210 7.0 212 0 310 500 .4 .8 1,410 ...... 751 578 2,230 7.7 13 1

PUTNAM COUNTY

925-130- Crescent
City ..... 130 130 1-10-25 I 11 ...... .08 40 6.8 14 150 ...... 3.4 24 ...... .0 ...... a171 128 5 ...... ...... ..... ....... Two wells
Municipal
S ppy .. .......... 5-12-40 I ............ .08 40 6.E 13 164 ...... .0 20 .0 ...... ...... a 80 127 1 ...... 7.8 ..........
930-140-1 D.W. Tred-
nick930-140-1 2 8-27-56 W 14 .04 .13 327 243 1,060 50 150 0 51 3,840 .1 .0 7,060 ...... 1,820 1,690 12,100 7.5 0 1 1.002gms/
n... *mlat20UC
082-145-2 W.Tilton... 85 ..... 8-28-56 0 12 .00 .15 68 23 80 2.8 138 0 39 169 .2 .6 ...... 482 239 126 836 7.8 3 1
932-152-1 USED..... 189 ..... 8-28-56 ...... 11 .00 .22 20 8.1 3.1 .0 113 0 1.2 5 .0 .1 ...... 109 98 6 19 8.1 2 1
937-153-1 Town of
97-1 nrlahen 303 300 3- 0-35 XorW 4 ...... .02 25 5.9 6.8 111 ...... 3.9 7 ...... .0 ...... 09 88 0 ........ ..... 4
803 300 -23-49 XorW ............... .. 2 7.0 18 110 ...... .0 ...... ............ .... ll 90 2 ..... 8.0 ...... 3 Well1
0 8-138-1 City of Pa- 060 ..... 1- 4-24 ...... 12 ...... .07 62 28 71 140 ...... 02 174 ...... 0 ....... 532 270 155 8.................. 1
atka No.2 ...... 4-23-51 ..... 18 ...... ...... 6 31 93 161.. 52 21 ...... ..... 290 18... 7.8 ...... 5
.. 9-17-52 .................. .0 61 30 ............. 144 ...... .0 205 .2 ...... ...... a682 276 158 ...... 7.0 5 3
938-188-x Florida Fur- r
niture.... 00 ..... 5-26-42 ...... ............ .15 64 23 76 130 ...... 55 176 ............ ..... a562 254 141 ..... 7.3 ..........

93134-11 USGS...... 114 113 -30-56 X ...... ...... ...... 124 0 ..... ..... 128 0 240 440 ........................ 515 410 1,10 7 ...... 1 Baler
201 11 6- 3-56 I ...... ...... ...... 118 2 .... ...... 126 0 238 440 ..... ........... ...... 510 405 1,920 7.6 ..... 1 do.
338 113 6- 5-56 A 18 ...... .01 112 50 215 5.0 127 0 248 430 .4 3.3 1,150 1,270 510 406 1,090 8.0 3 1 do.
387 113 6- 9-56 A ...... .......... 124 60 .. .........1. 128 0 240 630 .... ...................... 515 410 1,920 76 ..... 1 do.










TABaL 7,-(Continued)


Owner


S 40-134-1 Scott &
SHalsted,Inc.

943-144-2 Hudson
Pulp& Pa-
i perCo., Inc
: 43-200-x Sam Jordan
S44-131-2 R.L.Rawson
944-152-1 T. L. Drake

944-157-1 P. D. Wat-
kins ......
947-137-1 R.J.Han-
cock ......


460 113
508 113
547 113

452 87



864 178
112 85
245 100
220 55
..... .....

210 210

350 40


Date
sampled


6-10-58
6-17-56
6-18-56


For-
ma. Silica
tion (SiOs)


8-27-56 X,W,I


S12- 6-55 X,W,1
11- -50 ......
8-27-56 ......
9-20-46 ......
10-15-50 ......

10-15-50 ......

8-28-56 ......


Iron (Fe)
______ Mags- Bi.
Cal- ne- So- Potas car.
cium lium dium slum bonate
Di Total (Ca) (Mg) (Na) (K) (JlCOa)
solved t
solved


0.12 1.3


11 .11
15 .... .
15 ......

10 ......

12 .00


166 116


... 14 6.0
2.7 142 99
.10 30 8.1
.0 30 6,3

10 0 5.4

.56 25 15


9.0



1 .6
7.4
I 5.0
11
9.7


7.4 22

5.9 1.3 140


Car- Sul- Chlo.
bonate fate ride
(COA) (S0) (CI)


0 384
0 473
0 468


0



0


0
o.. .


535



6.5
1.3
595
3.8
,,....


650 ...... ......
850
855 ...... .....
000 ...... ..... .


Flu- Ni-
oride trate
(F) (NO,)


0.6


Dissolved Spe
solids Hardness eaSo
S on.
duet.
ane
(mi.
As Non. crom-
CaO carM- hoe
bonate at
S25C'O)


1,530


.2 .0 ......
.2 ...... ......

.4 .8 1,130
..... .0 ......
...... ... ....

.1 ...... 60

.4 .2 ..


146
a85


a161





142


700 667 2,840 7.7
030 804 3,540 7.6
.,020 048 3,920 7.5

891 786 2,390 7.8



125 7 249 8.1
60 0 ...........
762 696 1,600 7.7
131 0 ...... 7.8
124 0 ..... 7.8

50 4 ...... 7.2

124 9 250 7.7


Anal.
Color yul Remarks
by I


9


4






2


do.


ST. JOHNS COUNTY


37-122-1 USGS ..... 2 2 140 7 1-8 I,A ...... ...... ...... 114 40 ............ 20 0 170 210 ...... ...... ...... ...... 475 2 9 1,410 7.8 ..... Bailer

sample
382 140 7 2-58 A 37 .. .01 9 63 108 6.2 252 0 200 240 .8 2. 878 1,040 498 292 1,460 8.2 4 1 do.
18 140 7- 7-58 L ............ ....13 2 211 0 277 10.......................... 595 422 1,90 8.0 3 1 do.


-------- I-1----------- :------ ---- -- I


do.


j ;'



1^


' i
'

. ".






140 7- 0-88
140 7- 9-68


941-129-3

9 2-130-2
943-130-1
943-130-2




94 6-116-1


9 5-119-8l




954-110-6
964-185-1

955-117-1
966-120-1
: '56-120-2

987-120-1
005-129-1


007-187-1
010-123-2


G.A. & F.R.
Burrell....
A. Lovett...
J.W.Maltby
........ ..
H.Terry
Parker....
C. V. Rob-
shaor....
FloridaPow-
er & Light
Co.......

City of St.
Augustine.

L.R.Daniels
Heirs of
C.H.Arnold
P.J.Manucy
F.E.C.RR.,
St. Johns
County...
G.R.Tarver
Ponce de
Leon Race-
ways, Inc.
W. A. Jones
Lucy M.
Michler...


9-24-23 X,W,I
A


9-24-23


X,W,I
A


602
622

600


8- 0-66
5-25-49
5-25-49
8-30-48

8- 9-66

0-29-44


80


4-23 X 27 ...... .07 103

8-56 X,W 16 .00 .61 228
2-41 X 25 ...... .13 03
. 0 ... .... .. .... ...

5-51 0, ? ........... .04 1CD
8-6 X, W 25 .00 .26 94


0-42 0 24 ...... .18 88
8-56 0 18 .00 .81 38

1-48 0 ...... ...... .0 18


602'-" -'- -


L
L

0,A,L
O,A,L
0,A,L
0,A,L

0

0


16


21


.... 164
.... .. ... 212

.00 .36 354
.0 .0 204
.0 .0 214
.0 .0 164

.0 .28 389

...... .02 130


...... 11 143


...... .48 116


500 I.....


87 ...... ..... 170 0 168 400 .... .. 765 620 2,030 7.6 .... 1
117 ...... 146 0 501 585 ... .. ...... 1,010 891 2,810 7.6 .. 1

250 1,070 20 120 0 850 2,250 1.0 4,870 ...... 1,910 1,810 8,070 7.7 4
84 220 115 ........... 200 ...... ............ ,400 856 761 .... 7.7 ...... 3
84 199 115 ...... ...... 250 ...... .......... al,650 870 786 .... 7.3 ..... 3
107 100 115 ..... ..... 240 .6 ...... ...... a1,62 1 849 755 .. 7.3 ...... 3

459 3,890 119 150 0 1,080 7,000 .6 .0 13,100 ......2,860 2,730 21,200 7.6 3 1

76 321 163 ...... 324 610 1.0 .4 ...... 1,660 637 803 ............ 6 1


87 302 162 ...... 361 635 ...... .0 ...... 1,780 714 482 ...... ............ 1




I
62 69 152 ...... 381 154 ...... .0 ...... 037 844 420 ...... ...... ...... I

57 47 150 ...... ...... 70 ...... .0 ...... 701 491 368 ....... ... ...... 1

107 11 2.6 98 0 830 16 .1 1,260 ...... 1,010 928 1,550 7.7 2 1
65 55 161......29 7..... ...... ...... 732 458 326...... ...... ...... 1



66 ...... ..... 154 ..... 388 61 ...... ..... .... a631 514 377 ...... 7.5 9 2
60 51 3.0 164 0 288 82 1.0 .2 ...... 790 481 346 1,010 7.8 2 1


39 14 163 ...... 240 20 ...... 0 ...... a549 380 247 ...... 7.3 ...... 2
23 8.0 1 2.0 132 0 70 10 .6 .1 ...... 247 189 81 461 7.8 2 1

34 80 268 ...... 133 18 ...... ............ 429 275 0 .. .. 7.3 ... .. 3


do.
do.









Density at
20C:1.008







;ityNo.3,
davenport
'ark


300o .....


240
500

300


10-2

8-
10-2
.. .


.... .. ...1 7-
100 ..... 8-


9-1
8-

8-4


i










TABULY 7,-(Continued)

Dl)i~slved Spe.
Iron (Fe) solide lHardness cilio
con-
__ M- If. duct-
For- C'al- e So. Pota.- car- Car- Sul- Chlo- Flu- Ni- anee Anal.
Well Owner Date mra- Silica ciunm siun diumn slum bonate bonate fate ride oride rate (nmi- po l Color yal Remarks
s l sampled tioni (8iO2) (Ca) (hMg) (Na) (K) (JICOI) (COa) (804) (CI) (F) (NO) A s Non- croi- by
Die- Total CacO l ear- hbo
Sesolved bonate at
Is N 25C)


010-124-2 A.P. Farr.a 405 ..... 8- 4-48 0 ...... ...... 0.0 54 35 53 277 ...... 144 16 ...... ...... ....a. 420 281 52 ...... 7.3 ...... 3
011-121-1 S.M.Butler ..... .... 8- 8-56 0 26 0.00 .40 64 30 10 2.2 166 0 175 23 0.0 0.1 ...... 452 320 184 641 7.8 4 1
014-122-1 Ponte Vedra
Corp...... 600 380 3-17-47 0 ...... ...... .30 56 37 10 174 ..... 132 33 ............ ..... a422 287 140 ...... 7.7 ...... 3
8-10-53 0 ...... ...... .0 00 26 ............. 154 ...... 100 50 ...... ...... ...... 10 272 146 ...... 7.3 ...... 3
Atlantic Ocean, Miami
Bech, 60 ftoff shore a
at41st 8t.......... ..... 5-23-41.. ...... .. ..... 423 1,324 10,70 42 .. ..... 2,750 10,770 ...... ...... 35,800 ..... ......... ....







REPORT OF INVESTIGATIONS No. 32


Bicarbonate (CHOs) is formed from the solution of limestone and
crher carbonate rocks by water containing carbon dioxide. The bicar-
I:onate content of water in the aquifer ranges from 22 to 879 ppm. The
bicarbonate content of water from the Floridan aquifer generally is less
than that of water from the overlying younger beds.
Sulfate (SO4) in ground water may be due to the oxidation of
sulfides or solution of sulfate minerals in the rocks and contamination
by saline water. Sulfate concentrations in the area generally are less
in areas of low chloride where the sea water has been flushed from the
aquifer. In northwestern Putnam County, which is a recharge area,
water in the aquifer has a sulfate concentration that generally is less
than 15 ppm. Well 954-135-1, at Picolata, is in an area where sea water
has been flushed out of the upper part of the aquifer and has water that
contains 830 ppm of sulfate and only 16 ppm of chloride. The high con-
centration of sulfate and low chloride probably is due to a local deposit
of anhydrite or gypsum. In the farming areas and along the coast where
there has been contamination by sea water, the water in the Floridan
aquifer generally has a sulfate concentration of more than 100 ppm.
Numerous wells in the eastern part of the area yield water of a suffi-
ciently high concentration of sulfate to produce a mild laxative effect
on humans.
Chloride (Cl) in small quantities is dissolved from most rocks and
soils and is found in large quantities in ground water that has been
contaminated by sea water. The chloride content of water from the
Floridan aquifer in Flagler, Putnam, and St. Johns counties is in the
general range from 10 to 7,000 ppm (table 7; fig. 32). Water with the
lowest chloride content generally comes from wells closest to the re-
charge areas, and water with the highest chloride content comes from
wells in discharge areas where there has been some salt-water con-
tamination. The chloride content of water generally is a good index of
-he extent of salt-water contamination and is discussed more com-
letely under the section on "Salt-Water Contamination."
Water with a high chloride content is very corrosive to metals,
harmful to most cultivated plants, and unpleasant to drink. A concen-
ration of about 400 to 500 ppm of chloride in water can be tasted
,y most people. The U.S. Public Health Service (1961) suggests a
maximum limit of 250 ppm of chloride for public supplies.
Fluoride (F) occurs in small amounts in almost all artesian-water
imples in the area; 29 samples were analyzed and the fluoride con-
entration ranged from 0.0 to 1.0 ppm. Studies in some areas of the
unitedd States have shown that children who drink water that contains







FLORIDA GEOLOGICAL SURVEY


about 1.0 ppm of fluoride have fewer dental cavities than those who
drink water with much less than 1.0 ppm (Black and Brown, 1951.
p. 15). However, fluoride in excess of 1.5 ppm tends to cause a mottling
of the teeth. Several water samples that were analyzed by the State
Board of Health and the U.S. Geological Survey (table 7) show that
in northeast St. Johns County the water has the optimum concentration
of fluoride (0.5-1.0 ppm), and the remainder of the area is somewhat
deficient in fluoride for good tooth development.


ml a E am E


0) I\ I N 0I


CHLORIDE CONTENT, IN PARTS PER MILLION
Figure 32. Diagram showing the chloride content of water versus depth of well
in an area 3 miles north of Cody's Corner, Flagler County.

Nitrate (NOa) concentrations in the water from the Floridan aqui-
fer in the area ranged from 0 to 3.3 ppm. The analyses indicate that
nitrate is relatively unimportant in the artesian water of the area.
Dissolved-solids content of water is approximately equal to the
amount of mineral matter that remains after a quantity of water is
evaporated. The U.S. Public Health Service drinking water standards
(1961) suggest an upper limit of 500 ppm of dissolved solids in drink-
ing water. Dissolved-solids content of water from the Floridan aquifer
in this area was in the general range from 100 to 13,100 ppm.







REPORT OF INVESTIGATIONS No. 32


Specific conductance of water is a measure of its capacity to con-
uct an electrical current and depends upon the concentration and
onization of the minerals in solution. Table 7 shows that waters with
!he higher chloride content have the greater ability to conduct elec-
tricity; thus, specific conductance is usually a good measure of the chlo-
ride content of water.
Hydrogen-ion concentration of an aqueous solution is represented
by a number which is the negative logarithm of the hydrogen-ion con-
centration in moles per liter. This number is called pH. Water that has
a pH of 7.0 is said to be neutral. Water having a pH of less than 7.0 is
acidic and may be corrosive; water having a pH greater than 7.0 is
alkaline and not generally corrosive. All water samples from the Flor-
idan aquifer (table 7) were slightly alkaline.
Hydrogen sulfide gas is held in solution in some ground water. Upon
exposure to air some of the gas escapes and gives "sulfur water" its
characteristic odor. Analyses were not made of the hydrogen sulfide in
artesian water, but its characteristic odor was noted at most artesian
wells in the area. The gas is undesirable as it has a corrosive effect on
metal plumbing and turns silverware black.
Hardness of water is due principally to the cations, calcium and mag-
nesium. Hardness caused by calcium and magnesium equivalent to the
carbonate and bicarbonate is referred to as carbonate hardness. Hard-
ness in excess of this amount is called noncarbonate hardness. The most
noticeable effects of hardness are the formation of soap curds and the
lack of suds when soap is added to the water.
The carbonate hardness of water from the Floridan aquifer in
Flagler, Putnam, and St. Johns counties is shown in figure 31. In gen-
eral, the carbonate hardness increases from western Putnam County
toward the coast. The carbonate hardness ranged from 50 ppm in water
from well 944-157-1, in western Putnam County, to 2,860 ppm in water
'rom well 946-116-1, near Crescent Beach in St. Johns County.

SALT-WATER CONTAMINATION
Salt-water contamination of the existing fresh-water supply occurs
n both the Floridan and nonartesian aquifers in some discharge areas
a Flagler, eastern Putnam, and St. Johns counties. This contamination
'as been caused by an intrusion of saline water which comes in contact
nd mixes with the relatively fresh ground water. These intrusions
,ave occurred in various ways, depending upon the location and the
;eologic and hydrologic characteristics of the different areas.







FLORIDA GEOLOGICAL SURVEY


NONARTESIAN AND SECONDARY ARTESIAN AQUIFERS
The nonartesian and secondary artesian aquifers have been con-
taminated by: (1) the upward movement of saline water from the
Floridan aquifer; (2) the lateral encroachment of saline water from the
ocean and rivers; and (3) the inundation of the land by sea water
during Pleistocene time and by high tides during hurricanes in Recent
time.
Water from the Floridan aquifer contaminates the shallow aquifers
at several locations. Three miles north of Cody's Corner in Flagler
County, the aquiclude is thin and discontinuous and upward leakage
from the Floridan aquifer has contaminated the nonartesian aquifer.
Figure 32 shows that well 923-118-4 penetrates the nonartesian aquifer
and contains water with a chloride content of 4,420 ppm. Wells 923-
118-1, 2, 3, and 5, penetrate the Floridan aquifer and contain water with
a chloride content of between 2,770 to 3,090 ppm. The higher chloride
content of water in nonartesian wells can be attributed to a small salt
flat that has developed in the immediate vicinity of the well.. The salt
flat has probably been created from the evaporation of ground water
that has reached the surface and not drained off. When it rains, the
salt crystals are dissolved and this salty water percolates downward and
contaminates the nonartesian aquifer.
Water from the Floridan aquifer presently is contaminating the
nonartesian aquifer near the municipal well field at Flagler Beach. The
relatively salty water from wells penetrating the Floridan aquifer flows
into a pond and then recharges the nonartesian reservoir in the area.
A comparison of the 1952 and 1957 analyses of water from the munic-
ipal wells at Flagler Beach (table 6) shows a noticeable increase in the
dissolved-solids content of the water in the well field. If the water in
these wells continues to supply the pond, the nonartesian aquifer prob-
ably will produce water even more similar to the water in the under-
lying Floridan aquifer.
Lateral encroachment of water from the ocean occurs when the
water levels in the nonartesian aquifer are lowered by ground-water
pumpage, or deficient rainfall or a combination of both. The chloride
content of water from several nonartesian wells near the intracoastal
waterway reached a maximum of 1,300 ppm. However, there have been
reports that numerous other shallow wells had to be abandoned because
the water became too salty for most uses.
At present, the nonartesian aquifer in the low-lying coastal areas is
frequently recharged with sea water when high tides inundate the land
as a result of hurricanes. In some parts of the project area the nonarte-







REPORT OF INVESTIGATIONS NO. 82


s in and secondary artesian aquifers probably contain sea water that
entered the aquifers during the Pleistocene Epoch, but these areas are
not differentiated from areas of recent salt-water encroachment.

FLORIDAN AQUIFER
The Floridan aquifer contains saline water in many areas of Florida.
The presence of saline water in the aquifer could result from several
causes; in this area it probably is due to the infiltration of sea water
into the artesian aquifer during the Pleistocene Epoch when the sea
stood above its present level and much of the present land surface was
inundated. After the high seas declined, fresh water entered the aquifer
and began diluting and flushing out the salty water. The salty water has
been completely flushed out of the aquifer in the recharge areas, but in
areas distant from the recharge areas and in deeper zones of the aquifer
the flushing is still incomplete. Flushing of the aquifer will continue as
long as the artesian pressure in the aquifer is relatively high. Lowering
of the artesian pressure retards the flushing and if the artesian pressure
were lowered below sea level, sea water would again enter the aquifer
near the east coast.
Chloride salts constitute about 90 percent of the dissolved solids in
sea water; therefore, the chloride content of ground water is generally a
reliable index of the amount of contamination of sea water. The chloride
content of water samples from 800 wells was determined to define the
amount of aerial and vertical contamination in the aquifer.
Figure 33 shows the chloride content of water from wells that pene-
trate less than 200 feet of the Floridan aquifer. The chloride content of
the water is less than 50 ppm in western and northern Putnam and in
western and northern St. Johns counties, in southeastern Putnam County
between Crescent Lake and the St. Johns River, and in north-central
atnd southern Flagler County. The chloride content of the water is more
blan 1,000 ppm in southeastern St. Johns County, northeastern Flagler
county, and the Haw Creek Basin in Flagler County.
Figure 34 shows the chloride content of water from wells that pene-
rate more than 200 feet of the Floridan aquifer. A comparison of figures
3 and 34 indicates that the lower part of the aquifer has been flushed
*ss completely than the upper part. The 0 to 50 ppm zone is smaller
ild the zone containing more than 1,000 ppm chloride is larger in the
,wer part of the aquifer.
Several wells were sampled at various depths to determine the de-
ree of contamination with depth. Test wells 937-122-1 and 939-134-11







FLORIDA GEOLOGICAL SURVEY


(fig. 4, 5) and well 923-118-5 (fig. 32) were sampled during construction
and each showed a progressive increase in chloride content with depth.
Several other wells were sampled after their completion and with the
exception of wells in the areas northeast of Tocoi and southeast of Durbin
the salinity of water increased with depth.
Several wells in the Tocoi area and one well 3 miles southeast of
Tocoi yield water from the shallower zones that is higher in chloride
content than water from the deeper zones. In this area, water in the
lower zone is fresher than water in the upper zone. This lower zone
yields very little water except during the pumping season when the
upper zone has had a considerable pressure drop. An abnormal situa-
tion then arises of the water in the well becoming fresher with increased
pumping because of more water being produced from the fresher
lower zone. Saltier water in the upper zone probably is due to connate
water migrating upward along a possible joint or fault and bypassing the
deeper, less permeable zone that contains fresh water.
Water was sampled periodically from 50 wells and analyzed for
chloride content to determine the relationship between the chloride
content and the artesian pressure. In areas of high artesian pressure and
small ground-water. discharge there was little or no change in chloride
content and the observed changes were within the magnitude of error
of the analysis. In areas of large ground-water discharge the chloride
content usually fluctuated with the artesian pressure; a decrease in
artesian pressure is accompanied by an increase in the chloride content
and vice versa (fig. 35). Graphs shown on figure 35 indicate that a
large decline in the artesian pressure induces a large amount of saline
water to migrate upward from the lower zone. This upward migration
is often localized with the greatest intensity occurring in the pumping
areas, and it has little or no effect on the aquifer a short distance away
from the pumping.
Many wells in the more heavily pumped areas, such as Hastings,
East Palatka, and the farming area of Flagler County, have been greatly
effected by this upward coning of saline water during periods of maxi-
mum pumping. Several times the chloride content of the water in the
deeper wells more than tripled, and in the winter and spring of 1956
water from many of the shallower artesian wells in these farming areas
showed noticeable increases in chloride content.
Natural discharge in the Haw Creek and Crescent Beach areas
lowers the artesian pressures, and saline water continually migrates
upward into the upper part of the aquifer. In these areas water in the
upper part of the aquifer is rather saline throughout the year, and in the










REPORT OF INVESTIGATIONS No. 82


Well 947-116-1
A ao Crescent Beoch
15 Water level /\ -


I0 e\ a r360
9 \ -- 3500
Well 945-115-1
SChloride content / Crescent Bech
8/ --- 3400

6 3300

15
Sler level Well 941-130-4
near Hastings


-5 -- -100

300
/ 400
500





-------- 6------ ----------- I ------00

800
2000
0 Chloride c intent 1200


1800
12000


8 Well 940-134-1




4 400
\near Cods Clo -n


3 500
2 --eCh de content 600
700
800
900
I000
1100


Waer level Well 920:-119-2




SChloride content 15
-6 150
-7 175

225
51956 .957 tI i t t I I .1 t . I 9I53 250
1955 1956 1957 1958 I 1959


gure 35. Graph


showing the relation between the chloride content of water and
the water levels in artesian wells.







FLORIDA GEOLOGICAL SURVEY


Haw Creek area the water becomes even more saline when pumped
for irrigation during the growing season.
In the areas of natural discharge little or nothing can be done to
improve the quality of the water, but in areas of ground-water pumpage
the proper well spacing, depth of wells, and pumping practices can be
employed to allow the less saline water in the upper zone to be pro-
duced without disturbing the salty water at greater depth.

SUMMARY AND CONCLUSIONS

The principal results of the geology and ground-water investigation
of Flagler, Putnam, and St. Johns counties are summarized as follows:
Thick limestone beds of Eocene age underlie the area at depths
ranging from about sea level to more than 300 feet below sea level.
The limestone formations usually penetrated by water wells are the
Lake City Limestone, the Avon Park Limestone, and the formations of the
Ocala Group; the Inglis, and generally the Williston and the Crystal
River Formations. Except in southern Flagler and southeastern Putnam
counties the limestones of Eocene age are overlain by the Hawthorn
Formation of early and middle Miocene age, which consists of phos-
phatic sand, clay, marl, and limestone beds. In western Putnam County,
the Hawthorn Formation is overlain by less than 10 feet to over 130 feet
of undifferentiated clays, sands, and marls of post-Hawthorn to Recent
age and in the remainder of the area the Hawthorn Formation is over-
lain by 20 to 100 feet of marine clay, sand, shell and marl beds of
late Miocene or Pliocene age. In areas where the Hawthorn Formation
is missing the upper Miocene or Pliocene deposits directly overlie the
Eocene limestone formations. The surface of the area is blanketed by
about 20 to 140 feet of Pleistocene and Recent sand and shell beds.
A north-south fault in central Putnam County displaces the top of the
limestones of Eocene age from less than 20 feet to about 50 feet. West
of the fault the top of the Inglis Formation dips northeastward at about
9 feet per mile. East of the fault the Inglis Formation dips northward
at about 5 to 9 feet per mile from a structually high area in southern
Flagler County.
Ground water in usable quantities occurs in both the nonartesian
aquifer and the artesian reservoirs. The nonartesian aquifer yield
moderate to large quantities of water, particularly in central and eastern
Flagler and St. Johns counties and generally yields small quantities of
water to domestic wells throughout the remainder of the area. Th3
artesian reservoir consists of the principal aquiclude, the secondary arte-







REPORT OF INVESTIGATIONS No. 32


sian aquifiers, and the Floridan aquifer. The secondary artesian aquifers
are an important source of water in parts of eastern Flagler and eastern
St. Johns counties where water from the other aquifers are either too
highly mineralized or too difficult to obtain. The Floridan aquifer is the
major source of ground water for irrigation, public supply, and industry
in the area.
The nonartesian aquifer is recharged locally by direct infiltration of
rainfall and by upward leakage from the underlying artesian aquifers.
The secondary artesian aquifers are recharged both by downward infil-
tration of water from the overlying nonartesian aquifer and by upward
leakage from the Floridan aquifer. The Floridan aquifer is recharged in
western and southeastern Putnam County, probably in the area north
of Elkton in central St. Johns County, and probably in parts of Flagler
County. In each of these areas the water table is higher than the pi-
ezometric surface and surface-water runoff or water from the nonartesian
aquifer enters the artesian aquifer either where the aquiclude is thin or
absent or through sinkholes, lakes, and swamps which are hydrologically
connected to the Floridan aquifer.
Water-level records show a progressive decline of the artesian pres-
sure head of about 4- feet during the period 1953-56 and a seasonal
decline of as much as 20 feet in the farming area during the spring of
1956. This decline resulted from a combination of a deficiency of rainfall
in the area during this period and increased withdrawals of artesian
water, principally by irrigation wells. Between September 1956 and
September 1958 the artesian pressure head rose an average of 1.2 feet
throughout the area as a result of a cumulative increase of 4 inches of
above normal rainfall and a decrease in withdrawals by artesian wells
in the area. Artesian pressures in the area can be expected to continue
to increase if rainfall remains normal or above normal, and pumpage
does not increase.
The area of artesian flow has continually decreased since 1900
because of decline of the piezometric surface. It will continue to expand
and contract with future variations in the height of the piezometric
surface but it is improbable that the piezometric surface in the area will
be raised sufficiently to expand the area of flow to the size it was in 1900
because of increased use of water from the Floridan aquifer.
Analysis of data collected during five pumping tests in different parts
of the area indicates that the tested section of the Floridan aquifer has
ransmissibilities ranging from 178,000 to 360,000 gpd/ft and coefficients
of storage ranging from 1.57 x 10-4 to 9.4 x 10-4. The coefficients of
leakage were also determined from pumping test data and found to







FLORIDA GEOLOGICAL SURVEY


range between 1.5 x 10-3 to 1.75 x 10-2 gpd/ft3; the greater leakage
coefficient being in central and southern Flagler County where the prin-
cipal aquiclude is either thin or absent. The barometric efficiency of the
principal artesian aquifer was calculated to be about 37 percent and the
porosity of the upper 400 feet of the aquifer to be about 62 percent.
Based upon quantitative studies, current-meter data, and geologic
information the primary water-producing zone of the Floridan aquifer
in the area is the top 50 to 200 feet of the aquifer. In most parts of .the
area this includes the Ocala Group and the top of the Avon Park Lime-
stone.
Water from wells in the aquifers overlying the Floridan aquifer
generally contains less chloride than water from wells in the Floridan
aquifer. Exceptions to this are along the coast where the nonartesian
aquifer is contaminated by water from the ocean and in central Flagler
County where the aquiclude is thin or absent and highly mineralized
water from the Floridan aquifer leaks upward contaminating the shal-
lower aquifers. The nonartesian aquifer that supplies the Flagler Beach
municipal well field is presently being contaminated by water of poor
chemical quality. This water enters the nonartesian aquifer from a pond
that has flowing artesian wells discharging into it. The quality of the
nonartesian water in the vicinity of this pond could become similar to
the relatively salty water in the underlying Floridan aquifer if these
wells continue to supply the pond.
The chloride content of water from wells in the Floridan aquifer
generally ranges from 10 ppm in western Putnam and northwestern
St. Johns counties to several thousand parts per million along the coast
in eastern Flagler and eastern St. Johns counties and in south-central
Flagler County. Areas where the chloride content is lowest generally
coincide with areas where the piezometric surface is highest, and vice
versa. Water in the upper 200 feet of the Floridan aquifer generally
contains less chloride than water below 200 feet. This indicates that
contamination in the upper part of the aquifer is from saline water
from the lower part of the aquifer. This saline water probably is a
dilute residue of sea water that entered the aquifer during Pleistocene
time and has not been completely flushed from the lower part of the
aquifer.
Periodic determinations of chloride content in areas of large ground-
water discharge show that the chloride content of water from wells in
the Floridan aquifer varies inversely with fluctuations in the artesian
pressure head. As the artesian pressure is reduced by natural or arti-
ficial discharge, saline water from the lower part of the aquifer moves