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 Cover
 Letter of transmittal
 Table of Contents
 List of Figures
 List of Tables
 Acknowledgement
 Introduction
 Rocks and geologic time
 Earth's moving plates
 Florida's global wandering through...
 Geology and man
 Oil and gas
 Water resources
 Geologic hazards
 Waste disposal
 Environmental geology and Florida's...
 Reference
 Glossary of selected geological...


FGS



Florida's geological history and geological resources ( FGS: Special publication 35 )
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 Material Information
Title: Florida's geological history and geological resources ( FGS: Special publication 35 )
Series Title: ( FGS: Special publication 35 )
Physical Description: vii, 64 p. : ill. (some col.), maps (some col.) ; 28 cm.
Language: English
Creator: Lane, Ed ( Edward ), 1935-
Florida Geological Survey
Publisher: Published for the Florida Geological Survey
Place of Publication: Tallahassee Fla
Publication Date: 1994
 Subjects
Subjects / Keywords: Geology -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: edited by Ed Lane.
Bibliography: Includes bibliographical references (p. 61).
General Note: At head of title: "State of Florida Department of Environmental Protection, Division of Administrative and Technical Services, Florida Geological Survey."
 Record Information
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management:
The author dedicated the work to the public domain by waiving all of his or her rights to the work worldwide under copyright law and all related or neighboring legal rights he or she had in the work, to the extent allowable by law.
Resource Identifier: aleph - 002061098
oclc - 32688578
notis - AKP9194
lccn - 95622280
issn - 0085-0640 ;
System ID: UF00000124:00001

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Table of Contents
    Cover
        Page i
    Letter of transmittal
        Page ii
        Page iii
    Table of Contents
        Page iv
    List of Figures
        Page v
    List of Tables
        Page vi
    Acknowledgement
        Page vii
        Page viii
    Introduction
        Page 1
    Rocks and geologic time
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
    Earth's moving plates
        Page 8
        Page 9
        Page 10
    Florida's global wandering through the geological eras
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
    Geology and man
        Page 26
        Page 27
        Page 28
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
    Oil and gas
        Page 34
        Page 35
        Page 36
        Page 37
        Page 38
        Page 39
        Page 40
        Page 41
        Page 42
    Water resources
        Page 43
        Page 44
        Page 45
        Page 46
    Geologic hazards
        Page 47
        Page 48
        Page 49
        Page 50
        Page 51
        Page 52
        Page 53
        Page 54
        Page 55
        Page 56
        Page 57
    Waste disposal
        Page 58
        Page 59
    Environmental geology and Florida's future
        Page 60
    Reference
        Page 61
    Glossary of selected geological terms
        Page 62
        Page 63
        Page 64
Full Text


STATE OF FLORIDA
DEPARTMENT OF ENVIRONMENTAL PROTECTION
Virginia B. Welherael, Executive Director



DIVISION OF ADMINISTRATIVE AND TECHNICAL SERVICES
MImI Drew, Deputy Director of Technical Services


FLORIDA GEOLOGICAL SURVEY
Walter Schmidt, State Geologot and Chief










SPECIAL PUBLICATION NO. 95

FLORIDA'S GEOLOGICAL HISTORY
AND
GEOLOOICAL RESOURCES

Edited by

Ed Lans









Published for the
FLORIDA GEOLOGICAL SURVEY
Tallahassee
1 94


0qfljWrS Of ROfDRLLA q1%Wiq








LETTER OF TRANSMITTAL


FLORIDA GEOLOGICAL SURVEY
Tallahassee


1994


Governor Lawton Chils, Chairman
Florida Department of Environmental Protection
Tallahassee, FL 32301


Dear Governor COblis:

The Florida Geo&loical Survey, Division of Resource Management, Deparlment of Environmental Pro-
tactlon, is publishng as Special Publicalion No. 35, Flodidas Geotaklal History and Geobaical R.-
soiras, prepared by staff geologist Ed Lane. This puklatuon present the geological history l Florida
and its natural resources. As such, is a timely report that will be useful to the general public, teachers,
plan rs, and govemmenlal officials who need to know the Important aspects of Fbrlda's qeokgy.


Respecllully,


Walter Schmidt, Ph.D,, P.G,
State Geologist ard Chief
Florida Geological Survey



















































Prited for the
Florida Geologleal Surey

Trallah"Iss

WS O8~84O
ISSN 0085-0640






CONTENTS

Page
Acknowledgements ...... ... .. ............., ,. ,. ..... .... ............. vii
Irntroduclion ..,. ......... .... ....... ............ ... ... .. ..................

Chapter 1
Rocks: igneous, mtamorphlc and sedimentary .................... ,,........,... 2
Geologic time and dating techniques ................,. ..... ................... 3
Correlation of rocks ........................ ....................... 3

Chapter 2
The Earth's moving plates...... .............. .. ....... .............. .. .. 8

Chapter 3
Florida's global wandering Ihrough the gooloical as ............................. 11
Florida basernent rocks ........................................... 11
Precambrian, Palezolc and Mesozolc Eras ......,....... .................. 11
Cenozoic Era .......................................... ............ 15
Qualemary Period: Pleistocene and Recent Series ......,..... ..... 22

Chapter 4
Geology and man..............,,,............... ...... .................. 2
Early man and his nvrwronment ,,............ ....................... 26
Modern man .................,.... ................. ........... 29
Economri min rals ................ ............................ 2
Cem nt ......... ....... ...,... ............... 29
Clay.... ....... .... .. ..... .... ........ ... ..... 30
Heavy minerals ... ... .,.... ... ............... ... ... 32
Peat............................,...................... 32
Phosphae -..........,.,,. ....................... 2
Sand and gravel ...................,,.. ........ ...... 32
Crushed stone .................... ................ 33

Chapter 5
Ol and gas ................ ............ ,.. .......... .......... 34

Chapter
Water resources ................................................... 43

Chapter 7
Geoloic hazards ..............,,,,.. ....... ............ ................ 47
Karn t terrain ........... ..... , ...... ........... .., ........... 47
Flooding .............. ....,,,.. .................... .. ,.,....,, 50
Unslable soils ............. .... ... .............. .- ......... ... 50
Earthquakes ......... ..,,,...... ...... ... .......... ... ... .. .. 50
Global warming and sea level rise ................................... 68

Chapter
Waste disposal ....................,...,.... ......................... 58

Chty a
Environmental geology and Florida's lulure................. ...........,,,,..... 0o









Ralerences ...... ........ ............... ........ ..,,.... ,.. ...... 61
Glossary of selected geological lerms ....................... ................. 62


ILLUSTRATIONS

Figure

1. Relative ag dating and correlation between rock units ......................, ,... 4
2, Standard geologic column and lime scale ........................,.. .......... 5
3. Geologic map of Florida............................ ........................... .
4. Radioactive age dating and the age of the Earth .............,.......... ......... 7
5. Canminenlal plates and spreading cnters............. .......... ...... ....... 9
6a. Pattern of ages of North Atlantic oceanic crust ............,......... ....... f9
6b. Cross section showing sea-floor spreading .......... .... ........................ 10
7. Rock types ol Florida basement .................. .......,.................. 12
Florida's cohlinarilal drifting through time ................................... 13
9. Cenozolc stratlgraphlc column for Florida. ,. ... ..........--...............-.. 18
10. Sea level changes during the Cenozoc Era. .............................. ....,. 17
11, Oblique view of the Florida Platorm .,.........................................- .. 18
12, Gulf Trough Isolated the Florida Platform during the Ollgocer ....................,. 19
13, Gulf Trough filled by Miocene time ....... ....... .. ....... ...... ...... .. .... 19
14. Map of occurrence of Hawthorn Group sediments near the surface..................- 20
15. Major geologic structural element of Florida ....................... ............... 21
18, Pleistocene shorelines In Forid ............ ....., ................,.......... 22
17. Major topographic features formed by Pleislocene seas.....,.......... ............. 24
18. Plelsiocene mammoth ......................... ..... ..............27
19. Florida saber-toolI llgae and Pleistocene horses .......... ........................ 2
20. Pleislocene mastodon ............................. ..................... 2
21. Gianl sloth anid glyptodoni ......... ........ ........ .............. ........ . 29
22. Map of mineral mining areas in Florida ........................................... 30
23. Sulion dredge mining sand and gravel ...... .................................31
24. Open pit limestone quarry ............................... .... ... ........ 31
25. Cross section showing south Florida oil field ....................................... 35
26a, South Florida oil Iild location map ..................................... ..... ... 36
2 ,. Generalized straligraphic column for soulh Florida .....-.... .............. ........ 37
27a. North Florida oil field location map .......................... ............. ...... 39
27b, Geieralized stratigraphic column for north Florida ........-........-.............. 40
2B. Graph of historical trend of oil and -as production ..........."......... ..... .... .. 41
29. Hydrologic cycle .............., ..... .... .......... ..... ......... ........ 44
30. Correlation char tlor aquifers and confining units-..- ..............-.. ..... ........... 46
31 Evolution of kart landscape ..................................................4 4, 49
32. Aerial photograph of the Pitl landslide. Gadsden County ........... .............. 51
33. Photograph of the scarp of the Pitt landslide .............. ....... ...... .,..... 51
34. Water well record of 1979 Colombian earthquake ................................... 2
35. Water well record of 1990 Philippine earthquake ... .. ...... ,,.. .... ...... ...,.. 53
36. Water well record of 1 964 A'lakan earthquake ..................................... 55
37. Coastal changes In Florida due to sea level rise ................................... 67
38- Early method of landlilling forwaste disposal.,........-.. ......- ................. 5B
39. Marion County landfill, showing new cell ............................. ............ 5..
40. Marion County landlill, cross section of new cell ............ . ........... .... 59








TABLES

1. Flaride oil fleW discovery well data ................... .... ............. ... .. 3B
2. US 0I known earthquakes felt in Foaidm ..,.. .......... ......................... 53








ACKNOWLEDGEMENTS


The editor wishes to thank i eo following staff of Ihe Florida Geological Survey who were contriutng
authors for various sections of the manuscript: Jonalhan D, Arthur (basement rocks, and Precambrian
and Paleozoic eras), Paulatle BoAnd (Mesozos era and carbonate platforme, Kenneth M. Campbell
(economic minrrals, water resources, and waste disposal), Jacqueline M. Lloyd (oil and gas), Frank R.
Rupert (Cenozoic era, early man and his environment). and Thomas M. Scott (Cenozoic era). The
manuscript was edited by te respective author, Jacquellne M. Lloyd, Thomas M. Soot. Walter Schmidt
and James Jones Cindy Collier also asslsted In preparing the rrmanuscrlpL All Illstrallons were drawn
or complied by Ed Lane, except as noted.











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


Pwatfus 4Wi, an e linc sielnoid (sand dNlail, found in Ihe
Avio Park Fornman iEaQn l- X1. Drawn by Fank Rupert, FGS.






SPECIAL tUUBLICATION NO. 35


FLORIDA'S GEOLOGICAL HISTORY
and
GEOLOGICAL RESOURCES
COMPILED AND EDITED BY
ED LANE
PG 141



INTRODUCTION

This book Is a synthesis of geological facts and
the manner in which they have been used 10 re-
construct the geological history of Florida. Basic
geological concepts and techniques are pre-
santed in order to provide background irforma-
tion that is necessary for discussions ol the top-
Ice. It is Intended to be succinct, yet broad enough
In scope to cover the important aspects ol Florida
geology. As such, it will be suitable as a teaching
aid, and as a source book for those who with tO
dig deeper Irto Florida's geological history.

GEOLOGY reans "the science ol the Earth-. Ge-
ology is the branch of natural science that stud-
las the Earth, its rocks and minerals and the
changes it has undergone or Is undergoing. Some
specialized fIlds ol geological study Include:
hydrology (water resources), pal onlology (fos-
sils and ancient life), stratigraphy (Ihe formallon,
composition, sequence and correlaton of rocks),
geomorpholoy (Ihe form of the Earth's surface Colpoc
and cangres that take place), pelirogy (history
of rocks, their origins, changes and decay), and FIodsasol
engineering, mining, and petroleum geology.- M "
MdnWon CW
Words in bold type are defined in the glossary at
the end of the book.







FLORIDA GEOLOGICAL SURVEY


CHAPTER I


ROCKS and GEOLOGICTIME




th*0n"M*MFr anWWMla, 1 WkVr0o4 end'
Asoom mit sunlr'rg asog Flarli% mgat
Wm?, is a eqhcte qmlirm WMW of 0NW ma-o
ibis buul debris mui mad. X1 (FliPWt 116W


ROCKS

ED LANE PG 141

The Earth's crust is not uniform. HI surface and
interior are made of an almost endless variety of
rocks, each having its own distinctive characler-
stics, such as minerals, color, density, porosly,
and hardness. Geologists classify rocks accord-
ing to their origin.

IGNEOUS ROCKS

Igneous rocks (Irom the Latin word for "lire) are
rocks that are formed deep within the Earth's mobl
ten interior. Sometimes they are forced out of Ihe
Earth's interior through volcanoes and appear on
the surface as lava, Examples of Igneous rocks
are granite, basalls, obsidian (volcanic glass),
and pumice (Ihe porous. bubble-filled lava that
floats on water). There are no igneous rocks ex-
posed at the surface in Florida, although they
have been found several thousand feet below the
land surface In deep oil wells.

METAMORPHIC ROCKS

Metamorphic rocks (from the Greek words for
"*clanged in lorm") are formed deep beneath the
Earth's surface. Originally, they were igneous Or
sedimentary rocks that were transformed by the
tremenndou heat, pressure, and chemically ac-
tive fluids to which they were subjected after budIal
in the Earth. Examples of metamorphic rocks are
slate (metamorphosed shale), marble (metamor-
phosed limestone), and quartzite {melamor-


phased sandstone). There are no mntarnorphic
rocks exposed at the surface in Florida, although
some have been found In wells at depths of sev-
eral thousand feel.

SEDIMENTARY ROCKS

Sedimentary rocks are those thai were formed at
the Earth's surface, either by accumulation and
cementation of Iragments of rocks, minerals, and
organisms, or as preclplitaes from sea water,
surface water or ground water. Debris from ero-
sion and weathering commonly lorm sedimentary
rocks, For example, a sandstone and a conglom-
erate are rocks that are the cemented counter-
parlt of loose sand or gravel deposits, respec-
tively. One group of sedimentary rocks found
throughout Florida are limeslones, which are pre-
dominantly derived Irom the calcium carbonate
tests of mdrin organisms and algae. A common
feature of these rocks which Indicates their ma-
rine origin is the presence of fossils of maine
organisms. Some limestone", called coquina, are
composed almost entirely of shells of marine ani-
mrale that became cemented together after the
animals died. Many Of the sand and clay depos-
Its thai cover Florida were transported and de-
posited into sea water by streams. Some were
then reworked by coastal and marine processes,
sutCI as shoreline erosion and acrelttn.







SPECIAL PU BLICATION NO. 35


GEOLOGIC TIME
and
DATING TECHNIQUES

The Earth Is very old-ovr lour and a half billion
years-4,500.O.0,000 years. This length of time
Is nearly impossible to comprehend In terms of
human evenls or even Illetimes. How earth sci-
entists determine geologic time forms Ihe basis
lor many of the key prlnclples that have helped
to explain the mysteries of our planet's and
Flrida's geologic histories

The secrets of Earths age are hidden in its rocks.
Interpretalion oi these secrete may be difficult
because rocks can. and often do, vary greatly in
age from place to place; and sometimes there ar
gaps in the rock-record, with layers missing.

Geologic time IS measured in two ways: a re~-
t/ve time scale, based on the sequence of layer-
ing of rocks; and an absofuFe (or atonic) ime
scale, based on the rate ol radioactive decay of
certain elements in rocks.

One lundamentaJ principle of relative age daling
is the Law of Superposition. which states thai: in
any sequence of edimentary strala that has not
been disturbed by folding or overturning since
accumulation, the youngest stratum Is at the top
and the oldesl is at Ihe bottom, Relalive age dat-
ing dalso 1 done by using a second baslc prin-
ciple of geological correlation; namely, that dis-
tinctive marker fossils are found only In rocks of
certain ages. Chronologi correlation, as used by
geologists, means the determlnatlor of the ap-
proximate equivalence In geologic age and strati-
graphic position ol two rock strata thai occur in
different areas of the world (Figure 1).

CORRELATION OF ROCKS

Paleontologlicl studies of fossils around the
world have shown Ihat. throughout geological
time, countless species of animals and plants
have appeared, flourished lor millions oI years
and, then, either died out (became extincl) or
slowly changed (evolved) into signllcantly
dlifrent plants or animals. In geological terms,
this lile-span of a distinctive spades Is ils age
rang.


Another important aspecl ol studying fossils is
the dete rmnation at 1heir geogaphic distriution:
in other words, "Where In Ihe world did they lle?"
As Is true with plants and animals today, some
fossil specie have been found to have had world-
wide distribution, while others have only been
found in restricted areas or regions. This can best
be Illustrated by considering the relationship of
any animal or plant to its environment, The physi-
cal characteristics of every plnt or animal re-
qulres that t Ive In certain and ofeln restricted,
environment. Oysters, for example, are restrict-
ed to living on Ia bottom of bodies of brackish
water, Therefore, II one found accumulations lo
losil oyster shells In a stratumn a rock, II could
reasonably be assumed that the rock's con-
stiluents had been deposited In a body io
brackish water.

These two principles have enabled geologists to
Identify rocks ol the same general age wherever
they are found. The actual age of the rocls, In
terms of years, however, was not known. The rock
units could only be placed in a reoaiJve se-
quence-either older or younger than other
adjacent rocks, On the basis Ol such relative age
dating in Europe, 1he talndbad gailogac cohumr
was constructed during the 1800s (Figure 2).
FIgure 3 is a geologic map and a geologlc col-
umn for Florida showing rocks that occur at or
near the land surface. Also given on the stand-
ard geologic column in Figure 2 are approximate
ages that are derived from radioactivity studies,
summarized In Figure 4,







FLORIDA GEOLOGICAL SURVEY


North Florida


South Florida


land


-
mi

z
0
C


-a
ml
0
I
0
1
rl


surface



















a
S
a


a





0


Z "-r b ;, t .. 1






Q-temiM w.u. ,,_ ~
-IMP




mew




Figure 1. Relative age dealing and correlaon between rck units using IosJll.Tho thnr specie at
mlIcrsfopk anlmla, called toramlntifera occur in Florida rocks of different age sThr occurrenc
In rocks throughout the stae Indicate the redulve ages of he strata In which they a tound. Photo-
grapha by Frank R. Rupert.








SPECIAL PUBLICATION NO. 35


millll
PERIOD

HOLOCENE
z

PLEISTOCENE


0
III 24
U OL110C ENIE
-EOCENE
PA LIMOIENE


CRETACEOUS


JURASSIC


TRIASSIC


PERMIAN

PENNSYLVANIAN

0 I MISSISSIPPIAN


DEVONIAN

SILURIAN


ORDOVICIAN


CAMBRIAN


PRECAMBRIAN


S141



S195


230

280

320

S345

395

43S


500

570





4.50


I8I
EVENTS

SEvoluiion of man

: lee ag. .
; Ic ..:.. 1 lll: l l :B


0:

: Prollferation of mrammals





Last dinosauts
a First primates
First flowering plants


Dinosaur~ dominant
First birds

First dinosaurs
First mammals

Major extinctions ol many
marine forms oa life

First reptiles

Scale trees, seed eIrns

First amphibians
Jawed fishes

First vascular land plants

Burst of diversificatlon of
soft-bodied animals

First fish
First chordates

First skeletal forms
Slams, trilTobites

First soft-bodied animals
(sponges. jellyllsh)

0 Simple, one-celled life


FIge L Stwandurd geologic column and Jim* s*"I.Tht systmo divisions aren appllir the wcwid
ovw.The nottilon MrM her* and throughout the timt mean.: million yom' ago,


-U


1


.........









FLORIDA GEOLOGICAL SURVEY


Sur


ra
-w


Figur 3. Geologte rmp of Florida showing *e locations ol roc tm occur at or nw the surtfm
(aftw Rupert, 199). Sr Rigur 9 for dtaled tratigraphle omnawm.









SPECIAL PUBLICATION NO. 35


71 r m n yer

713 isMlliooa y-fM


(, i f .. .

1: 12 amn LM-


Fpgur 4. Radioacive age dating and th age ol th earth. Radioactive elmnwnt asch a thorium
and uranlum, aponranously disintegra t to orm new element.The rde at which ach radoetle
ainemet dintegratl I unique to tat shment, and each element's deay rat has ben det-
mnded by skcntlfts. Decy rans e given In nterm ol hallt. In years.Ths la the time required or
one-hIf ol the radloactIve atoms iitlly present In element t to dlelntogrte and change Irto a
new element For eumple, uranlum-3M with a ha-It* of 713 million yeur, decays to form the
stabk elemewt lad-207. By carefully meauring ui mounw of radioactive elements In rock,
geloglats can calcuim e It ages of the rocks.Whi the results of studies of radoeclve elements In
mirnrals from rocks all over the world, geologists hve been abe to assign bslute ages, In years,
to the standard geologic column n Figure 2 Baed on radioctive dating ltuchiques scientists
alculre thw earth Is about 4.5 bHllon yar old.


~ -rr4
U .1 uI JS


Bo mne dwugg JHpemnrken oralapnWM ou in the Flridln CompnTry O incy mbin, 1I Now on dLspr hi Om lhbb
ofai W Ftodrr OGOOk di d Bury bulMIMigAlhlwtianeL H Rupet, 19M.








FLORIDA GEOLOGICAL SURVEY


CHAPTER 2


EARTH'S MOVING PLATES


Wold abaM 5C ciiEin laws Wi hftmu
faudined). bserd an preosw patin
movemnwl nirlu, Segi sM dOuwge
acw in Owm t Anwl.. mid waudi.
em Calift W upp19pighm Ales*.


EARTH'S MOVING PLATES

Ed Lane PG 141


How did Florida gel where it Is and in ts present
shape? The answer to this question lies in the
restless nature of EarthW crust, Earth's uriace
is active and mobile: mountains rise-sea floors
are created-and continents move. Until a few
decades ago such ideas bordered on science fic-
tion, even to geologists. However, evidence has
been accu mulating for the past 30 years that Sup-
ports the basic theories ol how the present shapes
and arrangements of Eadh's contents came to
be. These early theories of sea-foor spreading
and continental drift led to our current under-
standing of plate tectonics.

The noion of continental drit is based on the lact
that the so-called solid" rocks thai form the Earth
are capable of moving. Plate tectonics theorizes
that large chunks (plates) of 1he Earth's colder,
upper crust are capable of moving slowly (like
rafts) on top of deeps r, hoter, and more luld rocks
in the mantle (Figures 5, 6a. and 6b). Geologists
have identllied seven large plates on the Earth's
surface, with 11 or more smaller plates. The ple-
lure that has emerged from recent discoveries In
geology Is a simple one: lhe Earth is girdled by
numerous linear spriadlng enters dominated
by a continuous 40,000-mlle-long system of nmd-
ocean fdges, such as the Mid-Atlantic Ridge and
Ith East Pacilic Rise (Figure 5), These ridges form
portions of the plate boundaries and have cracks
{rifts) along their crests. Lava from the Earth's
upper mantle is more-or-less continuously forced
out from the rllft along the ridg crests, produc-
ing new (young) rock. This process of creating
new oceanic crust forces adjacent plates apart
and is called sea-floor spreacfing. Sea-looar


spreading causes the continents to migrate or
"dr~l.' Raes of spreading vary from place to place
along the mid-ocean ridges. For example, the
north AtLantic basin is growing wider by approxi-
mately one inch per year, while the south Atlantic
basin is growing wider at the rate of about one
and one-half Inches per year,

What happens when all these plates move about
over the Earth? Spreading In one place will cre-
ale a collision in another. Plalis come logather
In different ways. They may slide past each other
along their margins, along faults, as does the San
Andreas Fault in California, which is part of the
boundary between the North American and Pa-
ciic plates (Figure 5), The many earthquakes of
that region are the result of the Iwo plates grind-
ing past each other, in some places at the rate of
several inches per year. Or, one plate may slide
under another In a geologic process called sub-
ducllon, in which case two things may happen.
A deep oceanic trench may be formed, such as
the Aleutian Trench, Alaska (Figure 5). Mountain
ranges may be created as the edge ol the over-
riding plate is lifted and buckled up, such as where
the Indian continental plate is pushing up the
Himalayas, which are on the southern edge of
the Eurasian plate. Accompanying all of this
trench and mountain building are arthiquaks
and volcanlc actively. Fortunately for Florida, most
oI the earthquake and volcanic activity takes place
along the leading edges of the plates. Because
Florlda Is on a passive Interior part of the North
American plate, it seldom feels any quakes and
has no volcanoes.









SPECIAL PUBLICATION NO. 36


Figure 5. Swue. largi plate account r mort of the arths surfae. Plat margin and pr"eding
ter are show In red. Arrows dtO relative motions, with th African plate assured to be
st1onary. Several smaller places a also shown, much sknpliled wnd compiled from many source.


Figure Pattern of ages of North Atlantic ocenic crul. The Atlantic Ocan ha been opening or
ovr 20 million years and is still widening t th rats of a fuw contimtlrs per yea. Crous seMton
A-B i Figure lb (modMed from: Thackhry, 198I).













older mmoolic Ct~E ~Y~lbt~
0004filla CM6
Nof k h Afflorloan
64"110111 01191 1"1I Ireef ful


Orw IIrae rul


)AIb- ATLANYIG RIDOE.
.nOIrlu rift of topridreg ggim
and ridge


Figue b. West-to-east croe sdclton showing bwile ampactl of platl te~ onis mid seeloor spreding: (1) qp-
welling cocrencurrntla of moren mantel rock splt the continntal cant apal, rating rttfi rnd xudlng new
oceenie crust (2; ocean cruel trave away Irkom spresdng centr, (3) moving the Hgter conthLntal plate (4)
with Tr wform faums realt omletd by unween tenbronal ctd ompreseil force, on the crust modeledd from
Thackray, I9o)


I ~


O ~UpW911I9 Q1 01 #ft Molll i








SPECIAL PUBLICATION NO. 35


CHAPTER 3


FLORIDA'S GLOBAL WANDERING
THROUGH THE GEOLOGICAL ERAS


Jonathan D. Arthur PG 1149,
Paulette Bond PG 182, Ed Lane PG 141,
Frank R. Rupert PG 149, and
Thomas M. Scott PG 99

FLORIDA BASEMENT ROCKS

Rocks of Precambrian, Paleozoic and Mesozoic
age occur several thousand feet below the sur-
face of Florida (Figure 7). These older, deeper
rocks are either igneous, metamorphic, or sedi-
mentary and may collectively be termed base-
ment rocks. In north-central Florida, these rocks
have been penetrated by oil test wells at depths
of 3,500 feet below the surface. The distance to
these basement rocks gradually increases away
from this region, reaching depths of more than
two miles below the surface in the western pan-
handle, and over three miles in south Florida.

Figure 7 is a generalized geologic map showing
the distribution of basement rock-types in the
subsurface of Florida. Basement rocks of south
Florida are primarily basalts which were formed
during the Late Triassic and Early Jurassic Peri-
ods. These basalts also occur in the subsurface
of northern Florida where they are interlayered
with Mesozoic sedimentary rocks. In central
Florida, the basement is granite and minor
amounts of metamorphic rock. Radiometric age
determinations of these rocks indicate that they
were formed during the Early Cambrian Period,
about 550 million years ago. Rocks very similar
to these also occur beneath portions of the Florida
panhandle. Underlying most of northern penin-
sular Florida and the central panhandle are sand-


stones, siltstones, and shales which are early
to middle Paleozoic in age. The ages of these
sedimentary rocks were determined by their fos-
sil content, which included brachlopods,
crinoids, and mollusks. Not only do these fos-
sils tell scientists about the age of the rock in
which they occur, but also provide clues about
the environment in which they lived. These or-
ganisms lived in cold sea water along the margin
of an ancient continent.

PRECAMBRIAN, PALEOZOIC
and
MESOZOIC ERAS

During the Late Precambrian, about 700 million
years ago (mya), terrain that was to become
Florida was part of an ancient supercontinent,
which was composed of what is now North and
South America, Africa, Europe, and other land
masses. More than 600 mya, this supercontinent
split apart-most significantly North America from
Africa. Later, in the Paleozoic, the tectonic forces
which had split the supercontinent continued to
operate, driving the detached land masses to
migrate together again in a collision which formed
another supercontinent, called Pangea (Figures
8a and 8b). The tectonic cycle continued with
Pangea rifting apart again (Figures 8c, 8d, 8e),
as had the first supercontinent, and during the
next 200 million years the Earth's plates migrated
to their present-day configuration.

So where does Florida fit into this story, espe-
cially if it was not part of the "North America" that
existed during the early Paleozoic? At one time,


Possible location of the Mesozoic suture zone,
the boundary between ancient Africa and an-
cient North America, formed by their collision
(Nelson et al., 1985).








FLORIDA GEOLOGICAL SURVEY


Ns


i m Tr ia..IC red-b eds eid d ibbm so InW ru iIo ri

0 Eeriy to Middle Mesozoic extriusie rocks

Oirdaybeia., Cevonian sedlrnsn~afy rocks

Lete P-rcambrliri Emily Cambrlin
Inirusivp end extrupuiV rocks

Approximmis cointac beipieen rock hytaa


Figure 7. Rock typ of the Florida basement These deeper, loWw rocks are Eud 0Ionly ral
thousand fee below the surface. Compled by Jonathan I Arthur.


scientists believed that the basement rocks of Ihe
southeastern Uniled Slales, Including Florida,
were a subsurface extension of the Igneous,
metamorphic, and sedimentary rocks that are
exposed in the Appalachian Mounlains. However,
recent research indicates that the area thai was
to become what we know as Florida was a part of
northwest Africa. In the last 25 years scientists
have found distinct similarites between Florida
basement rocks and subsurface rocks In north-
west Africa. Certain Florida sandslones, silt-
slones, and shales as well as the fossils which


they contain are very similar to the rock
sequences and fossil assemblages which occur
in northwest Africa. ThA Igneous and metamor-
phic rocks ol Florida are comparable n rock-type
and age to those ol northwest Africa, Also, when
the continents are fit back together In order to
envision the layout of Pangea (Figure 8b), the lo-
calion of the various types of rock in the base-
ment are better understood If they are considered
to have been a part of Afca. The Florida base-
ment seems to provide a missing piece Of the
Alrican puzzle. Various magnetic properties within








SPECIAL PUBLICATION NO. 35


Figure ft.Their uvml uI d-mass Pange about 230 millin Flgwo 8B. Deta0 l of Apirs
years age (mya). Fulum-Flarldm Is shaow In rnd. Figure s f uhoveing tkof Afta arnd
&4% ~tr Okta and Holden, 19Mh. Norih Amsrtc&Dashd lhw
approximatea S,aOGD-fee
depthr eontur.


Figure B. Triaslic perod, about 195 my~ At-
lante Ocean ha begun to open. Plate bound-
ries In redl arow* show dlreloin of plats drifl.


p4d, Jursaule period, about 140 myw.p
Atlaiiil Ocmn has begun to open.








FLORIDA GEOLOGICAL SURVEY


Figure Se. Cretaceouu prfad, about 65 my. AM pwrewt ocemn have opened. Indi Is on Its way to
collide with Aila and er de t Himalayan Mountains, ard f ure*-lorl drifts toward Its premm
localdon.


the Florida Paleozoic rocks also match better with
those of Africa than those of North America. The
Mesozic auture-the boundary between ancient
Africa and North America which was formed when
they collided to form Pangea-rnay be located in
he subsurface of southern Georgia. Scismensts do
not know exactly where the suture zone between
North Americl and the ancient Afro-South Amedr-
can plate is located, but attempts have been made
to find it, Using information Irom deep wells In
north Floida and southern Georgia, geologists
think Ihey may have found the ancient suture
zone. A*so, a 1985 edlamic survey across south-
ern Georgia indicated that Ihe suture zone may
be there. Although indirect in nature. Iis evidence
supports the Idea that Florida was once a part of
Africa. I the boundary between ancient North
America and Africa is now located north of Florida,
then the deep Paleozoic roCkS Ol Florida repro-
sent a rifted-ofl portion of Africa.

In every comparison ol geologic Informatlon, the
affinity with Africa becomes more apparent and
the resemblance to Paleozoi North American
rocks lessens. Because of the current theory
that Florida was once part of northwest Africa,


geologists refer to the basement of Florida as an
exotic terrain.

The Atlantic Ocean basin began to form In the
Late Triassic when Pang$e began to split (Figure
8c). By mid-Jurssic time riling was probably
complete. To the east of proto-Florida a spread-
Ing center was creating new sea floor for the
young Atlantic Ocean; this spreading center is
now called Ith Mid-Atlantic Ridge (Figure 6b). As
the new sea floor spread outward to both sides
of the rdge, the North American continental plate
was forced away from Africa (Figure Be),

By the late Middle Jurassic Ihe spreading center,
which had begun earlier to pour out basaltic lava,
gradually shifted its posllLio to the east. The lava
Lows cooled and hardened, forming new ocean
floor or oceanic crust.

Near the margin between the nrewly.ormed oce-
anic crust and the older cornlnental crust, a basin
began to slowly lorm. At first this sknkng (or sub-
sidence) occurred mainly because the basatic
crust shrank as 11 cooled. As the crust continued
to cool and shrink, various types of sediment were








SPECIAL PUBLICATION NO. 85


carried into the basin. The weight of this accumru-
lating sediment also forced the cruel beneath the
basin to slnk. This extremely gradual sinking was
essential in the early development of the carbon-
ate Florda platform during the Cretaceous.
A carbonate platform is an area where great thick-
nesses of carbonate rock have accumulated in
the past. Carbonate sediments are continuing to
accumulate to the present day an the Florida Plat-
form and on modern carbonate platforms, such
as the Bahama Banks, east of Florida. Carbon.
ate rocks on the Florida Platform are limealones
(calcium carbonate, CaCO) and dolomiles (cal.
cium-magneslum carbonale, CaMg(COO,)~.

The calcium carbonate which makes up the rocks
associated with carbonale plalforms is produced
by various organisms which live In marine envi-
ronments. When the tiny animals that live in coral
reels die, the reefs (made of calcium carbonate)
may be preserved as one type al limestone. Some
varieties of seaweed (afgae) have the ability to
secrete Iraglle skeletons of calcium carbonate.
When the algae die tiny crystals of calcium car-
bonate fall to the sea floor and form carbonate
mud, or lime-mud. This carbonate mud Is pre-
served as another lype of limestone. These are
only two examples of the sorte of organisms which
construct calcum carbonate skeletons as parl o
their life cycle. If a carbonate platform is to form.
these carbonale-producling organisms must be
able 1o grow prolilically. The water in which the
organisms live must remain shallow, since some
of them require light to survive.

Minor amounts of anhydrile calciumm sulfate.
CaSO) ocur In the thick section of Cretac ous
carbonate rocks of south Florida. Anhydrite forms
today in very dry climates such as Ite Persian
Gulf. Generally, it seems to form when sea water
flows into a shallow basin which Is cut ot from
additional sources of water. In that situation Ihe
sea water evaporates until eventually anhydrite
is formed by precipitation. The preenice of an-
hydrite layers In the thick carbonate accumula-
orns of south Florida sugest$ that at sometime
in the past the climate may have been hotter and
much drier thai it is now.

The Mesozoic Era, from about 250 million years
ago (mya) to about 65 mya, is popularly known
as Ihe age of dinosaurs" because they were the
dominant lorms of Jlfe for over 150-mlillon years,


Although dinosaur lossils occur In many places
in the world, none have been found in Florida,
and a took at Fig ures 2 and 3 will help to explain
why this is so. Dinosaurs became extinct about
65-million years ago, and the oldest rocks that
occur al or near the surface In Florida are Middle
Eocene age, about 45-million-years old, depos-
ited some 20-mlllion years after dinosaurs be-
came extint. While it Is poslble that dinosaur
losslls may exit In the Cretaceous roccs under
Florida, the closest ones would be several thou-
sand feet deep, Florida's oldest verebrate fossil
was recovered In 1955 during oil test drilling
near Lake Okeechobee. A well core brought up a
partial skeleton of an aquatic turtle from a depth
of 9,210 feel from rocks of Early Creaaceous
age. The core hole Jusi happened to be in posi-
lion to penetrate the rocks where the fossil was
embedded.

CENOZOIC ERA

The Cenozoic Era In Florida is represented by
sediments that were deposited during the last 65-
million years of geologic times (Figure 9). Sea-
level Iluciuations throughout the 'Cenozoic played
a major role in creating the present configu ration
of Florida, though the processes of sediment
deposition and erosion. In general, the sea level
during the early Cenozoic was significantly higher
than the present level. Throughout the Cenozoic,
sea level flucluated considerably along a broad
general trend of calling sea level since the end of
Ihe Cr leacous (Figure 10). This general sea lovet
trend has superimposed upon it many shorter
duration fluctuations, both sea level rises and
lalls- The geologic record of Florida reveals
unconfolritle where sedlments are absent due
to nondeposttlon or erosion In response to sea
level fluctuations- Geologists believe that the
Cenozoic sea levels in Florida have flutLualed
from several hundred leet or more above Ihe
present level to more than several hundred feet
below present sea level.

The Cenozoic of Florida is represented by two
groups of sediment;: the Paleogene and the Neo-
gene-Ouaternary (Figure 9). Carbonate rocks pre-
dominate In the rock-record of the Paleogene In
Florida while quartz sand, sills and clays doaml
nate the Neogene-Quaternary. The carbonate
rocks are principally limestone and dolomile with
varying but generally minor percentages of









FLORIDA GEOLOGICAL SURVEY


NIQRTH FLORIDA l


1 IE


CypJd49head Fm ;
ICluiroitil Fml.)


AI3ENT


2tnutvlil. Pfm

SCosaawhtatlim
a

u Ml.te iad Fm.


Panniy Farms Fm



"Su ii LI.


SwwuIrne Ls.


L. 0
Loer


a 1

p"
p--


I7----
Av -Io Part Pn.
(Includel i ~wm
'" CiLy L.zA


Oldumeif


I
MESOZOIC ERA


Cedar Keye Fm.


SOUTH FLORIDA


TArcadia Fo,

T i 'bHM 1 zr 11g


* NOTE: PaIplogrno
dratigraphic column in south
Floria Is Bane as north


clay
Gravel

C coqulrlla|Nil bodi
Ilmelone


n\\ hydriLm
4 gypsum
p phiophatic
S phOsI2hLariH


I- pproilMltyiI 4 5


Flgure Conozo4c Era stralgraphic column showing 1he formations that occur n Florida.


2

W


I *1;;"


.1








SPECIAL PUBLICATION NO. 35


CENOZOIC IERATHEM
TERTIARY 9aSSTEM
PALE001141 HEOEnE ___
PALEOCENE EOCENE OLIGOCENE HIOCENE SERIS
Lcw*l I Upp.W Lo*Vr W ddi. Uppwf LDW L U004F LM Ml7.d. I p7.j L U
Um


55 60 IlL 50 42 dO 1 ~O 10 20 115 i


-Rao




-50 Md
20A y fin &ad


Frgu0r 10. Sea level chwpan during the CAnoAolc Era (alter Haq at a., 1987).


evsporites. The evaporiles present in the Ceno-
zoic rocks are gypsum (CaSO .nH,0) and anhy-
drite, The evaporites are present as thin-to-thick
beds and as pore lilings In the carbonate rocks
comprising the lower portion of the Paleocenr
seaclon. The evaporites formed In response to
estrcted circulallon lo the sea water allowing
evaporation to concentrate the minerals in solu-
tion. The minerals were then deposlled along with
the carbonate sediments.

The Florida peninsula Is the emergent portion of
the wide, rlaivly Ial geologic feature called the
Florida Platform, which lorms a rampart between
the deep waters of the Gulf of Mexico and the
Atlanic Ocean (Figure 11). The Florida peninsula
Is located on the asterm side ol the platform. The
edge of the Florida Platform Is arbitrarily defined
o be where water deplh is 300 leet. The edge al
Ihe platform les over 100 miles west of Tampa,
white on the east side of Florida It aes only 3 or 4
miles off the coasi from Miami to Palm Beach.
Within relatively short distances Irom the edge of
the platform water depths increase more sharply,
eventually reaching "abyssal" depths ol over
10,000 feet, creating what is known as Ihe Florida
Escarpment. Diving expeditions along the escarp-
ment west of Tampa. with the deep submersible
Alvin, found the escarpment there consisted of a
gigantic limestone dllf that rose over 6,000 feet
above the 10,700-feet-deep Gulf floor. Based on
evidence from oil exploratory work, II has been
estimated that carbonate and evaporlilc rocks


may underte south Florida at depths greater than
20,000 leoe

The Florida Platlorm, during the Paleogene, was
very much like the present day Baihama Banks
with carbonate sediments forming over a large
area. The carbonate sediments formed due to
biological activity and. Ior the most part, are made
up of whole of broken fossils. These fossils in-
clude foraminMer, bryozoo, malluaks, corals
and olhr forms of marine life.

Very little aelllcilatlle material was able to reach
the Florida Plallorm due to the presence of a
marine current running through the Gulf Trough
(Figure 12) which transported these sadimenls
away from Ihe plaltorm, This current was slmllar
to Ihe Gulf Stream today. Another facor was that
the Appalachian Mountains. Ihe primary source
lor the siliTiclasi sedimerls, had been eroding
for millions of years through the Mesozoic and
early Cenozoic. As the mountains were reduced
by erosion, Ilmlted amounts of siliciclastlcs were
produced and carried by streams and rivers to
the ocean where currents carried the sediment
away Iram the Florida Platform.

In the mid-Canozolc. late Paleogene, the Appa.
lachians were uplifled and erosional rates in-
creased greatly, providing a flood of siliciclastic
sediments which eventually killed the Gulf Trough.
With the filling of the trough, the silkiclastic
sediments encroached upon the carbonate


I








FLORIDA GEOLOGICAL SURVEY


FIgure 11. Oblique view of the Florlda Platform and Florida
Eacarpmenm, showing ther Ilands of the Florida Keys fringing Its
smouthrn rim. The pal above preaSMt sea level Is Florida (Larn


deposlting environments, replacing them with
sands, eils and clays (Flgure 13), In northern
Florida, the siliclclasltc sedimens appear very
early in the Miocene while in southern Florida
carbonates conllnued to be deposited until at least
mid-Miocene. The siliclelastlc ad1edirns spead
southward mosl rapidly along the easl coast of
Florida in response to there ore vigorous coastal
condition orn the Altantlc coasllne.


The segments deposited during the Neogene are
pdmarily quartz sand, sits and clays with vary-
Ing amouni of limestone, dolomIte, and shell.
With he exception of lhe Pilocene Tamlam For-
malion in soulhwestem Florida, the Neogene
carbonates occur as thin beds and lenses
disseminated in the siliciclaelic selmenls. De-
posits composed primarily of shells with subordi-
nate amounts ol sands and days become vry
common Inhe Pliocene moer much ol Florida.








SPECIAL PUBLICATION NO. 35


iii~- w_ -- ... ... ...
Figure 12.Through Ollgocene time the Florida Figure 13. Slicktlcl asdim nta had filled the
Platkfom Was shallow, marine limestone Gulf Tough by Mla. limne and ecrmached
bank envlronmenL COerrnts through the Gulf down Ihw penrsmula, covering hw limesaone
Trough div led sands, slIts and ~y that environments.
wee eroding off the Appalechian Mountains
to the north.


The beginning of the Neogene nol only marked a
dialnct change In sedlmentallon bul also the ini-
itinri of phosphale deposition in Florida. The oarn-
ditons leading to the rdpoWoItn io marine phos-
phates are variable but specific conditions are
thought to be required. One ol the mros important
factors i the upwelling of cold, nutfenl-rich, phos-
phorue-laden water from lhe dep ocean basirn.
The increased phophiorous supply allows the
rapid development of large populallons oI marine


organisms such as plankton. As Ihes organisms
die and ettfle to the bottn, large amounts of or-
ganic material acumulate, mix with he sediments
and ae buried. It is thought that reactions within
the 5ed hents cause the Ilomalion oa the phs-
pate mineral rancl Ir it The subsequnil devel-
opment of aconmicaly ignuicat phosphale de-
posits results frDm the reworking of the phasphalim
sediments and the concentration of ih phosphate
by current and wave action.








FLORIDA GEOLOIGAL SURVEY


Figure 14, Hawthorn Group phosphatic sediment at or near the ourtme. Where this occui, the
pomlbility of radon problems ext.


Sediments of the Miocene-Pliocene age Haw-
thom Group contain large quantities of phosphale,
some of which occur in ecormically important
concenlrations. Curren( mining operations can be
seen in Polk, Hillsborough and Hardee counties
in central Florida and Hamlton County in north-
arn Florida. Much of 11he phosphate mined in
Florida Is processed to form various types of
fertilizers,


The Nogene phosphates in Florida contain vary-
Ing amounts c uranium Incorporated In the min-
eral francolite. The percentages of uranium
present range from hundredths to telhas of a per-
cent of the total mineral. The uranium Isolope ULP
is the most abundant lorm of uranium~ present in
Florida's phosphates. As Um decays radlo-
aelivsty. radon (RnP") eventually forms as one
part of the decay series. RaWon, a short-lived ra-
dioactive isotope. occurs a a gas which may


lawthorn Group sedimrnts
at or near eurfacs








SPECIAL PUBLICATION NO. 35


Ch~fa~a ~c 'ie An tloilne


OGf Trough


Jackson'lla Sasln


Apalacklcole +a
Embayme nt 9







Positive structural elements

Negalive structural elements

- .Linear axis of feature;
arrows point In deepening direction.


Central
Florida
P'/allorm


Figure 15. Malor geologle slruncural element of FIorka.


accumulate in buildings, causing potential health
problems. Wherever the Hawthon Group phas-
phalic sediments are present near the surface,
Ihe possibility of radon problems exist (Figure 14).

The early Cenozoic rocks of Florida are not flat-
lying bu form a seres of Jiig.s (plaitorms) an
lows (basins). These geological features are
known as structures. The later Cenozoic sedi-
ments are thinnest over the highs and ihlckesi In


the lows. Figure 15, a geologic structure map of
Florida, shows those features. The oldest sedi.
menia exposed in the state are exposed on the
rest oi the Ocala Platform, a major high failure
in weslcenlral Florida. Other prominent highs
include the Challahoochee Anticline, Sanfod
High, Brevard Platform and the St. Johns Plat-
form, The lows incude the Okeechobee Basin,
Oscsela Low, JackionvlNe Basin, the Gulf Trough
and the Apalachicola Embayment. A major,


Sun ford Hilgh


Bre Vat d
PFalIform









FLORIDA GEOLOGICAL SURVEY


IL
*iL '
'1'* . ... . . . . . . '1


i


I


fntergleciaI ShotsIfne
4150 teot above
present sea level)l


GWaclaf Sharelini

t300 fel be/ow presea


'II





I





I

I


Land area above 150 feet elevati


%* % 4%
ID o


Figure 1M Pleistocene shoreline kn Florda. Ilusirstlon by Prank R. RiL'rt.


actively suibiding basin, Ihe Gulf of Mexico Ba-
sin, lies west of the Florida Plalform. To Ihe east
of the peninsula Ile the Blake Plaleau Basin and
the Bahamas Basin.

QUATERNARY PERIOD

The Quaernary Period encompasses the last 1,8-
million years of geologic history, The Quatemary
Parlod Is made ol two geologic epochs, thi Plels.


tocene Epoch (1.B million to 10,000 years ago)
and Ihe Holocane Epoch (10,000 years ago to
the present) (Fgure 2). It was a time of world-
wide glacialions, widely fluctuating sea level,
unique animal populations, and the ermrgence
of man, Soas alternately flooded and retreated
from Ihe land area of Florida. Most lo the land-
orms charsalerlzlng Fl0rda's modem topogra-
phy. as well as th spring, lakes and rivers dot-
ting the state today formed during the Quaternary.


-~ ./


I
/
a
I


'I

a








SPECIAL PUBLICATION NC. 35


The Pleistocene Epoch, also Iknwn as the "lee
Age.' was punctuated by at least lour great glacial
periods. During each glaciation, huge ice sheets
formed and spread southward out of Canada, 0ov-
ering much of the northern United States- Sea wa-
ter provided Ihe primary source of water for the
expanding glacier. As the ic sheets enlarged. sea
level dropped as much as 400 feet below present
level, and the land area of FlorIda increased dta-
matcally (Figure 16). During peak gladal periods
when sea levI was lowest. Florida's Gulf of Mexico
coastline was probably stuated some 100 miles
west of its current position,

The Iresh-water table In Florida was probably
much lower than today during the Pleislocene sea
level low stands, The climate may have been sig-
nificantly drier as a result. Surface waler lealures
such as springs and lakes were les abundanl.
Only the hardiest of trees, such as oaks, and va-
rities of ragweed and dry-tolerant grasses would
have flourished. giving Pleistocene Fklride the
appearance 01 the modem African savannas.

The glaclatlons were interrupted by warmer in-
terglacial intervals, with earlh's climate wamnirng
considerably. As the climate wared, the glaciers
melted, raising sea level and flooding the Floilda
peninsula, At the peak interglacial stages, sea
level stood at least 100 to 150 leet above the
present level, and peninsular Florida probably
consisted of islands. Figure 1 illustrates the prob-
able Pleistocene shoreline positions in Florida
during the glacial and interglacial periods,

Many ot Florida's modern topographic features
ands surficial sedierme were created or depos-
lied during the various Pleistocene sea level high
stands. Waves and currents in these ancient seas
eroded the exposed lormatlons of previous ep-
ochs. reshaping the earlir landtorms and redls-
tribuling the eroded sediments over a wide area.
At the same time, rivers and longshore currents
transported trerwrndous quantities of sediment
Into Florida from the coastal plain surrounding the
Appalachian Mountains to the north. Much of the
quartz sand covering the slate today, as wall as
the heavy mineral deposits, trace their origin to
rocks of this once-great mountain chain,

The Pleistocene seas spread a blanket of sand
over the Illnestones underlying Florida's Gulf
coast, infilling the irregular rock surlace, forming
a relatively featureless sea bottom, During the


sea-level high stands, and as the seas retreated,
shore waves and near-shore currents eroded a
series of relict, coast-parallel scars and con.
saructed sand ridges spanning the stale. Many of
these features are formed on or carved out of
older geologic landorrms and are today stranded
many mlles inland, Nolable examples include the
Cody Scarp, the Trail Ridge. Brooksville Ridge
and Lake Wales Ridge (Figure 17), Some of Ihe
lowland valleys probably evolved largely from dis-
solullon and lowering of the underlying lime-
stones, and these areas may well have functioned
as Pleislocene lagoons or waterways bordering
the emergent ridges. The Eastern Valley probabMy
contalned such a waterway, situated between ihe
relict Atlantic Coastal Ridge on the east and the
higher ridges of the central peninula,

The karst nature of the Eocene, Oligocene and
Miocene limestones comprlsIng the foundation of
Florida influenced the development of Pleistocene
landlords. For millions of years, naturally acidle
rain and ground water flowed through these lime-
stones, dissolving a myriad o conduits and cav-
ems oul of the rock. In some cases, the cavems
collapsed, forming sinkholes. Karst aclivily more
than likely sporadically occurred through the
Pleistocene, forming new sinkholes and modify-
ing the existing landlords through collapse and
lowering of the limestone bedrock. In some ar-
eas large dissolution valleys formed, such as the
Western and Central Valleys of the central pen-
inasua, where dissolution processes lowered Ihe
valley floors relative to te surrounding highlands
(Figure 17}. Many of the larger Pleistocene skik-
holes and collapse depressions remain today as
lakes dotting the Florida landscape.

The unique geographic position of southernmost
Florida during the Plelstocene produced a terrain
slgnlficantly different from the rest l0 the penln.
sula. Here, carbonate sediments predominate,
and the sandy ridges of the central peninsula are
absent. South of approximately Palm Beach, the
marine conllnental slope approaches the edge of
the Florida peninsula. Most of ihe conlinenlal
quartz sands, moving southward with the coastal
currents during the Plelstocene, were funneled
offshore and lost down the continental slope. As
the glaciers melted and sea level rose, nutrienl-
rich water flooded the southern lip of Florida.
Calcium carbonate, in the Iorm of broken shell
fragments and chemically-precipltated panicles,
was the main source of sediments.








FLORIDA GEOLOGICAL SURVEY


srWEStEMN HIGHLANDS
, MAIIIARONNA LOWLANDS


Trail Ridge


40


FIgur 17. Major topography feature formed or shaped by Pkle ocene see. Illustration by Frank
R. Rupert,


The area ol Ue modern-day Evarglades was a
shallow marine bank, similar to the present
Bahama Banks. Carbonale sedlmenl bar, some
vegeiated by mangrove trees, protected the eot-
em edge al the bank rear Miami and to the oulh
along Ihe lower Florida Keys. Calcareous sedi-


ments and bryozoan aefs accumulated on the
shallow bank under very low wave energy onrdi-
tions. These sediments compacted and evenLu-
ally solidified to lorm the limestone that floors
the Evergladfe today. Diegolulion and crmenra-
tion by rainwater and acidic organic has since








SPECIAL PUBLICATION NO. 35


produced the Everglade's jagged, craggy rock
surface, As sea level climbed to Its present level
In the Lale Pieistocene and throughout the Ho-
locene, modem suriaee-waler drainage pattms
lorned, ultimately providing water for the irri
mense, southward-flowing "rkv of grass" which
would become the Everglsads.

Florida Bay, stranded as dry land during glacial
periods, was most likely a Pleistocene lagoon
during high stands ol sea level It was protected
Irom extensive wave activity on the south by a
chain of the then-living coral reefs of the Florida
Keys. Because of the protected, how-energy na-
ture of the south Florida area during the high
Plelstocene s.as, relict wave-formed features
such as bars, spits and beach ridges are rare.

Near the southern rim of the Florida Platform's
escarpment lies a fringeline of living and dead
coral reefs. The dead coral rels farm the islands
of the Florida Keys. The edge of the Florida Plat-
form, marked by the 300-reel depth contour line,
lies four-lo-elght miles south of the Keys. Today,
living coral reefs grow In the shallow waters sea-
ward of the Keys. This environment is ideal for
the growth ol coral: a shallow-water shell, sub-
tropical latitude and the warm nutlrent-rich Gull
Stream nearly.

The geoogical history of the Florida Keys began
about 1,8 million years ago, when a shallow sea
covered what Is now south Florda. From that time
to aboul 10,000 years ago, often called the Pleis-
tocene ice Ages, world sea levels underwent
many fluctuations of several hundred leet, both
above and below present se level, in response
Io lhe repealed growth and melting of the great
glaciers, Colonies ol coral became established
In the shallow sea along the rim o4 the broad, flat
Florida Platorm. The subtroplcal climate allowed
the o rals to grow rapidly and In great abundance,
forming reels. As sea levels Iluctuated, the cor-
ae main inalned footholds along the edge of the
plateau; their reefs grew upward when sea level
rose, and their colonies rereeated to lower depths
along the platform's rim when sea levels fell. Dur-
ing limes of rising see levels, dead reels provided
good foundations for new coral growth. In this
manner, during successive phases ot growth, the
Key Largo Limestone accumulated irom 75 to
200-feet thick in places. The Key Largo Limestone
is a white-to-lan limestone that is primarily the
skeletal remains of corals, with invertebrate


shells, marine plant and algal debris and lime-
sand. The last major drop in sea level exposed
the anoantl reefs, which are the present Keys,

During reef growth, carbonate sand banks peri-
odicelly accumulated behind the reef in environ-
ments similar to the Bahamas loday. One such
lime-sand bank covered the southwestern end of
the coral reefs and, when sea level hst dropped,
the exposed lime-sand or ooid bank formed the
Lower Keys. This white-lo-light tan granular rock,
the Miami Limestone. is composed of tiny, spherl-
cal soliths, lirre-sand and shbels O.ollhs may be
up to 2 mllllmeters in diameter and are made ol
concentric layers otfcalcum carbonate deposlled
around a nucleus of sand, shell, or olwr foreign
matter. Throughout the Lower Keys, the Miami
Limestone lies on tlo ol Me coralline Key Largo
limestone, and varies from a few leet up to 35
feet In thickness. The norihwest-southeast
aligned channels between islands of the Lower
Keys were cut In the broad, soft, oolite bank by
lidal currents, Then, as today, the tidal Currents
Ilowed rapidly into and oul of the shallow bay
behind the reefs, Keeping the channels scoured
clean. Exposures of the Key Largo Limeslone and
Miami Limestone can be seen in many places
along the Keys: In canal Wcu, at shorelines, and
in construction spoil piles.








FLORIDA GEOLOGICAL SURVEY


CHAPTER 4


GEOLOGY and MAN


TMi cl wlW hu Is *111iasw suwqi
of prtmWvs mw1 uing* lWIdsl ml-i-
ro fil roqura. Pp-Fn=UAThMAdW IInfid
tU. Hlsremwo Carmrxt. 112W, FOUS
phMra*.


Frank R. Ruprt PG 149
and
Kennelh M. Campbell PG 192

EARLY MAN AND HIS ENVIRONMENT

The Holocene Epoch began 10,000 years ago
during a slow warming of the Earth's climate. Sea
level climbed intermttently toward ils present level
Irom a glacial low about 18.000 years ago. As
the encroaching sea shrank the stale to its
present size. paleo-Indians spread throughout
Florida, flourishing on the abundant resources,
The first paleo-Indians probably migrated into the
slate Iron the continental mainland between
10,000 lo 12,000 years ago. The earliest docu-
mentalion ol man's presence In Florida comes
from Little Salt Spnng in Sarasota Counly. Paleo-
Indian skeletal remains from this site have been
dated at over 10,00 years old-

Sea level then was as much as 100 feel lower
than al present, and the land area of Florida was
much larger ihan it Is now. Upand Florida did not
have the lush tropical and subtropical environ-
ments we see today, Surface water was less
abundant and ground water was much lower than
at the present time. Permanent sources of fresh
water would have consisted of rivers and deep
sinkholes, such as Little Sail Spring, which inter-
sected the water table. Man's occupation of the
Interior of Florida was probably either of a sea-
sonal nature or limited to the vicinity of perma.
neni water sources. Approximately 9,500 years
belare present (BP) wetter conditions apparently


prevailld In Florida, making possible a gradual
increase in population and expansion into previ-
ously uninhabitated portions of Florida. Most early
tribes relied on hunting game animals and gath-
ering shellfish for food,

During the paleo-indian period (14.000 8,500
BP) and the Archaic period (8,500 3,000 BP)
which followed, exploitation of the geologic re-
sources of Florida was probably limited Io Ihe use
lo caves and sinks as water sources and pos-
sible shelter, and outcrops lo cherr lor the pro-
duction of projectlle points, scrapers and olher
tools. The next major advancement in the utiliza-
tion ol geologic resources was the manulacture
oI fired clay pottery. The earliest examples ol
pottery appear at various places in the state be-
tween 3,000 4,000 OP. The use of clay or mud
to seal vertical post-walled structures and Ihe use
of sandslane scrapers has also been docu-
manled.

Throughout much of the Neogene and Pleis-
tocene, Florida was hone to a diverse animal
population (Figures 18 to 21). Many unique and
now-exlinct species migrated into temperate
Florida to escape the cold and Ice of the huge
glaciers to the north. Fossil remains found today
in Neogene and Pleistocene deposits Include
mastodons, mmohs, black bears, giant sloths,
capybaras, beavers, lemmings, dire wolves.
horses, lapirs, camels, glyptodonts, Ilamas and
saber-tooth cats. Florida may have been a final
refuge lor many species as exinclion took its toll
on the once-diverse animal populations. Animals
such as the mastodon, mammoth, giant sloth and
saber-tooth cat disappeared forever.








SPECIAL PUBLICATION NO. 35


With the rising ea level during the Holocene
came a corresponding rise in Ihe sale's ground-
water lable. Most of Florida's springs, lakes and
spring-led river systems developed during the
Holocene Epoch. The rate of sea level rise slowed
about 3.500 years ago when sea level was five
Ieel below present level. Bythat time the beaches,


barrier islands and spNi characterizing Florida's
modem coastline had evolved. The complex geo-
logic pro eBs which shaped Florida into its
present orm continue loday, Florida continues to
evolve as the sea shapes the coasts and redis-
trfbules the sands and other sediments which are
to be the rocks o1 Iutu e epochs.


c7 '. ni h, i
Figure 1. Pleistocww mrimanh (Olsen, 1i59; *unr bPry Andrmw Janson).








FLORIDA GEOLOGICAL SURVEY


Flours 1. FRxid. ebmbrtlath Htow and Pi.istomoen ho. (Olso, 1959: drmv by Andw Janmon).


FIgure 20. Pleistocens mnmtdetac (OIs 1959; drawn by Andrew Jum.on).








SPECIAL PUBLICATION NO- 35


FIgure 21. "ant Sloth UMffwUh J~f and I'ptoacct (0l1n. 1Q59; drawn by Andrew Janson).


MODERN MAN


ECONOMIC MINERALS

Florida is not generally thought of as a mining
slate, however, it ranked 111th naionally in tolal
value of non-fuel minerals produced in 1990.
Phosphate rock, crushed stone and cement are
Ihe major commodities produced; bul clay, heavy
minerals, magnesium compounds, oil, natural
gas, peat and sand and gravel have also been
produced in recent years. In addition, sulfur is
produced as a byproduct of oil and gas produce.
tion while Iluorine and uranium are produced as
byproducts of phosphate production. Figure 22
shows the main areas of mineral production,

All mining in Florida is by opeh pit method. The
mineral commodity being mined is removed by
earthmroving equipment, dragline or floating
dredge (Figures 23 and 24}. The equipment used


depends on Ihe pit depth, water table conditions
and hardness of the material. Where the waier
able is localed below Ihe base of the pit, or where
conditions allow dawateding a pit by pumping,
mining can be conducted under dry conditions.
Where Ihe pit cannot be economically dewatered,
lloaling dredges or draglines are utilized to mine
below the water table. In limestone and dolomite
quarries, blasting is ollen required to break up
the rock prior Io mining.

Cement

Cement is produced by heating a finely ground
mixture of lime, silica alumina and iron oxide in
a rotary kiln, then pulverizing the clinker which is
formed. All of the raw materials can be found in
Florida. Cement production Is closely lied to cin*
struclion activity.








FLORIDA GEOLOGICAL SURVEY


Flour* 2L GenMloud map of mineral mining ease In FladdiL Compild by Sleven Spencor.


Clay


Clay is a general term lor common materials
which have a very fine particle size and which
exhibit the property of plasticity when wet Strictly
speaking, clay is both a size term and the name
of a group oi minerals. Clay-sized particles are
ihoie which are less than 0.000154 hncdes (1/
256 mm) in largest dimension. Clay minerals are
composed of hydrous aluminum or magnesium
silicates, which form, among others, the miner-
als kaollnite, smectite, illite, halloysile and
palygorskile. These minerals combine with a large


number of possible clay-sized impurities includ-
ing slica, iron oxides. carbonales, nmica. ldspar,
potassium, sodium and other Iors. Clay deposits
are lound In many parts of Florida, but only In
certain locations are they found wilh th proper
mineralogy, purity and volume necessary for crn-
mercial use. Clays that are presently mined In
Florida include luller's earth that is used as a
carrier to disperse Insecticides and as cat Iftter,
and kaolin and common days lor use as light-
weght aggregrale. cement Ingredients and con-
struction material.








SPECIAL PUBLICATION NO. 35


FOu" 23. Suotkan credgs -method of sand and gravl mlning. Fas photographs.


FIgure 24, Open pit lilmesone quarry. Bulldozer rip and stacks rock; the front-ad loade feeds
the portable crunmer; and the crushed rock is carried to the plant on the comeyo bel. FGS
photograph.








FLORIDA GEOLOGICAL SURVEY


Heavy Minerals

Heavy minerals are associated with essentially
all of the quartz sands and clayey sands In
Florida, but economically valuable concentrations
are known to occur only in limited areas, The ar-
eas which are of economic importance are the
Trail Ridge and Green Cove Springs deposits lo-
cated in northeast Florida, All of the commrrclally
valuable heavy-mineral deposits in Florida are
Inland Ifrm the present shoreline and are geneti-
caly associated wllh older, higher shore lines,
which were created during the Pleistocene. Heavy
minerals (minerals having a specific gravity
greater than 2.9) comprise approximately lour
percent of the fcnomic deposits. The lilanium
minerals, rulile, Ilmenite and leucoxene, make up
about 45 percent of the heavy-mineral Iracton.
SlaLurolile, zircon, kryanie, sillimanite, tourmanline,
spinel, topaz. corundum, monazite and others
make up Ihe remainder of the heavy-mineral
Iractkin.

Heavy minerals are mined by a floating suction
dredge equipped with a cutter head, similar to the
one shown in Figure 23. The heavy minerals are
removed from mIe quartz sand by running the
dredge's output through a seres of centrifugal,
magnetic and electrostatic separators.

The major use for the titanium-rich minerals (1-
menite, rtile and leucoxene) is to make white
titanium dioxide paint pigment and titanium alloys
used in military and aerospace Industries. Slau-
rolile is utilized as a source of iron and alumina
in cement production and as an abrasive. Zircon
is utilized lor laundry sands, refractories, ceram-
ics, abrasives, zirconium metal and chemical
manulacluring. Monazile is rich in the rare earth
elements cerium, yttrium, lanthanum and thorium.
Major uses of rare earth minerals Include cata-
lysts In petroleum refining, high emperaLure metal
alloys and optical glass.

Peal

Peal is formed when the rate of accumulation of
dead plant material exceeds its decay. Water-
logged sies such as esluaries, lagoons and
coastal marshes, large poorly drained areas such
as the Everglades, lake and river beds and sur-
rounding marshes and swamps, and seasonally
flooded depressions are common environments
In which peal forms in Flrida.


All peat presently mined in Florida is marketed
for horticultural purposes. Such a god conditioner
for lawns, nursBries and greenhouses. Extensive
farming in the Everglades is the major consump.
tive, non-extractive use ol peat in Florida. Even
though the peat Is not mechanically removed from
the sile by farming, the peal volume decreases
due to blochemicaf oxidation, compaction,
dessicalion, erosion, and fire.

Phosphate
Florlda has led the nation n phosphate produc-
lion for 95 yards, providing about 80 percent of
the US, produclton and approximately 25 per-
cent of the world production n recent years. Phos-
phate is found in sediments throughout much of
the peninsula of Florida, however, only two ar-
eas are currently economic to mine. The primary
mining area is the Central Florida Phosphate Dis-
trIct, located in Polk, Hillsborough, Manatte and
Hardee counties. The olher area in which mining
is occurring at the present time Is that portion Ol
the Norhern Phosphate District lying In Hamilton
and Columbia counties.

Approximately 90 percent i t1he phosphate mIned
in Florida Is used for agrcultural fertilizers. The
remainder is used in food preservalives, dyes,
hardeners for sleel, gasoline and oil additives,
toothpaste, plastics, optical glass, photographic
film, insecticides, soft drinks, fire fighting com.
pounds and in numerous other ways.

Two potential byproducts of phosphate produc-
tion are fluorine and uranium. Both are separated
anfer the phosphate rock has been digested into
phosphoric acid. Fluorine is used mostly to fluo-
ridate public water supplies, Uranium oxide ra-
covered from the phosphoric acid is used to pro-
duce uranium fuel lor nuclear power plants.

Sand and Gravel

Quartz sand is one of Florida's most abundant
natural resources. Almost al of Florida is blan-
keted by quartz sand. Very few areas within the
slate do not have deposMs of sand located within
reasonable hauling distance. Some construction
sand is mined in the panhandle, but the majority
of construncion sand is mined from the ridges of
the central peninsula region. Commercial quanti-
ties of gravel are presefl only in the westem pan-
handle and are associated wth river channel
deposits.








SPECIAL PUBLICATION NO. 35


Industrial sand accounts for less than 10 percent
of 1he sand mined in Florkda and Is used prima-
rly as giass or foundry sand or as abraslves.
Construction sand is utilized for concrete agwgr
gate, asphalt mixltres, roadbase material and
corntruelion fill,

Crushed Slone

Limeslonre and dolomiles ranging in age from
late Middle Eoone lo Plelstocene are presently
mined In Florida. Limestone and dolomite are
lound at or near the surface In several general
areas within the state: in the panhandle in
Holmes, Jackson and Washington counties; along
the west coast from Wakulla to Pasco
County and extending eastward Inlo Alachua,
Marion and Sumter counties; along the southwest
coast Irom Manatee to Collier County and In a
narrow band along the east coast Irom St. Johns
County south into Dade County and the Keys.


Mining methods vary depending on the position
of the water table and the hardness of the rock.
The easiest rrnling occurs In dry ptlL sof roak
conditions where bulldozers equipped with a claw
Can rip the rock loOse. Where pits are flooded,
draglin es ae utilized to remove the rOCk. Under
certain conduions both methods may be used in
mining the same pit, As rock hardness Increases,
blasting becomes necessary prior to mining. Af-
tar rock is rined it may be loaded directly for
transport to a processing plant, or It may be
crushed and slockplled on slse.

The major uses of crushed stone in Forida are
for roadbas material, concrete and asphalt, C-
ment manufacturing. fertlizer and soil condition-
ere and rip-rap for erosion control.








FLORIDA GEOLOGICAL SURVEY


CHAPTER 5


OIL and GAS


A pumping al will In
cullh F1InMM BW I%-
hmd Ciold. FOS tO-
r'h.


Jacqueline M. Lloyd PG 74
and
Ed Lane PG 141

Petroleum (rock-oi, from the Latin petra rock
or stone, and oleum oll) is widespread through-
out Ihe world. It may be a gas, liquid, semi-solid,
solid, or In more than one ol these states at a
single place. Any petroleum Is a complex cheml-
cal mixture oc hydrocarbons, which are com-
pounds composed mainly ol hydrogen and car-
bon, with smaller amounts of nitrogen, oxygen,
and sulfur as impurities.

Scientists think that petroleum ormaliion began
many millions of years ago, when lower forms of
plants and animals flourished in and near the
oceans, as they do today. When these organisms
died, their remains settled to the ocean bottoms
where they gradually were deeply buried in mud
and silt. Over eons of time, this abundant organic
matter was transformed into oil and natural gas
by high temperatures and pressures, decay, and
bacterial processes, in a natural pressure cooker.
At the same time, the enclosing sediments also
ware being transformed into consolidated rocks,
such as sandstone, shale or limestone. These
rocks, in which the oil was formed, are called
source rocks.

Contrary to popular belial, oil does not occur in
underground, cislern-like "pools" that can be
tapped and pumped dry. Pool is a term Ihai has
special meaning in the oil industry; it refers to an


economically produceable quantity of oil dis.
persed in rock wlthin the earth. Rock strala that
contain economically recoverable concentrations
of oil and gas are called rsetvoirs

In order for oil and gas to be concentrated in po-
rous reservoir rocks, natural traps, seals, or Cap
rocks must occur, in various Iorms. In south
Florida the oil traps are due to denser. less per-
meable rocks that overlie the oH Ields' reservoir
rocks. The traps in the north Florida panhandle
fields are due to very impermeeabl beds of anhy-
drite (evaporilic salls). faulting, and straligraphlc
traps.


During the course of oil and gas formation and
accumulation in reservoirs, some ol the original
sea water was displaced and gravity separated
the gas, oil, and water into layers. Figure 25 II-
lustrates this in principle, bui in reality the situa-
tion within a reservoir is much more complex. Oil
is only a small Iraction of the fluids in the pores
of a reservoir, but the discovery and recovery of
this small fraction is the basis of the oil industry
---and most ol the world's energy. Most of the
contained fluid is salt water, or brine, since Its
dissolved sail content may be higher than In sea
water. Almost all crude oil has som gas dissolved
in it under pressure. In srome cases, excess gas
forms a "gas-cap" above the oil zone. Figure 25
shows a small part of the rock that has in its p"re
quantities of oil, gas. and brIne, all under pres-
sure. Same pores may contain only oil, or only








SPECIAL PUBLICATION NO. 35


porouM ImIeatCmI
With all dontlng


brine
ii pores


oil with
)... .- ^ ^ /. -;,- ;:; : ,


Figure 25. Generalized ro se cion oil production and bna Injection In outh Florida ol tla.
Curvature of beds ls greatty exlragrld.The mnkroscople view of 1th porous reservoir rook, on h*e
right, show how oil and walm, though immlsclble, co-exlit, coming and filling the voids. Produc-
ing wells bring up a mixture of al, brine, and dissolved gas, which re separated near the wellhead
(Lane, 186b).


gas, or only brine, or mixtures of all. Some of Ihe
oil is coated on the rock, while some is suspended
in the brine. II a well were to penetrate this zone,
the pressure would try to drive lth oil, gas, and
brine out of the rock end into the we-l Nol all of
the gas and liquids would be driven out, however,
no smaller how great the driving pressure. Much
of Ihe oil wo id still remain In the rock due to cap-
illary and molecular attraction between the rock
and oil. Several techniques have been devised
lo Increase the yield of oil from Ir$UErvoirs, such
as water, steam, or gas injection, and even ignit-
ing some ol the oil, bul reovery usually is rela.
lively low; a recovery of 30 to 40 percent of Ihe
in-place oil is considered good.


There are two o produclng areas in Florida. One
is In south Florida, with 14 elds, and the other is
in the western panhandle, with seven fields. The
south Florida fields are lIcated in Lee, Hendry.
Collier, and Dade counties {Figure 26a). Florida's
first oilfield, the Sunnlland field, in Collier County,
was discovered In 1943 (Table 1). it has since
produced over 18 million barrels of oil Subse-
qusntly, 13 mor field discoveries were found to
lie along tie northwest-southeaaa trend through
Lee, Hendry, Colier. and Dade counties. Although
these fields are relatively small, production Is slg.
nlficanL Together, the three Feda fields (West
Felda. MId-Felda. and Sunoo Felda) In Hendry
County have produced over 54 million barrels of
oil (Table 1).









FLORIDA GEOLOGICAL SURVEY


:-X AKA-Irn


0 ACTIVE OIL FIELD


Ie' V


-It U
w sr


4X.Mt


Figure 2an. South Fimahda all Slod Iocatkon map aftar Lloyd, 113).


South Florida fields produce oil from small "patch
reefs" within the Lower Cretaceous Sunnliand
Formation {Figure 26b), from between 11,500 and
12,000 feet below land surface {Table 1). The
ilrala of rock from which oil and gas can be pro-
duced to a well is called the pay zone, Surlnlland
pay ones vary from aboul 5 to 30-leet thick.

The depositional environment during the Lower
Cretaceous In south Florida was one of a shal-
low sea with a very slowly subsiding sea boltom-
The ime Interval was characterized by nuner-
ous iransgresiort and regressions of Ihe sea
over the land, which created the carbonate-
evaporite sequence of geologic rarmations shown
on Figure 21b. The Sunniland "raels are not true
patch reefs but were calized mounds of marine
animals and debris on the sea floor. The primary
mound-builders loud In the Sunniland limestone
were rudistids, oyster-llke mollusks Ihat existed
only during the Cretaceous. They lived In great


profusion and were widely distributed in clear,
shallow Cretacoa seas- Olher marine life found
in he Sunniland patch reels, or mounds, Included
calcareous algae, seaweed, foramrnifera, and
gastropods, such as snails.

Foramirilera, usually quite small, are single-
culled animals with external skeletons or tests.
Because al Iheir Incalculable nwmbMers n Ihe seas,
their tests and remains cani represent significant
amounts of organic debris on the ocean bottom.
PeaNts and other organic debris also accumulated
In Ihese mounds. The remains of the rudistids,
other marine lifa and debrls were deposited on
the sea floor, forming porous limestones. Poros-
ity within the limestone was enhanced over suc-
ceedlng sons by the gradual transformtalon ol
limestone to dolomite, which resulted In goo res-
ervoir rocks to hold the oil.


i .1

5








SPECIAL PUBLICATION NO. 35


LIMESTONE


i


CLASTICS


pra
fc^
Fsa I
NZL-4


BROW
DDLGMTE
ZONE


BASAl
CLASTICS


DOLQOIITE


ANHYORITE


FGS080491


Figure 2b. Oenerolized stratigraphic column for south Florda, Upper Jurassic to Lower Crta-
eoua Oil producUton is from the upper 100 ifl of lhe Sunnillu Fonnmtion (fter Lloyd, 199).











FLORIDA GEOC.OGICAL SURVEY


Tabe 1. FlIrOda oil Ield dtoovory well data (Tootle 1-92, in Uoyd 1993).

DISCOVERY UATE FEW CouT~Y APRPO

BELOW
SURFACCE

%-L&43 urtrla d Ccali~e 11 ,Bw6

z.i-54 40-PNI~e B&Mi 11,5o

7-22-64 Sunow FoLda HunIFy 11.485

W1-2-65anlt Fekia "W&Y 11 A7$

3-SO-69 Lake Tfdtd CL r1 j"7

&15-70 joy Garnvainoal 1 8M

12-19-71 RM. CAnnel Sank Poon 15-W39o


Msci4oclc Cf..k

Da4m Ilwi'd

Swninalw

L~hk9J1 Prri;

Swpetwawn CreeI

Bmader wlulmd

FMi-Feida

Re000on Poirot

Pappor 1I4anmcck

TownwDO C&Wl

Bluff Sprirv4



UCLWYL~R

Ccbdwata CoeA

McDavId


Friendly

Lao

Saria Rmsa



Hwdry
Collier
Ocrbor


Colier

Kwry



Cdlktr

Gantm Rosa:

sanoFig

LzemiaiI


1 S235



11,651



14,511




11 ,89I




11,462



11.~50

14.475

11886
1.6w


NAME OF
PROD LAW M
FORIMATION





Surn'i~aa-,d




Sunrilardd
$iw~and




Norphta

Smackmw


SunnMand
Surw ilmid




Surdibnd
Suarti~mid

Sirmrdvl





Sunnilard

Smackauv




Smankmwr


snwekoww

IWneAa


CL PROOUCTION
1I4ROUGH 8gi,
X1000 BARRELS


ia,449

33





as
11,594

41 ,slo

278

972,072

4.706


55- 5

10905

a5

5.272

14

2

1.a66

6,567

0

472

242

Ta3

241

27



&529.17


The porous irmeranest and dolomrtos grade lal- Surkniland oil. The Sunniland Formation, Wiere-
erally Into ron-poarus, chalky lime mudetones, fore, appears to include its Own oil source rocks
These dense limestones form a barrier I0 Oil ml- and some of Is own seals. Addltboial seals are
gration, thus trapping the oil In the more porous provided by the evaporites 04 be overlylng Lake
rocks. Research Indicates thal the dense mud- Trafford Formation,
clones are probably the source rocks for Ihe


214472

12-5-72

11-14-73

713-74

4-22-77

a-11~-7

W-13-77

6-20-78

9-28-78





11-1045

2-19-8a

6-4439
1&14-





SPECIAL PUBLICATION NO. 35


R33W R232V :IV R30V ;29W


0 ACT:VE OIL F:ELD
o .\1 ACTIVE OIL FIELD


I,
LIC;-II


Ir .


c L -TET I


7-"i Cw


Figure 27a. North Floride oil field location map (after Uoyd, 193).


Production In the weslern panhandle began with
the discovery of Jay liad in June 1970 (Figure
27a, and Table 1). Jay field is tthe largest oil field
discovered in North America mince the discovery
on the Alaskan North Slope of the giant Pfudhaoe
Bay field In 18 8. Since then, an addlltonal six oil
lields have been discovered in the western pan-
handle of Florida (Figure 27a). These leWs' pay
zones are from about 14,500 to 15,800 feet be-
low land surface and vary in thickness from about
5 to 259 leet.

North Florida has dominated Florida oil produc-
tion sinoe the discovery ol Jay field. North Florida
oil fields account for B3 percent of the state's cu-
mulatlve production through January 1988. Jay
field alone is responsible for 71 percent ol the
stale's cumulative production.

Jay field is located within the "Jay trend" of
Escambia and Santa Rolaa counties in Florida,
and Escambla County, Alabama. The Jay trend


fields produce oil from Juraseic-age Smackover
Formalon carbonates and Norphlet Sandstone
sands. In Florida, the Jay trend fields Include Jay,
Mt. Carmel. Coldwater Creek, and Blackjack
Creek. The Jay trend fields In Florida and Ala-
bama are associated with a normal lault complex
which rims the Gulf Coast and Is believed to ex-
tend to the south-southwest Into the Gulf of
Mexico.

The other panhandle oil fields are Bluff Springs,
McLellan. Sweetweter Creek, and McDavid. Bluff
Springs field probably formed as the result of a
structure formed by movement of the underlying
Louann Salt (Figure 27b). McLeilan and
Sweetwatr Creek are probably associated wlth
small salt structures or with the slrallgraphic
pinchout of the Smackover Formation.

Production lor all of the panhandle oil elds. ex-
cept ML Carmel, is from Jurasslc-age Smaci~ver
dolomites and limestone. M. Carmel field


Li R "W-F


f0 H.ES





FLORIDA GEOLOGICAL SURVEY


SANDSTONE


Li


LIMESTONE


CLASTICS


SILTSTONE


DOLOMITE


IA A A i
+L
*
*J.


SHALE


MN.


ANHYDRITE


CONGLOMERATE


SALT


FGS070491



Figure 17b Genwmiltd mtratgaphic cokam or north Florid, Middle Jurasic to Lowr Cr-
ceoau. Oil production Is ftm intervalt In the Snmackov Formtlon and the Nopht SwKndtofw
(after Uyd. Il3).


I.






SPECIAL PUBLICATION NO. 35


YEAR


Flgum 29. Graph of hlhorl trend ol oil and gms production
pUuxdi 19 M).


produces from both the Smackover and the un-
derlying Jurakic-age Norphlet Sandstone {Fig-
ure 27b). Although a mixture of carboriats and
classes can be found within the Smackover, in
the western panhandle producing area. it s1 al-
most purely a sequence of dolomiles and lime-
stones. The underlying Norpjhet Sandslone is
primarily an arkosic sandstone. The Norphlel is
underlaln by the Louann Salt. The Smackover
Formation is overlain by the Buckner Member
of the Haynesille Forrmatlon, The Buckner is


from Florida flilds, 1943 to 1991


composed primarily of anhydrite, and other
evaporites, and forms the seal 10 some of the
Smackover producing zones,

Figure 28 shows the historical trend of oM and
gas production from Florida fields. The bell-
shapes of the curves indicate that production of
both commoditles peaked about 1979, and It has
been dealinlng sharply since. This Irend will con-
tlnue unless significant discoveries are made in
the lulure.






FLORIDA GEOLOGICAL SURVEY


A"iump t r." r viburami frumk pmrducrs iwlr rmminumwlly lm wlmL. wwrum
for oil explrorMion by poudirng Ihe guro with thO I rg pltb In hi atw.
FBS phctlgrnph.





SPECIAL PUBLICATION NO. 35


CHAPTER 6


WATER RESOURCES


Porty and mn4e0Ilt 4W whom by wm inapbas of well
Garled gramhw *Wklr sugh w sw "A" Is Wwen &M pmr
imabb wkh dmrh 6eW Md Inerouieagrlud vokis, mrlau w&
bibo move limtThe pwoor WW In "OH Is h mf erIm m* toW&w
BI rlRw dim to eMtw aihMt el fine .wlslrtl hn pores, such as
d"y ILuMG. 1111)6


Kenneth M. Campbell PG 192
and
Ed Lane PG 141

The continuous movement of water in all its
phases on the Earth's surface is called the hy-
drologic cycle (Figure 29), The hydrologic cycle
begins wlth the evaporation of sea water by the
sun. Evaporated water is Iransported through the
atmosphere by convective currents. Condensa-
tion of water vapor forms clouds, which produce
precipitation as rain, snow, or hail. Once precipi-
tation reaches the land surface it takes one of
two paths depending on terrain elope, soil per-
mebillty (or lack of permeability], soil moisture
Content and vegetation cover. Steep slopes, low
permeability and soil saturation increases the
quantity of water which runs off into lakes, sireams
and rivers. Conversely, shallow slopes, perme-
able surflcial and near-surface materials and veg-
elalive cover increase the quality of water which
infiltrales into the surlicial material. Some of the
precipitation returns to the almosphere because
eo evaporation from land and open bodies of wa-
ter, such as lakes and streams, and by itrnspi-
ratton of plants. Some of the water which Infil-
Irates into the ground flows to lower levels Ino
streams and lakes. Some of the ground water
recharges the regional aquifer system. Depend-
ing on local geologic conditions and the relative


levels of the water, water in lakes and streams
may either recharge he aquiler or the aquifer may
discharge into the lakes and streams as springs.
Eventually the waler is retumed to the ocean.

The majority of Ihe potable water used in Florida
is obtained from subsurface rock units called aqui-
fers (Figure 30). An aquifer must be both porous
and permeable (i.e.. contain interconnected
pores), so thai water may move freely within t,.

The Cenozoic sediments In Florida form the sev-
eral ground-water aquifer systems that provide
the vast majority ao the slate's waler supWies. The
Paleogene carbonale rocks, for the most part,
make up the Floridan aquifer system, which is one
of the world's most productive aquifers. A vari-
able series of highly permeable rocks separated
by low permeability rocks comprise the Floridan
aquiler system. The base of the aquifer occurs
where the evaporite minerals 1il the pores in the
Paleocene to Early Eocene rocks. The early Neo-
gene sllciclastlc sediments form the top of the
aquifer system by providing a relatively Imperme-
able cap. Where these sediments are present,
the Floridan aquifer system is under confined
condllions and acts as an artesian aquifer, In ar-
eas where the overlying confining beds are ab-
sent, the system is unconfined.














































Figure 2. Hydrologic cycal: the orwatnt movwemewrnt ground wmtar, urfno, and otmnophwric
wetsr .The diagram la high slnmplftd (uno, 19t6b).





SPECIAL PUBLICATION NO. 35


In southern Florida, an extremely permeable and
poroue zone occurs in the lower part of the
Floridan aquifer system. This zone, referred to
as the "Boulder Zone," l thought to be the result
of dissolution of the carbonate rocks by ground
water. Cavities formed by the dissolutlon are In-
terconnected allowing vast amounts of water to
flow easily through this zone. The term 'Soulder
Zone arises from the drilling ciaracteristics of
this unit. When drilling operations encounter this
zone, pieces of rock ("bouldte") break from the
calling of the cavities, fan to the caviles' floors
and, when the dril bit encounters them on the
boltom, cause the bit to bounce around. Imped-
ing drilling. This zone contains highly salne wa-
ter and is often used for the subsurface dleposal
of waste water.

The Intermediate aquiler system or kitermedlaie
confining unit, where they occur, lie above and
are separated from the Floridan aquifer system
by beds having lower permeability, such as clay,
which retard the exchange of water between the


two units. Otlen the intermediate aquifer system
con lsts of interbedded carbonate and elastic
rocks, some of which are permeable enough to
provide water to wells. Water within lhis system
is under confine4d conditions The base of the
Internmdlate aqulfr system (or Intermediate con-
fining unit) Is the same as the top ao the Florldan
aquifer system (Figure 30).

The surfldal aquiler system Is at or near land
surface and i generally composed ol loose sedi
ment., such as sand or gravel. The surf Ilal aqul-
fw system contailr the water table,. and water
Is generally unconfined.

Potable water sources are a vitally important natu-
ral resource and ar extremely vulnerable to pol-
luhion due to the shallow and unconfined nature
of many of the aquifers in the state. Even the
confined aquifers at deeper depths are vulner-
able due to recharge from point source situations,
such as poorly constructed wells and from sink-
holes which breach conilning layers.











PANHANDLE FLER:DA


SYSTEM SERIES LITHOSrTArT]GRAPHIC JNIT .


'JUATiENAkY


TER-'ARY


fOL OCENE



PLE:STOCE[NE



PL;DaEHE


lIDGENF


XL .nrr['N


D4IFFERENTIATEN
PLE[STECENE4-HELDCENE
SEIIMEfNT



EITRFELLE FnPMATICN
H[ICDSUKEE FOBrMATION
CDARSE CL.ASTICS
- - - -
ALM' BLUFF GRDJP
PENSACL.A CLAY
]NTRACOASTAL Fr)NAT1ON
HAVTHEON CRIP
BEIE EREEK L[CIEs~NL
SIIAnRs FDRmIATHElN
CHiATANXDCHEE FORIMT[E h

CEICKASAVHARY LJMES TfEE
S'AUANNEE L3MESTI'NE
MnW]ANP4A LI]MENTODE
BULATLINA CLAY


OCALA LIMESTIE
EEOCENF
CLALBOIR GR;LP
UNDIFFERENTIATEI SLDJIMNTS


,,ALOCENE


Sh9i' L JL I
uI 1- L


LI#)[FFERENTIATED P


UNDI FERENTIAT


SURICRAL
AUItR
A~ur[1
SYvSIe


INTERMDIRTE

UNIT


FLORInhh
FB'CQR
s Y3-g


sI -,LD-RiIW
CONF[NEhtu


*ALEUCENE LNtTT

ED
-1
T ~ I -


NORTH FLURIDA
I


L[THOSTRATIGRAPHEC
UNI-


UiIDIFFERCNTEATED
PLEISTD'KEC-HO-DCET'E
SED ENT '
M[DCCSUKEE FORIATON
CYPReSSHEAD FI3R1AHlll
NAS"HU FnArt9rTI



HAVr-Mh GR.IjP

STATENVNLLE FUiRMAT
co VsA4A'CiE FPM
ARKS*iEAD FARMATI N
PENhEY FARMS FOM1fATJlM
sl MA(5 ORstKMTMI


SUWVAtNEE LIIESTD4E


OCULA L[EN.TENE
AVON P(AR FDPrMTl0t
EDLBSAR FDRMAT]EN



CtLun KCTS rr TRIATrnN

bND[FFERFNTIAT'r


1DROSTRATI-
r [MAN ULIT





SUR JICAL
ML]FER
SYSTEM


TERDI1ATE
AUJ]FER
SYSTEM OR








STFLi[D

UYSTHE


SUB-FLdRLIDAN,
EDWINrIN --
UIT


SOUTH FLORIDA

LITHESTA GRAPHIC IIBDROSTRATI-
UNIT GRMHC UNIT

UNDIFERENTrATE
PLEISTDC3ttE-MaDTNE :PRF
1SEDIENTS
A4JIFER
MHe LllCSTttE A9
KEY LAMGr LShME51I TEE
ANASTASlA FrMRATEOIN
F3RT TIttP r i D-, ,N



TANLAMi FMrATIDN
TAINTERtMPDIT




~BrA.RS
HALVTHRN GROUP SYSTEM O
P cACE RIVER nFiRTIDN
N3HC VALLLE wIeHM ULNIT
UA=rMA FORMATION


t*Ii-N(ICATECE
MEMBERS



SLWnAHf? LtE9TCNEA
f-FLOrAN
_auir(R
SYSTSE

LOCALA LIICSTEM4



AltUC PEFRTAltNGT


U -----------T-D C FM T
eE~~~rL4VW .~v ^T] "C-URI
urrilUFlI T[PtWW WCO


gure 30. Corrmelain chart showing the rltflolnhlps of ibgr hydrogeological units (mqutm
and confining units) to major straligraphlc unit in FRorid.Thl- l a gsnmalaed camposh ind ll
units may not be preit at y givn locatllon (Scott et a., 1991; modfied from: Sutheltern
Geologlcal Society, 196).





SPECIAL PUBLICATION NO. 35


CHAPTER 7


GEOLOGIC HAZARDS


11MMiaom beome a goolooo E *aar4 *too thmy Oor i
ag" mWi wwtiacfta Pas phomarsok


ED LANE PG 141
and
KENNETH M. CAMPBELL PG 192
KARST TERRAIN

Much of Florida Is karst terrain. Kare terrain is
the generic term Ior landfonrm that have been
shaped by dissolution of the underlying carbon-
ate rocks. Kars terrains have drainage syelerns
distinctly different frm the usual surface drain-
age systems Ihat have connected streams, riv-
ers, and lakes, Karat drainage is characterized
by lsnkholes. springs, caves, disappearing
streams, and underground drainage channels.
The genesis o karst Involves Ihe development of
underground drainage systems. Karat processes
lend to be secretive and imperceptible because
most development occurs underground over long
periods of time. The results of these persistent
processes will be manifested, sooner r later, in
the subsidence of surlicial sediments to form
swals, the formation of a new sinkhole, a sud-
den Influx of muddy waler in a water-well after a
heavy rain or some other karst phenomenon that
may disturb or disrupt man's aclivlties. Figures
31a to 31 d illustrate the evolution of karst terrain,
as described below.

Chemical weathering is the predominant erosive
process that forms karat lerraln. Chemical weath-
ering of limestone removes rock-mass through
solution activity. As rain falls through the atrro-
sphere, sorry carbon dioxide arid nitrogen gases


dissolve in it, forming a weak acidic solution.
When the water comes Into contact with decay-
ing organic matter In the soil, It becomes more
acidic, Upon contact with Ilmestone, a chemical
reaction takes place thal dissolves some of the
rock. All rock and minerals are soluble In water
to some extent, but limestone is especially sus-
ceplible to dissolution by acidic water, Lime-
stones, by nature, tend to be fractured, jointed,
laminated, and have units oa differing texture, all
characteristics which, from the standpoint of per-
colating ground waler, are potential zones of
weakness. These zones of weakness in the lime-
stone are avenues of allack thai, given time, the
acidic waters will enlarge and extend. Given geo-
logic time, conduits will permeate tht rock that
allow water to flow relatively unimpeded for long
distances.

During the chemical process of dissolving the
limestone, the waler takes into solution some Of
the minerals. The walker containing the dissolved
minerals moves to some poinl of discharge, which
may be a spring, a stream bed, the ocean, or a
well.

Removal la the rock, with the continuing forma-
lion or enlargement of cavilies, can uttimalely lead
to the collapse of overlying rocks or sediments,
sometimes revealing the cavity In the rock. More
often, though, debris or water covers lhe entrance
o1 subterranean drainage, Partial subsidence of
Ihe overburden into cavities will form sales at
Ihe surface, producing undulating topography. By





FLORIDA GEOLOGICAL SURVEY


Figur 31.. Relalvely young kaM iandsep. @hoawing urmdeuly ing I to beds aWd sandy ,eW,
burden wftI norrowl, Watgrated surface drelnl Some okitlon Imaturue ere Just booimning 0c
dveiop in Wo lmslon.v (Lane, I Mb.



N c
Falling rain absorbs gase, to become weakly eilxec.


SWYALE Percolating ground waler Infiltrates
IInx ltcwne, dlasoiuIng some and
carrying It away In salutlon.
I 9jinds.in

011yan~
4, _J i~niP ciQdi round water


frretures. boddingp piano$ .~ -


Figurio 31b. DW1.11 of Figure 311a sheuring wulvy w sg. of kmt formation. Lhknswto Is reltvly
competent and uwrod'd. Chemicl wuthierlng Is Just beginning, wIfh 1I0* Inrnul circuluatin of
wawl through te Ihneallone. Swlles, formin Indpilurd sinkhleu, at to onoanbat rciurg e (Lane,
1mbft





SPECIAL PUBLICATION NO. 35


Figur 31 c. Advanced karat landscape. Original aurfac has been lowered by solullon and erosion.
Ony mjor streiam How In surface channels and they may cae to flow in dry awesome Some
brteam may disappear down walow holes and resurge to thu s urrfe their dowrtream. Swake
and shlnkhole capture most of the surface wawe and shuni It to dth underground drain sysalm.
Cavenous zones are well developed In the imesuone (Lane, 1996b).


CAVERNOUS UNDERWATER SPRING'


Figur 31d. Detail of Figure 31c showing advanced stag of kart forwmation Lnmetone has wo
developed Interconmcted passage that form an underground dranage system, which captWue
much or 1 of prior urfaca dralnage Overburden h. collapsed Into cavlties orming kwae or
sinkhole. Cawv may form. Land surlce has been lowered due to loss of sand into the Umestone'i
voids Wakulla Spring, Slver Sprirng, and Rainbow Springs are jus three example of cavrnous
underwater springs that occur In Florid (Lane, 1986b).





FLORIDA GEDLOGICAL SURVEY


this slow, persistent process of dissolution o4 Iime-
stone and subsequent collapse of overburden, te
land is worn down to form a karIl terrain.

At some point In this process of dissolution of
underground rocks, a normal surface drainage
system will begin to be transformed into a dry or
disappearing stream system. Continuing disso-
lullin of the limestone will create more rwales
and sinkholes, which will divert more of the sur-
face water into the underground drainage. Even-
tually, all of the surface d rinage may be diverted
underground, leaving dry stream channel that
flow only during floods, or disappearing streams
that flow down swallow holes (sinkholes in stream
beds) and reappear at distant points to flow a
springs or resurgent streams.

Inherent in the formation 01 kart terrain Is the
lowering of land surface on a regional scale, In
contrast to the very localized lowering a sink-
hole. Flegonal lowering of the land surface
takes place Ihrough the cumulative effects of
thousands of individual, localized events and
through the continual removal of carbonate rock
by dissolulion.

FLOODING

Flood prone areas In Florida are maso9iated pri-
marily with either low-lying coastal areas or with
Inland rivrs and lakes. Coaslal areas, including
the barrier Islands and estuarine aeas which are
so highly developed in Florida are subject lo flood-
ing. Severe flooding poblems can result from the
storm surge developed as hurricanes or "north-
easlers' approach the shoreline. Storm surge is
created as water is pushed ahead ol the storm
and piled up against the shoreline, Normal tidal
action is added to the storm surge, which can
produce waves several feel above normal.

Away from the coastline. Ilooding Is associated
wilh river and stream floodplins, lake margins,
low-lying, and poorly drained areas such as the
Everglades. The rnaonty of stream or river-re-
lated flooding problems can be avoided by sim-
ply not building on floodplalns. Heavy rainfall
events in iat lying, poorly-drainrd areas can re-
sult in flooding because the water drains on at
such a slow rate. Extensive areas of Florida have
been subjected to major drainage enhancing
projects. Typically Ihese projects include river


channelization, drainage dhlching and storm
water Impoundments. These projects often pro-
vide flood relief but the environment may suffer.

UNSTABLE SOILS

The presence of unstable or plastic geologic
materials In the near-surface can create founda-
tion problems in construction projects. Organic
materials, such as peat or muck deposits, do not
have the strength to support structures. Some
days shrink and well upon drying or weling,
which can stress buildings' foundations to Ihe
poinl of failure. These material must generally
be removed or addressed n the design of road-
beds or foundations.

Figures 32 and 33 show a landslide Ihat flowed
into a nearby stream channel. Heavy local rains
weakened and lubricated the unconsolidated
sediments of the hillside causing sudden failure.

EARTHQUAKES

Historically, Florida has had very lillle earthquake
activity since the earliest recorded tremor, re-
ported to have been fell at St. Augustine on Oo-
tober 29, 1727. Since then, about 30 tremors have
been reported throughOUl Florlda (Table 2). The
strongeal tremors that have been felt Over the
widest areas of the stale were associated wllh
the great earthquake of August 31, 1886, in
Charleston, South Carolina, about 180 miles
northeast of Jacksonville. Tremors from this
earthquake were felt all over north Florida;
church bells rang in St. Augustine, severe
shocks were fell along the east coast, and trem-
Ors were felt in Tampa. Jackkaoville lelt more
aftershocks Iron that quake during September
and November 1886.

Two geological event cause earthquakes: active
lalts and volcanic eruptions. Florida has no vol-
canoes and no doaumanled active laulta, so there
is very little chance of an earthquake originating
In the stale. Probably al of the approArnately 30
historical tremors reported were the result of
earthquakes thai occurred oulslde Florida. In
addition to the historically active lault near
Charleslon, South Carolina, te Caribbean area
Is also seismically active, and several *quSakes
lell In Florida appear ao be the result of tremors
near some of the Islands.





SPECIAL PUBLICATION NO. 35


Figure 32. Ahil phoograph of the Pt larnidslde, April 2, 194B, in Gadaden County (T3N, RSW, sM
32de). Photograph by Tallshassee Akbraft Corpration (Rupart, 1990).


Figur 33. Photograph looking southwsl at the scarp of the Ptt landslide. Note people Ma upper
rlghL Photograph by R0.O.Vernon, AprH 5 1948 (Rupert; 1990)





FLORIDA GEOLOGICAL SURVEY


There has been recent evidence that some vry
localized rumblings or "earth trermrs are, in fact,
caused by cold air masses aseBDated with fron-
tal weather systems thal have high altitude winds
from the southwesL Some of these weather sys-
tern are known to have layers of air wthch have
been stratified due to temporalure difference,.
Creating, In effect ~tunn.els" o air of differing dlen
cities. In addition, there Is clrcumstanlial avidance
that sonic wooms from mWitary airplanes trying
over the Gulf of Mexico could be 'focused
onshore" through such temperatura-stratilied
layers of air,
Florida is classified as a stable geological area.
This means that, with respect to probable dem-
age Irom the largest expected distant earthquake,
some armnr may experience tremors, with wnly
minor damage, such as broken windows or glass-
ware. Severe weather events, such as hurricanes
and tornadoes, pose tremendously greater
threats to Florida than do earthquakes.
The severity of an earthquake is expressed by
two different methods: the Rfc ver Scale and the
Modifid MrMefl Inftensity Scale. The magnitude
of an earthquake-expressed by the Richter
Scale--s related to the amount of seismic en-
orgy released by the earthquake. The Rlchter
Scale is based on the amplllude of earthquake
waves recorded by s4smarnomters. Rlchler values
are given as whole numbers and decimals, such
as 5.1 or 7.2, with larger earthquakes assigned
larger numbers. The Richter Scale Is not used to
assess damage; the Modifled Morcall Inlensity
Scale was devised to do this,


I08


The inftnstyol an marlhquke-expressed by tie
Modlfied Me ralll intensity Scale (usually written
as MM-Is based on observed effects of ground
shaking an people, buildings, and natural fea-
tures. Values of b* range Irom MM I to MM XII.
MM I Is died as: not faith eicps by a very few
people under especaly favorable co~dfirw. A
mid-range value of MM VI is: damage sight, f~e
by all, many fIrghtenwd; some heavy furniture
moved; a few Wistances of lalfn plaster. A value
of MM XII represents catastrophic destruction,
and is defined as: damage loa., obfa;ets throw
into te air; fina of sight and level ar distored.
While the MM scale Is an arbllrary ranking based
on personal observations. It does provide a mean-
intful measure of severity to a non-selenrtist, be-
cause it refers to effects actually experienced.
The energy released by an earthquake travels as
seismic waves through the earth and along Ihe
surface. Seismic waves ot energy passing
through roPk strata cause alternate expansion
and compression of the rocks. One result o Ithis
is that the seismic waves can cause the water
level to flucluale in a cased well, and a water level
recorder installed on the well can, under special
conditions, act as a crude seismograph. As the
water level changes a record is preserved of the
earthquake, as on a real seismogram. The Florida
Geological Survey has an Instrumented obser-
valion water well which is sensitive to some of
the larger earthquakes. II has recorded several
of Ihe world's major earthquakes (Figures 34 and
35). Figure 36 shows the effect he great 1964
Alaskan earthquake had on another instrumented
observaliob well thai was located north of Lake
Butler, Union County. Florida.


normal water level Irlae






TIME


Figure 34. The Columblun rthqual* c Dc mbr 1 1,979, Rdhl)r magnhude 7.9, killed St Ieet
600 people. It caused the water Ievl In the Florida Goological Survey's obervalton we$ to fluetuat
10.8 Inchiu (Lane, 1991),


_ __~_NNNPNNNNftWNW





SPECIAL PUBLICATION NO, 3


Figure 35. A magnitude 7.7 quake hit t omtl part of lhe main PhlIppine Island of Luzon, north of
Manil, on July 16, 1 88 I caused about 1.8 Inchs of water wl hclnge in the Florda Geologcall
Survey' obrvaitlon well. Thb t h first kown earthquake reoorad by thi well -hat ocurred
such a great distance fom F loritd,, 13,000 miles acrow the PcUlfic OceanThis demonetrnte
the awesomn amounts of energy related by manar earthquake. After amling hIlrwy around
the world, this quake's stlmic waves till had enough energy to caui nerly two nchem of water
klvl luctuabon In the Florldan aquller ysterm (Lane, lg91).

Table 2. A ~Isting o4 known earthquakes and "trreom" felt in Florida, froun 1727 through 1991,
with estimated eplenter and intenltles. Compiled from Cmpbell (1943) and counts from
local newspaper.

October 29, 1727: Unofficial sources reported a severe quake, ol intensily MM VI (Modified Mercalli
Vi), in SI. Augustine, but the original record has not been located. New England had a severe shock
about 10:40 a-.m on this date, and a quake was reported on the island of Mariniq ue, in the Caribbean,
on the same day.

February 8, 1780: Pensacola felt a Iremor described as "mld,"

May 8, 1781: Pensacola suff red a "sEverei treirnr that shook ammunltion racks Irom barrack walls,
leavaed houses, but no fatalities.

February B, 1 B43 Earthquake in West Indies, felt in Unlled States, Inlersity unknown.

January 12. 1879: Earthquake fel through north and central Florda bounded by a ine drawn from Fort
Myers to Daytona on the south, to a line drawn Irom TIalahassee to Savannah, Georgia, on the north,
an area ol about 25,000 square mlles. Intensity MM VI near Gainesvllle.

January 22-23, 1880: Earthquake in Cuba of Intensity MM VII, aboul 120 miles east of Havana. It was
also lell in Florida.

January 27, 1 5BO' Several shocks of Intensity MM VII to MM VIII were felt in Key West resulting from a
disastrous earthquake at Vuela Abajo, about 80 miles west of Havana, Cuba.

August 31, 1886: The great earthquake In Chareston. South Carolina, MM X, This quake was fet all
over north Florida, with an estimated Inltenslly of MM V MM VI. Church bells rang In St. Auguslkne, and
severe shocks were felt along the east coast Quake effects were felt In Tampa.

Seplember 1-9, 1888: Jacksonville lelt more aftershocks of Intensity aboul MM IV from the Charleston
quake.


earthquake shock -
1.8"




normal water level track T

TIME


_____ __





FLORIDA GEOLOGICAL SURVEY


November 5, 180I: Jacksonville felt another aftershock from the Charleston quake.

Juno 20, 1893' Jacrsonville felt a tremor at 10:07 p.m. of estimated intensity MM IV.

October 31, 1D&I: US. Coast & Geodetic Survey recorded a local shock of MM V at Jackuowille.

January 23, 1903 Shock of intensity MM VI felt at Savannah, and effects also felt In north Forida.

June 12, 1912: StrOng shock of unknown Intenilty felt at Savannah; also felt in Florida,

June 20, 1912: Shock of intensity MM V felt at Savannah; probably associated with the above quake of
June 12. It was also felt In north Florida.

1930: (Exact date unknown) An earth trenor was fel over a wide area In omntral Florida near LaBelle,
Fort Myers and Marco Island. Thought lo be from an earltquake, but some persons believed it waa
tremendous exploslns, though no exploalions were known to have been detonated. Eslimaled inten-
sily at Marco Island was MM V.

November 13, 1 3I Two short tremors were felt at Palatka in the early morning. The aacond shock
was fell at St. Augustine and on nearby Anastasia Island, Estimated intenslly al Palalka was MM IV or
MM V.

January 19, 1942: Several shocks 1ell on south comas ol Florida, with some shocks fell near Lake
OkeechObee and In Ihe Fort Myers area. Esimated intensity was about MM IV.

January 5, 1945: About 10 a.m. windows shook violently in the DeLand courthouse, Volusa County.

December 22, 1945: hock felt In the Miami Beach Hollywood area at 11:25 a.m. Intensity was MM I
to MM IIL

November 8, 194B: A sudden jar, accompanied by sounds like distant explosions, rattled doors and
windows on Captiva Island, west ol Fort Myrs.

November 18, 1952; Windows and doors were rallied by a slightly remor at Oulnay, about 20 miles
northwest ol Tallahassee.

March 26, 1953: Two shocks estimated as MM IV were lell in the Orlando area.

October 27. 1973: Shock felt in central east coastal area of Seminole, Volusia, Orange and Brevard
counties, at 1:21 a.m.. maximum intensity MM V.

December 4, 1975: Shock felt In Daytona and Orlando areas at 6:57 a.m,. maximum intensity MM IV.

January 13, 1978: Two shocks reported by residents in eastern part of Polk County, south of Haines
Clty. Tremors were about one minute apart and each lasted about 15 seconds, shakig doors and
rattling windows. The tremors occurred between 4:10 and 4:20 p.m No injuries or damage were re-
ported.

November 13, 197: Tremor felt in parts of northwest Fllda, near Lale City. Seisric station al Ameriks,
Georgia, estimated It originated in the Allanlic Ocean.

1978 through January 1991: No tremors reported by Gainesville seismographic stalton,





SPECIAL PUBLICATION NO. 35


4


over 10 feel,

off recorder scale


- main *arthquakle hook


aftershocks






normal water level Irae.


I TIME
Flgua 34 .Th, Good Friday erthquake th& lruc Alaska on March 27,1964, regslered 8.4 on bh
ReihtMr alel, and wen the lsges Instrumenrtlly record 6arttquake everm to strike the North
Amerfle conwrkm t. It causNd this watr level reconler's pen to go off-ece, In both directions, a
waoer hlvel fluctuaton of over 10 Iest In th wrl. Th mejor ~hak waid tw h afttwsrooks caused ihb
water wlevl to flutuat for more Iham two hoou.Th.l rncrd toi from a monitor well locatd north of
Lake Buler, Union County Florida (Lme, 1991),


~





FLORIDA GEOLOGICAL SURVEY


GLOBAL WARMING AND SEA LEVEL RISE

The shoreline is a dynarmi system. Sand Is cor-
stanlly being moved around by wind and waves.
Shorelines. islands, spits. bars, and dunes
change shape, move, grow or diminish in size or
even disappear as part of the dynamic natural
process.

Adjustment of the system to changing ,natural
conditions. In tihe form ol erosion and deposllbon,
does not have a good or bad connotation until
man places structures and fixed property lines
along the shoreline. Florida has almost 9,000
miles of detailed tidal shorellne, exposed 1o el-
Ihr the Atlantic Ocean or the ulf of Mexico. The
majority of this shoreline Is eroding or elable; only
a small portion is growing,

Large porions of the Florida coastline are dvel
oped. Development ranges from weekend cab-
Ins to ocean-fronl cities such as Maml. There is
Intense pressure from property owners and city
officials to protect property. Unfortunately,
prolecilon ot improperly placed structures is
expensive, temporary and all too often only ac-
compl.shed at the expense o the beach system.

Devices such as sea walls and grolna may pro-
tect structures, but do so at the expense of the
beach. They also typically multiple as adjacent
property owners undertake similar projects to
protect their property. Beach renourlshmrent is an
expensive. temporary solution, but it has the ad-
vanlage of not increasing eroslon II the sand
sources are located properly, and it preserves the
beach both as a recreational area and as a source
of sand lor the transport system.

Evidearc is acurmulating that indicates a strand
of global climatic warming, which may be the pre.
lude to sea level rise along most of the world's
coast lines. The geological record, from the Pre-
caibrlan to the present, shows that the Earth's
climate has undergone many fluctualions from
warrnr-to-colder-to-warmer. Some ei the warm-
lo-cold dcinale changes created extensive gla-
clatlons accompanied by drops In sea level, as
great quantities of water were removed frmm the
world's oceans. A return to warmer climates
melted the glaciers, replenishing the oceens, and
caused sea level to rlse.


The present warming may be another of Earth's
natural climatic oscillations. Considerable evi.
dence, however, suggests that human activities
and Industrial pollutants are changing the com-
position of the Earth's atmosphere, thereby ac-
celeraling or triggering the warming. The m cha-
nriu thought to be responsible for this warming
Is the greenhouse eflec The greenhouse elect
is caused by small amounts o carbon dioxkie,
methane, and several other trace gases in the
atmosphere. These gases absorb the sun's radl-
ant heat and retain It In the atmosphere, raising
the temperature, as In a greenhouse- Increasing
amounts of these gases are being injected Into
the atmosphere, raising Its temperature.

Because Florida has such an extended coastline,
and since so many major population centers are
near the coast, any rise in $ea level poses a
threat. Figure 37 shows the changes In Florida if
ees level rose 15 and 25 feet above present level.
Great changes would occur In south Florida, ex-
lending north of Lake Okeendobee. As sea level
gradually rises, the higher ridges will become is-
lands, and the Keys, the Everglades. and Big
Cypress Swamp regions will be under a shallow
sea. The Atlantic and Gulf coastlines will Invade
many miles inland, creating successive strings of
barrier islands, such as now exisi along the
present coasts. The mouths of rivers wll retreat
miles inland, creating shallow bays and estuar-
ies. With a rise of 25 feet in sea level some of
these new bays will nearly cut the panhandle into
several segments. Figure 16 shows the effects
of a 150-leet rise In sea level, which occurred dur-
ing the PleIstocene.






SPECIAL PUBLICATION NO. 35


Coastal changes around Florida If sea wlv should drse


SUnder water Iaflr 15-fetF rigr In r0 lev*.

lUder watfr after 25-le rit le In sea lv4l


Figure 37-. 0outal chwig"u wound Florida If lSWI ei should rfse 15 and 25 feet &bow* preasnt.


-,r






FLORIDA GEOLOGICAL SURVEY


CHAPTER 8


WASTE DISPOSAL


Kenneth M. Campbell PG 192


Waste disposal in Florida falls mainly Into two
categories: landfills and deep well injection. The
vast majority of domestic and municipal waste
generated In Florida is disposed of In landfills.
The primary environmental consideration in sil-
ing landfills is Isolation ol the landfill Irom adja-
cent aqullers and surface waters. Several dec-
ades ago, early landlilling practices left much to
be desired, In terms of adequate protection of
water resources (Figure 38). Some of the rain that
falls on a landfill site percolates through the soil
cover, leaching contaminants from the waste
which then may pollute adjacent water resources,
Modern landfills now often use impermeable


J

Drinuel mwl In be.uwm of uluiMble luI *tonU wowm dl-
r*:c* lr oquwr (LAr wmd Hokwmldrm 1M1


liners and drainage systems to intercept leachate
for subsequent treatment (Figures 30 and 40).
Ideally, landfill sites should be placed where the
aquifers are protected by natural Impermeable
confining beds and away from areas which re-
charge the aquilers. Recycling and Incineration
will probably account for signlllcant quantities of
solid waste disposal In the future.
Deep well injection is used to dispose of indus-
Irlal waste water and treated water from sewage
treatment plants at selected sites throughout the
state. These materials ar' injected into sallne
ground water at depths below the base of the
potable aquifer and in rock units that are sepa.
rated from the aquifers by thick conllning beds.


Figure 3& The old way of garbage and trash dispoal: unsegregated refuse dumped In an unlined
pt, compacted. covered with a raw inches of dirt, and forgotten. Photograph by Ed Lanr, 1968.






SPECIAL PUBLICATION NO. 35


Figure 3B. A new cel being prepared at the Marion County landfill, showing plastic iner on left and
rear wala. The lner has been covered whh sand on the lher two walls for protecting. Note the six
leachsa collellon ppes on the let wall and the 30,00B -alaln Ileacha holding tank In the left
background (from Lane and Hoenmline, 1991).


FI SHE;, CLOSE. CELL -
'00


TO
HOLDI 1
TAL,IK


LEACHATE COLLECTION Pir'I;
7.N _0P 0' LIN R


7
WALLS OF CELL



100-MIL


SAN4D
-7- --- -CAY-7--- - -

SAND


* -- _- C L A TY - . . . .


. OCALA GROUP LIMESTONE
(FLORIOAN AQUIFER SYSTEM)


WIWiTi1R 61115
AROUNlD L.'NDFLL


Figure 40. Gwerawllfd cross a~etion of new call th* Marion County andlll (from Lan and
Hoerstne, 1991).


-"






FLORIDA GEOLOGICAL SURVEY


CHAPTER 9


ENVIRONMENTAL GEOLOGY
AND FLORIDA'S FUTURE


Ed Lane PG 141

Geology documents fho past,
monitors Me present,
and predicts the ufuue.

The truth of that elatement Is attested to by the
preceding text, which has covered past, present,
and some future aspects of Florida's geological
history Knowledge of Florida's geological history
has a great deal of pertinence in land use plan-
ning, source management, and conservation
practices. Crucial to the decision-making pro-
cesses in these matters is knowledge about min-
eral and water resources, landforms, geological
hazards and waste disposal. Ill-advised choices
about any of these matters can have dire, and
usually long-term consequences for citizens of a
nation, state, region, or city.

Florda's environment and geology are intimately
related. The state's rocks and minerals have,
through the processes of weathering, erosion and
deposition, formed the soils and landforms that
constlltue the present environment which sup.
ports the plants and animals that inhabit Florida.

An understanding of Florida's environment has
become a major focal point of public policy. In
part, this interest and concern has developed
through increased public awareness ol the fragil-
ity and Importance of the environment, Its rela-
tionship to the state's economy, and Its eflecl on


R.Fpannibli ue of Firlda'l nabtul rowwo request
woelty toa coaltwthou.t harmful Kpfla on.Thee beeh
hoim rlak dMetuwtn bewoaoe they wwe Ibul tno ftr oni
iw tOft*. Phooqraph by Ed Lan.


the quality of life and heath, Also, Florida's phe-
nominal population growth, as many as 900 new
residents each day, is projected to make it the
country's third most populous slate by the year
2000. Such rapid growth places unusual stresses
on the environment due to the demands of en-
ergy, construction, transportation, water supplies,
and waule disposal.

Florida's environment is directly Influenced by its
surface and near-surface geology, which can be
characterized as a relatively thin, suriiclal veneer
ol sand, silt, and clayey sand overlying exlen.
sive limestone and sand and gravel aquifer sys.
teams. Karst phenomena, ublquitous throughout
Florida, are Intimately related to local gelogy and
water resources. Karstification provides easy, and
rapid, access to an aquifer by rainwater and any
entrained contaminants.

Urbanization increases the types and amounts of
contaminants to an aquifer. Pavements and roofs
concentrate runoff so that the natural filtering
action of oil is bypassed, Addlifonal potential
threats to ground-waler quality due to urbaniza-
tion include improperly installed septic tanks and
drain fields, leaking petroleum storage tanks,
drainage wells, and Improper landfilling prices,
A knowledge of local and regional geology is us-
sential in planning for environmental saleguards
while wisely managing, developing, and conserv-
ing Florida's natural resources.





SPECIAL PUBLICATION NO. 35


REFERENCES


Campbell, R. B., 1 43, Earthquakes in Florida: Proceedings of the Florida Academy of Sclences, vol, ,
no. 1, Marc, p. 1-4.

Dielz. R, $- and Holden, J. C.. 1972 The Breakup of Parngeea; i Conlinents Adrift, W.H. Freeman & Co.,
172 p.

Haq, B. U., Hardenbol, J., and Vail, P. R.. 1987, Chronology of fluctuating sea levels since the Triassic:
Science, v. 235. no, 4793, p. 1156-1167.

Lane, E., 1991, Eari quakos and sslmlo history of Florida; FIorlda Geological Survey Open File
Report 40, 11 p. (revisIon of FGS Information Circular 93),

_, 196a. Geology ol the state parks in the Florida Keys: FIrida Geological Survey Leaflet 14, 28 p.

S19M6b. Karst In Florida: Florida Gololgical Survey Special Publication 29, 100 p.

and Hoensilne, R. W,, 1991, Environmeilal 0g01ogy and hydrology of the Ocal a rea, Forida: Florida
Geological Survey Special Publication 31, 71 p.

Lloyd, J. M., 1993, 1990 and 1991 Petroleum production and exploration including Florida petroleum
reserve esllnates by Charles H, Too0le: Florida Geological Survey Inlormation Circular No.
108. 31 p.

Nelson, K, D., McBride, J. H., Arnow, J, A,, Oliver, J, E., Browvn L. D., and Kaufman. S., 19M. New
COCORP profilng In the southeastern U.S-, Part II: Brunwick and asa coast magnetic anoma-
lies, opening of the north-certral Atlantic Ocean: Geology. v. 13, p. 718-721,

OIeI, 8, J,, 1959. Fossil mammals o0 Florida: Florida Geological Survey Special Publicalion 6, 75 p.

Rupert. F. R,, 1989. A guide to geologic and paleontologlc siles in Florida: Florida Geological Survey
Map Series 125.

,1990. Geology of GadsOe Counly, Floida: Florida Geological Survey Bulletin 62, 61 p.

Scotl, T M,, Lloyd, J, M,, Maddox, G, (editors), 1991, Florida's ground water quality monitorwig program,
hydrogeological framework: Florida Geologial Survey Special Publication No. 32, 07 p.

Souheaslem Geological Society. Ad Hoc Committee on Florida Hydroslratigraphic Unit Definillon,
1986, Hydrogeological units ol Florida: Florida Geological Survey Special Publcation 28, 8 p.

Thlackray, J., 1980, The age of the Earth: British Institute of Geological Sciences, London, England.





FLORIDA GEOLOGICAL SURVEY


GLOSSARY OF SELECTED OEOLOGCAL TERMS

aquHfor a zorn below the Earth's surface capable ot producing water in useful quarAlles, as from
a well.

basalt a dark-colored, One-grained Igneous rock formed From molten rock thal flowed onto the
surface of the Earth,

basement rocks or basemni refers to very deep, ancient rocks that underie the continents arnd
oceans.

basin a large area that sank faster than surrounding areas during geologic time and In which a
greater thickness of sediments was deposited.

brachlopoda marine Invertebrate animals In which tiIe sof parts are enclosed by two shells,
called valves.

bryozom Iiny marine anirnmas that build colonies with their calcareous shells.

elcaroua conlalning or primarily mad of the mineral calcite (calcium carbonale, CaCO).

confined aqulfer a zone of subsurface water-bearing rocks that contain water under pressure due
to zones above and below it having low psrmeablily, which restrict the flow of water into and
out of it, Also called an artesian aquifer,

coral tiny, bottom-dwelling, marine animals that secrele external skeletons of calcium carbonate
(calcite). The colonies they create with their skeletons can make norrrmous roaf-complexes,
such as the Forida Keys, the Australian Great Barrier Reel and many coral Islands In the
Pacific Ocean,

crinold a marine animal consisting of a Cup or "head' conlalinig the vital organs, numerous radiat-
Ing arms, an elongale, jointed slem, and a root-like attachment to Ihe sea bollom while the
body, stem and arms float.

era a large division of geologic lime consisting of two or more geologic periods.

erosion the natural processes of weathering, disintegration, dissolving, and removal and trans-
portallaon of rock and earth material, mainly by water and wind, as well as by ice,

exotic train a terrain that has undergne signdlcant motion or travel with respect to the stable
continent to which t is accreted. Florida could be considered an exotic terrain with respect
to the North American continent, since it is thought to have once been part of northwest-
ern Africa.

fault a break in the Earth's rocks along which there has been displacement of the rocks. Displace-
ment may vary from inches to miles,

floodptaln land next to a river that Is flooded during high-water flow.

foraminifera liny, orw-celled, mostly marine animals whlch secrete shells of calcium carbonate or
build them of cemented sand grains. They occur in such quantities that their losmil shells
compose almost all of certain limestone rocks in Florida and olher places In the world,





SPECIAL PUBLICATION NO. 35


fossil remains or traces of prehinslric animals or plants. The most common types consist of bones,
carbon films, petrified wood, shells. molds. or casts,

granted a light-colored. coarse-gralned igwous rock formed from magma that cooed below Earth's
surface.

gron a shore-protectlon structure that projects away from shore, usuaRy made of rocks, wood piling
or sheet metal,

karat a type of terrain characterized by sinkholes, caves, disappearing streams, springs, rolling
topography and underground drainage systems. Such terrain Is created by ground water dis-
solving limestone.

lava molten rock trat tflow onto thr surface from a volcano or fissure.

magma molten rock generated within the Earth.

marine rfe re to sea water, to sediments deposited In sea water, or to animals that live In the sea, as
opposed 0o ireth water.

mollusks invertebrale animals, including a variety of marine, fresh-water and terrestrial snails; clams,
oysters, mussels, scallops: squids, octopuses, pearly nautilus, as well as the many extinct
varieties.

palaontoiogy the science that deals with the lile of past geological ages. based on the study of
lossils.

period one unit of geologic time into which earth history is divided. Period is a subdivislon of an era,

permeablity the measure ol a porous material's ability to allow fluids to pass through its pores.

potable water water of drinkable quality.

potentiomeltc surface an imaginary surface defined by the level to which water in an aquiler would
rise in a well due to the natural pressure in the rocks.

precipitalt the process whereby solids are left behind when liquids evaporate. For example, vast
deposits of salt were created when ancient seas evaporated.

rtit or drifting refers to the breaking apart of plates.

allne salty; sea water or water nearly as sally.

sandstone a type of rock made ol sand grains cemenled together.

selsmic pertaining to earth vibrations or to equipment or methods of creating earth vibralions, such
as earthquakes or exploding dynamite.

shale a rock made ol clay particles cemented together and which usually can be made to split into
thin slabs.

allicllastlc pertaining to classic, noncarbonale rocks that are almost exclusively silicon-bearing.
either as liorrn of quartz or as silicates, Examples of Florida siliciclasTics are loose quartz
sands, sills, or clays.

63





FLORIDA GEOLOGICAL SURVEY


sl1ston. a rock made of ill-slze particles cemented together.

ainkhole a funnel-shaped depression in the land surface that connects wilt a subterranean passage
created by solution. May also lorm by collapse of a cavem roof. Aso called doit'i

spreading center a fissure separating plates, created when the plates move apart

subduction the geologic process whereby one conlinenal plate slides under another and is gradu-
ally consumed In the Earth's Intrior.

utlure a line or mark ol splllinig open or ol joining together, such as where parts of two continental
masses collide and merge.

awale a shallow depression in the land's surface which may be filled with water,

toetonic pertaining lo the rock structures and external forms resulting from the deformation ol the
earth's crust.

test a hard covering or supporting structure of some Invertebrate animals; a shell.

transpiration part lo the Ille process of plants by which waler vapo escapes forn leaves and enters
the atmosphere.

unconformity a surface of erosion or non-deposition, usually the former, that separates younger
strata from older rocks. It represents a missing span of lime Irom the rock record.

water table the upper surface of the zone of saturation under uncon ined conditions; water in the
rocks Is at atmospheric pressure.