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 Title Page
 Front Matter
 Preface
 Table of Contents
 List of Illustrations
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 Index
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Scenery of Florida Interpreted by a Geologist ( FGS: Bulletin 17 )
CITATION SEARCH THUMBNAILS PAGE IMAGE ZOOMABLE
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Permanent Link: http://ufdc.ufl.edu/UF00000145/00001
 Material Information
Title: Scenery of Florida Interpreted by a Geologist ( FGS: Bulletin 17 )
Series Title: ( FGS: Bulletin 17 )
Physical Description: Book
Language: English
Creator: Cooke, C. Wythe
Publication Date: 1939
Copyright Date: 1939
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Source Institution: University of Florida
Holding Location: University of Florida
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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.
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ltuf - AFH8937
alephbibnum - 001093349
System ID: UF00000145:00001

Table of Contents
    Front Cover
        Front cover 1
    Title Page
        Page 1
    Front Matter
        Page 2
        Page 3
        Page 4
    Preface
        Page 5
        Page 6
    Table of Contents
        Page 7
        Page 8
    List of Illustrations
        Page 9
        Page 10
    Main
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    Index
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    Back Cover
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    Spine
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Full Text






rt:









STATE OF FLORIDA

DEPARTMENT OF CONSERVATION

R. L DOWLING, Supervisor
HERMAN GUNTER, Geolbgist




GEOLOGICAL BULLETIN NO. 17




SCENERY OF FLORIDA

Interpreted by a Geologist





By
C. WYTHE COKE, Ph. D.
Geologist, U. S. Geological Survey




Prepared in cooperation with the U. S. Geological Survey




Published for
THE STATE GEOLOGICAL SURVEY
TALLAHASSEE, 1939





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Published July 31, 1939


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LETTER OF TRANSMITTAL







HONORABLE R. L. DOWLING,
Supervisor of Conservation.
SIR:

I have the honor to transmit a report entitled: "Scenery of Florida,
Interpreted by a Geologist," by Dr. C. Wythe Cooke of the United States
Geological Survey. This has been prepared in cooperation with the U. S.
Geological Survey and it will, I am confident, be well received. It embraces
a popular subject, one that has intrigued not only our own citizens but the
thousands of visitors as well. It will form Geological Bulletin No. 17 in our
series of publications.
With appreciation for the interest you have shown in the work of the
Geological Survey, I am


Very respectfully,
HERMAN GUNTER, Geologist,
Assistant Supervisor,
State Board of Conservation.


Tallahassee, Florida
June 14, 1939.


109940










PREFACE



A landscape conveys different impressions to different observers.
The artist sees form and color and the play of light and shadow.
The farmer notices the growing crops and estimates the yield. The
speeding motorist watches mainly the condition of the highway and
the traffic on it. The engineer calculates the possibilities' for power
development or irrigation. The geologist sees in the landscape the
result of the natural forces of erosion or accretion acting on rocks of
various degrees of hardness, cohesion, and solubility. He can visualize
an ocean where now is desert, or, in imagination, roll back the waves
and convert the bottom of the sea into dry land. Each observer inter-
prets the landscape according to his own interests and individual ex-
perience. Fortunate is he whose broad perspective permits him to
view the world from many different angles, who can look on it with
the eyes of both artist and artizan, for he can see more than'either
one alone.
This book is written for two audiences; for the layman, who can
be expected to have little familiarity with the specialized geological
vocabulary, and for the geomorphologist, whose writings reek with
technical terms. It is hoped that the compromise adopted will be
intelligible to both; that what is lost in precision will be gained in
lucidity.
The reader will notice one dominant motif running through the
work--the influence of fluctuations of sea level on the development of
the land of Florida. Ancient fluctuations of sea level are mainly
responsible for the variations in the composition of the rocks that make
up the Floridian Plateau, and the more recent fluctuations that oc--
curred during the Great Ice Age played a conspicuous part in shaping
its surface.

Washington, D. C. C. W. C.
May 1939











CONTENTS

Page
P reface ............ ................ ..... ........ ............ .. ... .. ......... 5
Dimensions of Florida ............-.............-..........---....... 11
Floridian Plateau ...................... ....... ....... .................... 13
Coastal Lowlands .......... ................... .................. 15
Western Highlands ......................... -.-........ -------- 16
Marianna Lowlands ........... ....--..... --.... .--....... ---.. 18
Tallahassee Hills ... ................. ........... ....... .......... ....--- ..... 20
Central Highlands .... .......................... .... ........... ..... 21
Geologic composition ....... ....... .................. ...... ........... 23
Geologic formations ......................... ... ............. 24
Factors shaping Florida .............. ....... ................. 330
Erosion by running water .................... -.... ....... -------....... .. 30
Effects of solution .....---..- ...-. ... ...............---.... .. ... --- .--- 31
Work of waves, winds, and currents ...............-...- ................--- 32
Fluctuations of sea level .....................-.... ...... .. ... ......... 33
Marine terraces ................. ........ ----......- ..--------- 33
Brandywine terrace ..............-....... ...... ---- --...--- .......... 40
Coharie terrace ...................... .... ....... ... .... ..-- ---- 41
Sunderland terrace .......--................. .... -- ....- ................... 41
Trail Ridge ..................... ..... --. ... ..- ... ........ .. 42
Baywood Promontory ...................................... .................... 44
Other areas of Sunderland terrace ...... .............. ..... ...... .. .......... 46
W icomico terrace ... -........-........- ... ..-............ .. .. ... ...... ... 46
Penholoway terrace .......... ................... .... ............- 48
Talbot terrace ............ .......-------- .......... . ...........49
Pamlico terrace ................ ...........................--.---- 51
Big Cypress Swamp ...... ..........--........ .. .....-------... ..- 55
The Everglades ......... .............. . ........ ........ ..........-- .... .. 55
Rim of the Everglades ........................ .. ......... .............. 56
Florida Keys ..........................- ................~-- .....-- 57
Other areas of Pamlico terrace .............................. --... ........ 58
Coast line ............. ...... ............... ................... 59
General features ......................................-------- ..................... 59
Peculiarities of the East Coast, the West Coast, and the tip of the
Peninsula ................................ ........ ....... ..... 59
Islands and beaches ................... -- -----------..... ..... ....... 61
East Coast ...............--....... ...-..... .. ....... .. -------- ........ 61
Florida Keys .................. .---..--............... 68
Marquesas .........----- ............-- ........ --.-.----- 70
Dry Tortugas ....... ................. ......... ......--.. .... ...... 72
Tip of the Peninsula .............................------....... 72
W est Coast ....... ............ ........ ............ .........-- 73
Lagoons and bays .................----.-........... ... -- 80
Harbors ........................ ................................... 85
Rainfall .......................... ..-....... --.... .... ......... 86
Ground waters ...........-...........-- ... .... .... -- ......... 87






CONTENTS-(Continued)
Page
Springs .....- ---.........---.. ... .....------........--....... ---- -- ----------------- 88
Rainbow Springs ...........-----.......----.........-...- .----- 92
Weekiwachee Spring ........- ..-----...---. --...-----..---..----... .... 93
Salt Spring ................................... ... ......... ............ ..... 90
Silver Springs .................................... ....------.. -....-.. ..------ 90
Spring at H udson ............ ......................... .. ......... ... .... .................. 93
H om osassa Spring ........ ...... ........... ...... .. .... .........- ..........--.. 94
Crystal River .---.........................-.... .... -....-..-.....---. .----- ......---- ......--- ..... 94
Springs near the Gulf Coast ..............---..- --.......-- .....-......-- ..... 94
Juniper Spring ..................--.............------------------........................ ..................--..... 94
Silver Glen Spring .............. ......... ...... ........................ 95
A alexander Spring .......................... ...... ...... ............. .........--- .... 9
Orange Spring .............. .................................---------- -........ 96
Green Cove Springs ............ -..... ........... ..................... .................. 97
White Springs .....---.......--................................-.................. 97
Itchatucknee Spring --- --.............--.................... .................... 97
W akulla Spring ........................................ ........................... ... ..................... 99
Sulphur springs ......... ...................................... ............. ...... 99
O their springs ...................... ........ ............. .. .................. ................... 99
Lakes ...........--------...........-- ........................ .............................-......... ......................... 100
Lake Okeechobee ................... .. ................................................... 101
Other original depressions ...-------.......... -- ....................... .......... 101
Other lakes in the Peninsula .............---................ ....... ................ 102
Lakes in the Tallahassee Hills ............-.........-.............. ............ 103
Lakes In W est Florida ................... ....................................... .................. 104
Stream s ............................................... .... ............. ................... 105
Streams of West Florida --...... -----------............. ....----................................... 105
Streams of Northern Florida ............ ........... ........................ 106
Suwannee River ............................ ................................................................. 106
W ithlacoochee River ............................................................................... 107
Other West Coast Streams -.....................------ -................... 107
St. Johns River ..................................... .................. .................. 108
Oklaw aha River ............ ........ ..................................................................... 109
Sinks ..........--.......--- ......- ----------------...... .... ......................... 110
Caverns .... ...... ...................... ......................... ................ ..... 110
Natural bridges .........----..------...... ...------------............. --111








ILLUSTRATIONS


Page
Figure 1.-Photograph of relief model of part of North America, includ-
ing the Floridian Plateau ........................ .... ... ........................... 12
Figure 2.-Profile across the Floridian Plateau along latitude 28 N. Ver-
tical exaggeration about 139 times ..--..---................................... 13
Figure 3.-Topographic divisions of Florida. Maps of the areas enclosed
by dotted lines have been published by the U. S. Geological Survey .... 14
'Figure 4.-An emerged sea bottom near White City, Gulf County. Part
of the Pamlico terrace ................................ .... ............................................ 15
Figure 5.-A scene in the Western Highlands. Compass Lake, Jackson
County ................ .............. .. ...................................................... .. 16
Figure 6.-A scene in the Marianna Lowlands south of Greenwood, Jackson
County. The clumps of trees are in sinks formed by the solution of
lim stone under ground .......................... ........... ........................... ........- ..... 19
Figure 7.-A scene in the Marianna Lowlands between Greenwood and Bas-
com, Jackson County ................. ....-. ..-..... ......... ........ ......................... 19
Figure 8.-A scene in the Tallahassee Hills on U. S. 90 four miles east of
the O chlockonee R iver ........................... ........ .................. ... ................. 20
Figure 9.-Live oaks in the Tallahassee Hills four miles east of the Och-
lockonee R iver ......... .. ......-- .... .. .........- -. .... ......... ................................ 21
Figure 10.-A lake in the Central Highlands 5 miles west of Interlachen .... 22
Figure 11.-A quarry in an emerged coral reef (Key Largo Limestone) at
Key Largo .. ... ...... ............----..............--- ....... 27
Figure 12.-Early Pleistocene shore lines in the Southeastern States. Muich
generalized and in part coniectural --..------- ....................... .............. 35
Figure 13.-Wicomico and pre-Wicomico shore lines in the Southeastern
S states ........... ... .. .................. ...... ...................... .............. .......... 36
Figure 14.-Penholoway shore line in the Southeastern States ........................ 37
Figure 15.-Talbot and post-Talbot shore lines in the Southeastern States 38
Figure 16.-Pamlico and pre-Pamlico shore lines in the Southeastern States 39
Figure 17.-Southwestern part of the Holt sheet, showing an old erosion
surface modified by subterranean solution and trenched by younger
valleys -.-.. ........... ........... ..... ............ ...................... 43
Figure 18.-Part of the Interlachen sheet, showing the Baywood Promontory
flanked by areas of Wicomico terrace and attached to the Lake Region
of Putnam County. The swamp along the eastern margin was a sound
during T albot tim e ................ ........ ....- ............. .... .....................-.......... 45
Figure 19.-View from the cemetery near the airport at Daytona Beach,
showing a dune on the shore of the Pamlico sea ....................................... 53
Figure 20.-A coauina-rock quarry 2.6 miles west of Flagler Beach, Volu-
sia County. The rock is a consolidated beach ridge or bar built by the
waves of the Pamlico sea ..------...--........ .-------.. ............... ........... ...--- 54
Figure 21.-View from the ancient dunes at St. Johns Bluff, Duval County,
across the marshes to St. Tohns River ................................ ........... 55
Figure 22.-A view along the Tamiami Trail in the Everglades. The lumps
of limestone were dredged from the ditch in the foreground ............. 56
Figure 23.-A view in the Rim of the Everelades 23 miles south of Miami.
The jagged surface of the limestone (Miami oolite) was produced by
solution in falling rainwater --....... ......................... ................ 57
Figure 24.-Dunes on Amelia Island near Ft. Clinch .................................. 61
Figure 25.- Dunes on Amelia Island ..... .... ......................................... 62
Figure 26.-Narrow dune ridge south of Jacksonville Beach, Duval County 63
Figure 27.-Daytona Beach. The entire area where the automobiles stand
is covered by water at high tide ....-----.-------..... .. ................-......... .... 64
Figure 28.-Blowing Rocks, 1/ miles north of Jupiter Light. The rock is
hard shell limestone, Anastasia formation, which accumulated as a sub-
merged bar during the Pamlico epoch. It is perforated by tubular solu-
tion cavities, through which water spouts when storm waves strike
the rock. Similar rock is exposed at several places along the beaches






ILLUSTRATIONS- (Continued)
Page
between Cape Canaveral and Palm Beach, but is generally covered by
R recent sand .................---- ..................- -.- -.......... .............. ............. .. .....- -............- ... 65
Figure 29.-A Pamlico bar composed of consolidated Anastasia formation
about 1% miles north of Jupiter Light .........--- ..------- ....-- .......... ..... 66
Figure 30.-Indurated Pamlico bar or beach ridge at Boca Raton Beach 67
Figure 31.-The Marquesas Keys, an American atod. Part of Coast Chart
1252. Scale 1/80,000. Soundings in feet .....................................---...... 71
Figure 32.-Shore of St. George Sound 2 miles east of the bridge over Ap-
alachicola Bay. The shore has recently been eroded back, leaving
stumps and tap roots of pine trees standing in salt water ........................ 77
Figure 33.- Panama City Beach ...................- ...................... --- .......--- .. 78
Figure 34.-The dune ridge west of Panama City Beach ................................ 79
Figure 35.-Dunes on Santa Rosa Island. 5 miles east of Camp Walton .... 79
Figure 36.-Tomoka Creek, a tidal river 4 miles north of Ormond ..--........ 80
Figure 37.-A glimpse of the Halifax River, a lagoon, through palmettos
at O rm ond .........- .............. ........... ...--- -. --- ----........ ....... .. ..............- .... 81
Figure 38.-Santa Rosa Island from the mainland, near Camp Walton, look-
ing across Santa Rosa Sound --............. ...................-- ...-- ..- .....-........-- 82
Figure 39.-Hooked spit at entrance to Choctawhatchee Bay ............................ 84
Figure 40.-View from Valparaiso, Okaloosa County, down Boggy Bayou
to Choctawhatchee Bay ....... ...-.. -... --.. --.-..... -------.--.. -------------- 84
Figure 41.-Subterranean water system of an artesian spring. Water enters
the cavernous limestone through active sinks, flows through caverns,
and emerges through sinks that have been submerged by a rise of the
water table. The vertical scale is much exaggerated .............................. 89
Figure 42.-Salt Spring, Marion County. An artesian spring whose water
is contaminated by passing through caverns in rock saturated with salt
w after .....................-..-....... -....... -................... -....... .. ........ ..- ..... ............. 90
Figure 43.-Bird's-eye view of Silver Springs. Photograph by courtesy of
the management .-..............- ..........-- .......-- --...- --. --.. .... ...... 91
Figure 44.-Rainbow Spring, an artesian spring forming the head of We-
kiva C reek ............. ...... .-.. ..... .................---- -- .....-... ... ......- ..-......... 92
Figure 45.-View down Wekiva Creek from Rainbow Spring ................... 93
Figure 46.-One of the springs forming the head of Crystal River, Citrus
County. The growth in the foreground consists of blooming water
hyacinths, which float on the water and greatly impede navigation ........ 94
Figure 47.-Juniper Spring in the Ocala National Game Refuge .....-....... 95
Figure 48.-Silver Glen Spring, Marion County ...........................-........- 95
Figure 49.-Itchatucknee Spring, Suwannee County ........................... 96
Figure 50.-Waku'la Spring, said to be 185 feet deep ................................ 97
Figure 51.-Wakulla River at U. S. 319. Its source is Wakulla Springs 98
Figure 52.-Troy Spring, Lafayette County. Suwannee River in the back-
ground ........ -.. ..-.... ........... ... ...... .... .....- .......- -- ... ..... 99
Figure 53.-Ponce de Leon Spring, Volusia County ................................. 100
Figure 54.-Water lilies on an arm of Tsala Apopka Lake ..................... 103
Figure 55.-Chipola River at Scotts Ferry, Calhoun County .............-....... 104
Figure 56.-Apalachicola River at Blountstown ................................ 105
Figure 57.-Suwannee River at Branford, Suwannee County .......................... 106
Figure 58.-Wekiva River, a tributary of the St. Johns ........................... 109











SCENERY OF FLORIDA
Interpreted by a Geologist


BY C. WYTHE COOKE


DIMENSIONS OF FLORIDA
When the old Spanish province of Florida was acquired by Great
Britain in 1q63, she divided it into two colonies, East Florida and West
Florida, separated by the Apalachicola River. These geographic divi-
sions have now no legal standing, but the name West Florida is still
in common use. Fast Florida, at least the southern part of it, is more
commonly known as the Peninsula.
The present State includes both East and West Florida. It is
bounded by two nearly straight imaginary lines, by three rivers, and
by a long shore line. The northeastern boundary is formed by St.
Marys River from its mouth to Ellicotts Mound near the head of the
North Prong. From Ellicotts Mound the line runs N. 87" 17' 22" W.
(average direction) to the junction of the Flint and Chattahoochee
Rivers at the head of Apalachicola River, whence it continues up the
Chattahoochee to the thirty-first parallel of north latitude. These
boundaries separate Florida from Georgia. The thirty-first parallel
and Perdido River separate it from Alabama. The Gulf of Mexico,
the Straits of Florida, and the Atlantic Ocean complete tie circuit.
These boundaries enclose an area of 54,861 square miles of land and
3,805 square miles of water-a total area of 58,666 square miles.1
The northern part of Florida is only about 384 miles wide, but the
extreme distance from east to west is about 467 miles. The eastern
part of the State is about 392 miles long from the Georgia boundary
to the tip of the peninsula, but the extreme length from the thirty-first
parallel to the southernmost keys is about 444 miles. The length and
width of Florida are comparable to the distances from Buffalo to
Norfolk and from New York City to Columbus, Ohio. The State
has 1221 miles of tidal shore line, of which 714 miles outline the
mainland and 507 miles surround islands.

'Douglas, E. M., Boundaries, areas, geographic centers, and altitudes of the
United States and the several States: U. S. Geol. Survey Bull. 817, p. 248,
1930.










12 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN


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Floridian Plateau.


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SCENERY OF FLORIDA


FLORIDIAN PLATEAU

The State of Florida occupies only part of a much larger geo-
graphic unit, the Floridian Plateau. The deep water of the Gulf of
Mexico is separated from the deep water of the Atlantic Oc'ean by a
partly submerged platform nearly 500 miles long and about 250 to -41"
miles wide (fig. 1). This platform, the Floridian Plateau, is attached
to the continent of North America and forms part of it. It consists
of a core of metamorphic rocks, presumably the continuation of the
rocks of the Piedmont region of Georgia, buried under more than 4,000
feet of sedimentary rocks, chiefly limestone, which represent the sea-
ward extension of the rocks making up the Coastal Plain of Georgia
and Alabama.
The Floridian Plateau has been in existence for many millions of
years, during which it has been alternately dry land or covered by
shallow seas. During most of this long time the plateau appears to
*have been a very stable region, not subject to violent crustal move-
ments, and therefore free from earthquakes of local origin. The
principal deformation that it has undergone is a very gentle doing
that has made the rocks in the north-central part a little higher than
the corresponding beds in other parts of the plateau. Dislocations of
the rocks (faults), along which takes place the slipping that causes
earthquakes, are completely unknown. The Floridian Plateau is one
of the most stable parts of the earth's crust.
The plateau is broad and nearly level. The highest part projects a
little more than 325 feet above sea level and forms the State of
Florida. An equally great or greater area is submerged beneath the
Gulf of Mexico, and a smaller area beneath the Atlantic Ocean north
of Palm Beach. Both of these submerged parts (the Continental
Shelf) slope gently away from the land at a rate generally less than
3 feet to the mile. The slope, at most places near shore is steeper in
the Atlantic than in the Gulf. Beyond a depth approximating 300
feet, the slope of the sea bottom steepens rapidly. A profile across
the Floridian Plateau is shown in figure 2.







Figure 2.-Profile across the Floridian Plateau along latitude 280N. Vertical
exaggeration about 139 times.






FLORIDA GEOLOGICAL SURVEY--BULLETIN SEVENTEEN


The part of the Floridian Plateau that lies above sea level-the
State of Florida-is divisible into five natural topographic regions:
the Coastal Lowlands, or most recently emerged region, which almost
everywhere lies less than 100 feet above sea level; and the interior,
generally higher, hilly regions, consisting of the Western Highlands,
the Marianna Lowlands, the Tallahassee Hills, and the Central High-
lands. The generalized outlines of these regions are shown in figure 3.


Figure 3.-Topographic divisions of Florida. Maps of the areas enclosed by
dotted lines have been published by the U. S. Geological Survey.


14






SCENERY OF FLORIDA 15

COASTAL LOWLANDS

The Coastal Lowlands border the coast from the Georgia line at
St. Marys River to the Alabama line at Perdido Jiver. They extend
inland a variable distance-abotit 30 miles at Jacksonville, about 60
miles at Kissimmee, about 125 miles at the tip of the Peninsula, about,
40 miles at Tampa, about 10 miles at the mouth of the Withlacoochee,
about 25 miles at Panama City, and 10 or 12 miles at Pensacola.
Their inner edge generally lies at the 100-foot contour line, but where
the adjoining regions are much dissected the boundary is more indef-
inite and may be considerably lower.
The Coastal Lowlands consisted originally of plains representing
four marine terraces (Wicomico terrace, Penholoway terrace, Talbot
terrace, and Pamlico terrace), which were the bottoms of the sea
during four previous high-water levels. These plains remain in nearly
their original, unbroken condition over large areas (see fig. 4), but



















Figure 4.-An emerged sea bottom near White City, Gulf County. Part of the
Pamlico terrace.

elsewhere they have been much modified by underground solution and
surface erosion. As only a comparatively small part of the Coastal
Lowlands is covered by topographic maps, it is not yet possible to
trace these terraces in detail nor to draw with precision the boundaries
between them and the adjoining regions.
A large part of the Coastal Lowlands is covered by pine forests
with an undergrowth of saw palmetto, interspersed with cypress
swamps in the lower, poorly drained areas. Thick clusters of tall






16 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

cabbage palmettos are locally common, particularly along the East
Coast. South of Lake Okeechobee the pine forest gives way to the
saw-grass savannas of the Everglades and the orchid-studded, moss-
hung trees of the Big Cypress Swamp. South of latitude 29 the salt
and brackish shallow coastal waters are overgrown by the interlocking
roots of the mangrove, which grows large in the semitropical climate
of southern Florida.
Except along the coast, where stand the largest commercial and
resort cities and innumerable smaller towns, the Coastal Lowlands are
very thinly populated. Most of the inland towns are mainly agri-
cultural communities, some of which, however, attract tourists.
Truck farming is an important industry, and many tropical fruits are
cultivated. The oranges of the Indian River region, particularly
Merritt Island, are famous for their sweetness.



















Figure 5.-A scene in the Western Highlands. Compass Lake, Jackson County.

WESTERN HIGHLANDS
The Western Highlands, which lie between the Perdido and Apa-
lachicola Rivers, extend inland from the Coastal Lowlands to the Ala-
bama line except where they partly enclose the Marianna Lowlands.
This region includes the valleys of the Escambia, the Blackwater, the
Yellow, the Shoal, and several smaller rivers. The Choctawhatchee
likewise crosses it, entering from the Marianna Lowlands. The
northern part is hilly, but probably not much higher than 300 feet
above sea level, which is the altitude of the crest of the ridge followed






SCENERY OF FLORIDA


by the Old Spanish Trail (U. S. 90) 8 miles west of De Funiak
Springs. The southern part is a broad, gently rolling upland ranging
in altitude from approximately 220 feet to 100 feet above sea level.
It is deeply trenched by narrow, steep-walled valleys, which cut down
nearly to sea level. The areas below 270 feet include remnants of
three marine terraces (Brandywine terrace, Coharie terrace, and
Sunderland terrace), which emerged successively from beneath the
sea during the early part of the Ice Age.
The heads of several streams in the northern part of the De Funiak
Springs quadrangle are circular depressions that seem to have been
originally formed as sinks or lakes, but which have since been captured
by the headward growth 'of surface streams. A good illustration of
this is shown by Lake Sylvia, four miles west of De Funiak Springs.
Lake Sylvia, which lies 60 feet below the upland in a funnel-shaped
sink, appears to be on the verge of being captured by Fish Pond
Branch, which has already drained an adjoining depression. Many
of these sinks were probably formed at a time when the top of the
zone of saturation by undergroundwater stood lower than the present
water table, and the percolation of rainwater seeping downward from
the surface of the earth was correspondingly more active. Rise of the
zone of saturation t9 its present level would have flooded the deeper
sinks and converted them into ponds or lakes. The more sluggish
circulation of underground water would have permitted sand and silt
to close the openings at the bottom of the sinks, in which sediments
would then have begun to accumulate. At the present time surface
streams are cutting well below the zone of saturation beneath the
upland and are therefore able to capture drainage that once flowed
under ground.
An unusual feature of the Western Uplands is the steepness of the
heads of many streams-a feature that has given rise to such geo-
graphic names as Mossy Head, Bear Head, Deer Head, White Head,
and Deep Head. That these streams owe the steepness of their heads
and the narrowness of their valleys to their extreme youth-most of
them appear to have come into existence since the end of the Ice Age
-becomes evident when one compares them with the heads of such
older streams as Titi Creek, which dates from the middle part of the
Pleistocene epoch. The heads remain steep longer than they would
otherwise because the porous sand with which the region is underlain
absorbs most of the rainfall, which therefore causes little surface
erosion. Headward growth of the streams seems to be caused prima-





18 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

rily by perennial springs, which gradually eat back into the upland,
never rising above the level of the zone of permanent saturation.' "
A large part of the Western Highlands consists of pine woods,
much of which is included in the Choctawhatchee National Forest.
Lumber and naval stores are consequently the principal natural prod-
ucts. There are no large towns within the region. De Funiak
Springs, Crestview, and Milton are the county seats of Walton, Oka-
loosa, and Santa Rosa Counties, respectively. The main traffic
arteries are the Old Spanish Trail (U. S. 90) and the Louisville and
Nashville Railroad, which run side by side for many miles, and there
are several less important paved cross roads.

MARIANNA LOWLANDS
The Marianna Lowlands occupy a roughly quadrilateral area in
Jackson, Holmes, and Washington Counties. The region adjoins
Alabama along its straight northern boundary, and it adjoins Georgia
along the Chattahoochee River. The Apalachicola River marks the
remainder of its eastern boundary. Its southern and western limits
are marked by the rise to the Western Highlands, which is caused by
the increasing thickness of the sand (Citronelle formation) that covers
the soluble limestones that lie near the surface in the Marianna Low-
lands.
The Marianna Lowlands is a region of low rolling hills and hol-
lows. (See figs. 6 and 7). It is dotted with sinks, which range from
steep-walled holes like Falling Water, four miles south of Chipley, to
broad, shallow depressions. Many of the sinks contain ponds or
small lakes thickly ringed with cypress trees and other water-loving
vegetation. Others differ in appearance from the surrounding higher
land only by their darker, moister soils.
The Marianna Lowlands are much more thickly populated than
the Western Highlands. Marianna, the largest town, is the county
seat of Jackson County. Bonifay is the seat of Holmes County, and
Chipley of Washington County. Chipley and Cottondale, both rail-
road junctions, are important towns.
The region is traversed from east to west by the Louisville and
Nashville Railroad, which is crossed by the Atlanta and St. Andrews
Bay at Cottondale and connects with the Alabama and Western Flor-

Sharp, Henry S., "Steepheads" and spring sapping in Florida-Holt and
Niceville quadrangles, Florida: Journ. of Geomorphology, vol. 1, no. 3, p. 247,
October, 1938.
SSellards, E. H., Geology between the Apalachicola and Ocklocknee Rivers,
Florida: Florida Geol. Survey, 10th Ann. Rept., p. 27, 1918.






SCENERY OF FLORIDA


ida at Chipley. A branch of the Louisville and Nashville (to Mont-
gomery, Alabama) terminates at Graceville.
The Old Spanish Trail (U. S. 90), the principal highway through
the region, is crossed at Cottondale by the road from Dothan, Alabama,


Figure 6.-A scene in the Marianna Lowlands south of Greenwood, Jackson
County. The clumps of trees grow in sinks formed by the solution of lime-
stone under ground.


Figure 7.-A scene


in the Marianna Lowlands between Greenwood and Bascom,
Jackson County.


to Panama City (U. S. 231) and connects with several other paved
roads. Most of the less important roads are still unpaved.
The Marianna Lowlands is a prosperous farming region. Cotton
is the staple crop.


19






20 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

TALLAHASSEE HILLS
The Tallahassee Hills lie between the Georgia state line on the
north and the Coastal Terraces on the south-a width of nearly 25
miles-and between Withlacoochee River on the east and Apalachicola
River on the west-a length of 100 miles.
Long gentle slopes with rounded summits (see figures 8 and 9)
are characteristics of the Tallahassee Hills except in the western part


















Figure 8.-A scene in the Tallahassee Hills on US 90, four miles east of the
Ochlockonee River.
of Gadsden County, where the upland surface consists of a nearly
level plain, typically developed around Mt. Pleasant. This plain,
which stands 300 feet or more above sea level, appears to be the
highest part of the region. It probably once extended farther east-
ward and formed the original surface of the landmass from which the
Tallahassee Hills have been carved. Its edges are low being cut into
valleys and ridges, particularly along the Apalachicola (altitude at
Chattachoochee about 56 feet), where the relief is greatest.
Tallahassee, the capital of Florida and the county seat of Leon
County, is the largest city of the region. Other important towns are
Quincy, Monticello, and Madison, the county seats of Gadsden, Jeffer-
son, and Madison Counties, respectively. All these places lie on the
Old Spanish Trail (U. S. 90). Several other paved highways radiate
from Tallahassee, and there are many other roads in the region.
Giant live oaks festooned with Spanish moss border most of the un-
improved roads, and many similar trees were destroyed in widening






SCENERY OF FLORIDA.


and straightening the highways. The principal railway serving the
legion is the Seaboard Air Line from Jacksonville to River Junction,
where it connects with the Louisville and Nashville to Pensacola.
Farming is the principal occupation of the inhabitants of the Tal-
lahassee Hills. Cotton is one of the main staples, but much tobacco
is raised in Gadsden County. The valuable fuller's earth .deposits
near Quincy are being actively mined.



















Figure 9.-Live oaks in the Tallahassee Hills four miles east of the
Ochlockonee River.


CENTRAL HIGHLANDS

The northern boundary of the Central Highlands of Florida lies
along the Georgia state line between the Withlacoochee and St. Marys
Rivers, a distance of more than 60 miles. From this boundary the
Highlands extend south-southeastward, following the general trend
of the peninsula, to the vicinity of Glades, Cotinty, a distance Of ap-
proximately 250 miles. The width at the northern boundary is main-
tained for about two-thirds of this distance, beyond which point the
Highlands taper gradually to a blunt southern ending. Along the
northern part of the western boundary (the Withlacoochee River)
,the Central Highlands adjoin the Tallahassee Hills, but elsewhere they
are surrounded by the Coastal Lowlands.
Although the Central Highlands follow the crest of the Floridian
Plateau, they are not symmetrically placed with respect to the shores
of the Atlantic and Gulf but lie somewhat closer to the West Coast


.21






22 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

than to the East Coast. The embayment of the Gulf between Cedar
Keys and Anclote Keys approaches within a few miles of the Central
Highlands in the vicinity of Brooksville and Dunnellon.
The Central Highlands include a considerable diversity of scenery.
Much of the northern part is a nearly level plain (Sunderland terrace)
ranging around 150 feet above sea level. The lower part of this
plain, about 120 feet above sea level, includes the southern edge of the
great Okefenokee Swamp, the greater part of which lies north of the
state line, in Georgia. Somewhat lower, hilly areas around Live Oak
(altitude 108) may have been carved out of this plain, but higher
areas between Houston (altitude 173 and Wellborn (altitude 196), in
Suwannee County, and in Columbia County from Lake City (altitude
200 feet) to the Baker County line stand above it. Little detailed
topographic information about this northern part of the Central High-
lands is available.






t ",. 6t..: 4. ,



. .....








Figure 10.-A lake in the Central Highlands 5 miles west of Interlachen.

Between Gainesville and Pasco County the western part of the
Central Highlands is a succession of hills and hollows interspersed
with broad, low plains (parts of the \Wicomico, Penholoway, and
Talbot terraces), in which are the large shallow Lakes Panasoffkee
and Tsala Apopka and a number of smaller lakes. This region is
devoid of surface streams except Withlacoochee River and a few short
tributaries. The higher parts, where the depth to ground water is
great, are pitted with innumerable quarries from which the Ocala






SCENERY OF FLORIDA


limestone and Suwannee limestone have been excavated. This region
ranges in altitude from 200 feet to less than 40 feet above sea level.
Adjoining this region on the east and extending southward beyond
it to the end of the Central Highlands is what is commonly known as
the Lake Region. (Figure 10). Here the limestone lies farther
below the surface, below the zone of permanent saturation. Its pres-
ence, however, is indicated by hollows in the overlying sand, many of
which extend below the water level and form lakes, of which there
are thousands^of various shapes and sizes. The hills in the Lake
Region rise higher than elsewhere in Florida. The highest point is
said to be Iron Mountain (325 feet abyve sea level), near Lake Wales,
Polk County, on whose summit stanadste beautiful carrillon called
the "Singing Tower."
The Lake Region is the center of the citrus-growing industry. The
hillsides above its lakes are checkerboarded with evenly spaced rows
of orange and grapefruit trees, whose glossy green leaves and golden
fruit are reflected in the quiet waters. Its soil responds readily to
landscape gardening, as is shown by many beauty spots within it. It
is the resort of thousands of winter visitors; in fact, the tourist trade
is one of the most important industries.
The Lake Region is criss-crossed by excellent paved roads, three
\bf which intersect at Lakeland, the largest city of the region. There
are many other prosperous towns too numerous to mention.

GEOLOGIC COMPOSITION

It seems desirable to interpolate at this point a brief description of
the rocks of which the Floridian Plateau is built up because an under-
standing of its geologic composition is necessary to a full interpreta-
Stion of its form. The topography of any region depends in large
measure on the hardness, the p6rosity, and the solubility of the rocks
that underlie it. This fact is particularly evident in Florida, where
there is an intimate relation between the areal distribution of its sev-
eral geologic formations and the features of its landscape.
Limestone, particularly pure limestone such as makes up a large
part of the Floridian Plateau, is soluble in rainwater, and where such
rock lies close enough to the surface to be reached by fresh rainwater,
one finds sinks and caves or lakes, and much of the drainage flows
underground. Where the limestone lies deeper and the overlying
beds are impervious, the surplus rainwater runs over the surface and
carves valleys leading down to the sea. These two strikingly different
kinds of topography characterize different parts of Florida. From






24 FLORIDA GEOLOGICAL: SURVEY--BULLETIN SEVENTEEN

-topography alone one can often infer what kinds of rock underlie a
region.
The geologic formations by which Florida is underlain are named
in the following list in the order of their age, beginning with the
youngest. All crop out at the surface somewhere within the State
except those marked as deeply buried.

GEOLOGIC FORMATIONS IN FLORIDA
QUATERNARY SYSTEM
Pleistocene series:
Melbourne bone bed.
Anastasia formation, Miami oolite, Key Largo limestone, Fort Thompson
formation.
Older terrace deposits.

TERTIARY SYSTEM
Pliocene series:
Caloosahatchee marl, Alachua formation,< Bone Valley gravel, Charlton
formation, Citronelle formation.
Miocene series:
Choctawhatchee formation.
Shoal River formation.
Oak Grove sand.
Chipola formation, Hawthorn formation.
Tampa limestone.
Oligocene series:
Suwannee limestone.
Byram limestone.
Marianna limestone.
Eocene series:
Ocala limestone.;
Undifferentiated limestones, deeply buried.

CRETACEOUS SYSTEM.
Upper Cretaceous series:
Undifferentiated sediments, deeply buried.

PALEOZOIC ROCKS OR OLDER
Metamorphic basement rocks, deeply buried.
The core of ancient rocks that form the foundation of the Floridian
Plateau is known only from the records of the few deep wells that
have reached them in the unsuccessful search for petroleum. The
buried limestone in the Peninsula are somewhat better known, for
many water wells penetrate into them for several hundreds of feet:
The geologic formations that lie at the surface are named in the table:






SCENERY OF FLORIDA


The oldest rock that crops out in the State is the Ocala limestone,
of late Eocene age, which lies at or near the surface in the west-
central part of the Peninsula and in the Marianna Lowlands and
adjoining areas in Alabama and Georgia. Elsewhere in Florida the
Ocala limestone is buried under a variable cover of younger deposits.
The Ocala is a very pure, granular, friable white limestone, generally
too soft for use as building stone but excellent for making lime and
cement and much used as a foundation for roads. It crops out in the
Peninsula from Suwannee County to Pasco County, a distance of
nearly 150 miles, and extends inland about 50 miles from the Gulf
Coast.
The areas of outcrop of the Eocene Ocala limestone are partly
encircled by bands of limestone of Oligocene age, including the
Marianna and the Suwannee limestones. The Marianna limestone, a
white homogeneous soft rock locally used as building stone, is known
in Florida only in the Marianna Lowlands. The Suwannee, a yellow-
ish or white limestone of variable hardness, is more extensively distri-
buted over the Marianna Lowlands and occurs at both ends of the
peninsular area of Ocala. The largest quarries are near Brooksville.
The next younger formation is the Tampa limestone, of early Mio-
cene age, which forms the bluff on Apalachicola River at Chatta-
hoochee and occurs less conspicuously near Tampa. It contains
variable amounts of very fine sand. The Hawthorn formation, which
overlies it and is also of Miocene age, is widely distributed over the
Tallahassee Hills and the Central Highlands. It contains large de-
posits of fuller's earth near Quincy, but in the Peninsula the un-
weathered Hawthorn consists chiefly of sandy phosphatic limestone.
The Hawthorn is partly equivalent to the Alum Bluff group of West
Florida, which includes the Chipola formation, the Oak Grove sand,
and the Shoal River formation. These three formations contain beds
of beautifully preserved fossil sea shells. The Choctawhatchee forma-
tion, of late Miocene age, also contains shells. It is exposed only in
valleys west of Ochlockonee River.
Phosphatic matter that was originally disseminated as small grains
in the Hawthorn formation became concentrated during Pliocene time
in sand and clay residual from the Hawthorn, the product being the
Alachua formation. This formation extends from Gilchrist County
to Hernando County. It has yielded many tons of phosphate rock.
The Bone Valley gravel,.. aco lte poranbus delta deposit occupying
a roughly circular. aea'.in.TlillIobrough; Polk,'Hardee, and Manatee
Counties, is th.t.o'udtce of the "land-pebble" phosphate deposits.
"' " .. "" "






26 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

Phosphate mining has been an important industry in Florida since the
early nineties.
Possibly contemporaneous with the terrestrial Alachua formation
and the estuarine or deltaic Bone Valley gravel is the marine Caloosa-
hatchee marl, which consists typically of a bed of well-preserved sea
shells mingled with a little sand, but which appears to merge south-
ward beneath the Everglades into limestone. The Caloosahatchee,
marl underlies an enormous area in the southern part of the Peninsula
and has been recognized along the eastern strip of the Coastal Low-
lands as far north as Volusia County. The Charlton formation, an.
impure, clayey limestone known only in bluffs on St. Marys River
and in neighboring parts of Georgia, may be an estuarine equivalent
of the Caloosahatchee.
Extensive red sand and gravel deposits, the Citronelle formation,
supposed to be of Pliocene age, extend from Alabama into West Flor-
ida. With them is tentatively correlated the red sand that caps the.
higher parts of the Central Highlands. White kaolin is washed from
this sand in Putnam County.
Each of the marine terraces except the Pamlico is veneered with a
sheet of sand or other sediment, which was deposited on it when it
was the sea bottom. The Pamlico, the lowest, is composed in different
areas of contemporaneous deposits of several principal types, which!
have received individual names. A locally hardened bed of fossil sea
shells mixed with variable proportions of quartz sand, which extends
along the East Coast from the Georgia line to Palm Beach County,
and similar deposits on the West Coast are named the Anastasia
formation. This includes the coquina rock, a popular building stone.
In the southern part of Palm Beach County the Anastasia formation
merges into the Miami oolite, a white limestone containing many small
round grains resembling fish roe. This rock extends southward
through the rim of the Everglades. It forms the floor of Florida Bay
and emerges again in the Florida Keys. The eastern chain of keys,
however, represent a different facies, a dead coral-reef rock, called
the Key Largo limestone, which is used as building stone. (See figure
11). The Federal buildings at Miami and Daytona Beach are faced
with Key Largo limestone. The deposits' of Pamlico age on the West
Coast resemble the Anastasia formation of the East Coast in that,
where they do not consist almost entirely of shells, they are mostly
sand. Hard rock, however, .is rot-.s ;co..amon there as on the East
Coast. Part of tbe-.Ev,erglades is underlaih, by;a Astill different facies,
the Fort Thompson ,formation, an accumulatidn,'ijf' sh3,lls of the little


- F
o'.,






SCENERY OF FLORIDA


clamlike bivalve Chione cancellata with alternating layers of distinc-
tively brackish water shells.
At Melbourne, Vero Beach, and Seminole, Pinellas County, and at
several other places, the Anastasia formation is overlain by a firm,
fine sand called the Melbourne bone bed, which contains the remains
of many sorts of land animals. This bed seems to have accumulated
late in Pamlico time, while the sea still remained at its 25-foot stage
(see page 51). The marshy meadows behind the barrier islands
were the feeding grounds of herds of grass-eating animals and of the





















Figure 11.-A quarry in an emerged coral reef (Key Largo limestone) at
Key Largo.

carnivores that came to prey on them. Their bones were buried in
fine sand blown into the marshes and shallow lagoons. The following
description of the fauna of the Melbourne bone bed is quoted from
Simpson's "The Extinct Land Mammals of Florida."
The richness of the animal life of Florida at this time was extraordinary.
It can only be compared with that of the big game region of Africa. Most,
perhaps all, of the Recent mammals or their immediate ancestors' were already
resent, but there was a host of other and stranger animals besides: lions, saber-
ooth tigers, camels, horses, mammoths, mastodons, ground sloths, giant arma-
dillos, tapirs, dire wolves, peccaries.
Even among the less spectacular animals there were many that no longer
nhabit Florida, or that have. en'tirely'.i vanished from the face of the earth.
hus there were at least* t.)'o '.speCies of capybaras, so-called water hogs, rel-

' Simpson, G. G.,FJo'ri'd Geol. Survey, 20th Ann. Rept., pp. 242-246, 1929.
,, .~,, ,. ,
.'. ,:


27







28 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

atively large rodents of a group which now lives only in South America; in
addition to the Recent type of pocket gopher or "salamander" there was another
of a type now found only in the western part of the continent; the mouse
lemmings, which do not now range so far south, then lived here, and so did
the giant beaver, now extinct, beside which the present beaver is a dwarf.
Flesh-eaters were not lacking to prey on this abundant life. In addition
to the black bear, there was a short-faced bear (Arctodus floridanus) allied to
the strange spectacled bear of South America. There was a dire-wolf (Canis
ayersi), larger than the Recent wolf, and a smaller coyotelike dog (Canis zivi-
veronis) which is also extinct. Cougars and still larger lionlike cats (Felis
veronis) were widespread There was also a saber-tooth tiger (Smilodon flori-
danus), with great stabbing canine teeth.
Ground-sloths, bulky but probably inoffensive relatives of the living South
American tree-sloths, were varied, from the gigantic Megatherium to the rel-
Satively small Megalonyx. An armadillo, like that still living in Texas but over
twice as large, was also common (Tatu bellus), as well as a giant armadillo
(Chlamytherium septentrionale) with movable bands of bony armor like the
living form, and glyptodonts (Boreostracon floridanus), which resembled the
armadillos and were related to them but were encased in immovable armor like
the shell of a turtle, from which their head, legs, and tail emerged.
The horses, of which there were three sorts of somewhat different size,
all belonged to the modern one-toed group, Equus. There were also several
types of tapirs, similar to those still living in South America. Deer were abun-
dant, not only the common white-tail but at least two extinct types of which,
unfortunately, little is known. Peccaries, still living in southern North America
and in South America, were numerous and varied-there appear to have been
some five or six distinct species. Bisons of a sort no longer living were common,
and at least two extinct forms of camels added a strange touch to the land-
scape.
Finally, mammoths and mastodons were so abundant that their teeth are
the most commonly found fossil mammalian remains in the state. The mastodon
was the American true mastodon, Mastodon anericanus, more advanced than
the earlier Pliocene mastodons, with tusks in the upper jaw only. The Imperial
Mammoth, Archidiskodon imperator, most common in earlier Pleistocene time,
arrived from Northern India, Southwest Europe, and even South Africa. The
most abundant elephantine species is the Columbian Mammoth (Archidiskodon
columbi) which is also abundant in the South Carolina phosphate beds and on
the plateaus of Mexico. The true wooly mammoth of the north never reached
Florida.
A fact that will already have struck the reader is the resemblance of this
fauna to that of South America. Capybaras, short-faced bears, sloths, ar-
madillos, tapirs, camels (llamas, etc.), and peccaries are all animals which we
associate with the southern continent at present. This resemblance is due
to two causes: some of the animals did come from South America, others orig-
inated in the north but survive only in the south. At about the beginning of
the Pliocene, South America, which for a very long time had been isolated from
all other continents by the oceans, was reunited with North America. Over
this new Central American land-bridge came members of groups which had






SCENERY OF FLORIDA


been evolving in isolation in the southern continent: the capybaras, porcupines,
ground sloths, armadillos, and glyptodonts. The short-faced bears, tapirs,
camels, and peccaries, on the contrary, then entered South America for the first
time (along with deer, wolves, horses, mastodons, and other animals) but sur-
vived longer in their new home than they did in North America.
Even this brief review of the ancient life of Florida would be incomplete
without some mention of the important role of the state in current investigations
regarding the antiquity of man (that is of the Indians or their predecessors)
in North America. Did man enter North America for the first time after the
final retreat of the great continental glaciers or was he here before that time?
Was man here associated with some of the great extinct animals, as he was in
Europe? If so, does this indicate the great antiquity of man in this continent
or the recent extinction of these mammals? These are questions which have
I.long been asked and which cannot be finally answered even now. Constantly
increasing evidence for the eventual solution of these interesting problems is
,being accumulated, and some of the most important items of this evidence
are being found in Florida. At several places, especially Vero and Melbourne,
human bones and the products of human hands have been found in apparent
!association with the extinct animals described above. If further discoveries con-
firm these and if they can eventually survive the severe scientific examination
and criticism to which they are now properly being subjected, it will appear
that man has been in Florida for some tens of thousands of years and that the
first arrivals in this region disputed the ground with the mammoths, mastodons,
and other great beasts of the glacial epoch.
The final chapter in the history of the animal life of Florida, that of trans-
ition from Pleistocene to Recent times, is a disastrous one, as it has been almost
everywhere. The present fauna of the state is only the poor and colorless
remnant of that which it once supported. Half, or perhaps even two-thirds,
of the Pleistocene mammals are now extinct, and those of their companions
which still survive are not only relatively few in numbers but also generally
the smaller and less striking forms. The rabbits, squirrels, rats, mice, some
of the carnivores, and one of the deer have survived, but the sloths, arma-
dillos, horses, tapirs, camels, mammoths, mastodons, and many others no
longer exist. It is not possible to assign a definite cause to this decimation,
but if present conjectures as to the antiquity of man here prove to be correct
it will seem quite probable that the destruction of animal life by man, still going
on, started with his victory over some of the Pleistocene mammals-a victory
for which one must now feel some regret.

In the Everglades the veneer "of Pleistocene deposits is so thin
that even shallow drainage canals cut through it into Pliocene sand
and limestone, the Caloosahatchee marl and equivalent deposits. The
spoil banks of the canals are thickly strewn with fossil shells, many
representing extinct species. The spoil banks at Ortona Lock on the
Caloosahatchee Canal in Glades County consist chiefly of shells, many
of them beautifully preserved. They make a collector's happy hunt-
ing ground.





FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN


The Pleistocene deposits on the West Coast from Clearwater to
Apalachee Bay are generally thin. Exposures of the underlying
Ocala, Suwannee, and Tampa limestones are numerous.

FACTORS SHAPING FLORIDA
The factors that have been effective in determining the relative
amounts of land and sea on the Floridian Plateau and in producing
the present topography of Florida are four: (1) erosion of the sur-
face, which has been accomplished in Florida chiefly by running
water; (2) solution of the rocks, which, though working chiefly under
ground, has created characteristic surface topography and peculiar
drainage; (3) the work of waves, winds, and currents, which, acting
chiefly along the shores, have wrought changes in the coast line and
have modified the contours of lakes; (4) fluctuations of sea level.
which, by shifting the. shore line back and forth across the Floridian
Plateau, have made notable variations in the area of the land, thus
shifting the scene of activity of coastal' erosion, and have repeatedly
raised and lowered the level of underground water, thus altering the
depths at which solution is most effective.

EROSION BY RUNNING WATER
Erosion of the surface, which in most parts of the earth is the
dominant factor in shaping the landscape, is much less active in Flor-
ida than elsewhere for two reasons: First, because the soil nearly
everywhere in the State consists of sand, which, being porous, is less
rapidly eroded than clay; second, because much of the drainage is
underground. Though some surface material is washed into sini
holes and carried away through open subterranean channels, most of
the sediment is filtered out before it reaches the underground streams,
which emerge as crystal-clear springs.
Erosion by surface streams was more effective in past ages, before
so much of the cover was removed from above the limestones. Then
rivers flowed at the surface and carved normal valleys. They could
not sink into the underlying limestone because the cover was too thick,
Moreover, the ground beneath a plain is normally saturated with
water to a higher level than beneath a deeply dissected region. As
soon as the cover was cut through, water began to circulate morc
freely under ground, the water table was lowered, more rain sank into
the porous sand, and less ran off at the surface. As the surface
streams dwindled the subterranean drainage increased in volume,
Many valleys that had carried continuous streams were tapped by the






SCENERY OF FLORIDA 31

underground drainage and converted into one or more lake basins,
which were flooded when the water table stood high and drained
when the water table stood at lower levels.
Erosion by running water in past ages carved valleys, which later,
partly submerged beneath the sea, became the estuaries that indent
the present coast. Most of the natural harbors the world over lie in
such drowned valleys, and those of Florida are no exception. Run-
ning water is now gradually destroying them by bringing down from
the hills gravel, sand, and mud and depositing the sediment in quiet
water, thus building up shoals, tidal flats, and deltas in the deep water
formerly available for shipping.

EFFECTS OF SOLUTION
Solution has played a conspicuous part in molding the landscape
of Florida. Limestone or limy sandstone lies at or near the surface
throughout much of the State, and even where it is more deeply buried
the cover consists of porous sand, which permits rainwater to per-
colate down to it. The rainwater dissolves some of the lime with
which it comes in contact and carries it away. Millions of tons of
lock have thus been removed from beneath the surface. This slow
removal of the substratum results in either the gradual subsidence of
the surface, forming hollows with no surface outlet, or in the growth
of caverns, which may collapse and form sink holes.
A common form assumed by solution cavities is that of vertical
chimneylike tubes, which lead directly down to the zone of saturation,
at which level they spread out and form horizontal caverns. An
excellent illustration of such a chimney is Falling Water, 4 miles
south of Chipley, where a small stream plunges into a cylindrical,
smooth-walled well about 20 feet in diameter dissolved in limestone.
Many similar chimneys in limestone are disclosed when the sandy
cover is removed in phosphate mines and limestone quarries.
A lowering of the level of ground water, which may result from
any of several causes, permits the extension of chimneys below their
former bottom and the growth of new caverns at the lower level.
Water dripping through the higher caverns deposits some of its dis-
solved lime in the form of pendulous stalactites on their roofs or of
solid upright stalagmites on their floors, or it may cover the walls with
a sheet of travertine. Such accretions may fill some cavities, but
always at the expense of soluble rocks at a higher level.
A rise of the level of ground water floods the caverns and the
chimneys and makes them available to serve as channels for carrying






32 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

subterranean water through solid or less pervious rock. Many of the
great springs of Florida rise through chimneys that extend far below
sea level to caverns serving as conduits for underground streams,
which enter them, perhaps many miles away, through other chimneys
leading to the surface.
Solution may also explain why some surface streams in limestone
areas, such as the Suwannee and the Withlacoochee, which flow to the
Gulf across the Ocala limestone, are not deeply embayed like most
other rivers. During a lower stage of sea level, when the estuaries
of other streams were cut, these rivers may have abandoned their sur-
face channels, sunk into the cavernous limestone, and emerged as
springs beyond the present shore. They cut no valleys to be flooded
when the sea rose to its present level.

WORK OF WAVES, WINDS, AND CURRENTS
At all stages of sea level the work of waves, winds, and currents
has been effective in shaping the shoreline of Florida. Some parts oi
the coast have been built up and extended by shifting sand; others
have been washed away and destroyed. These processes of destruc-
tion and construction have to some extent compensated each other,
for some of the sand washed from one place has found a lodging on
the beach at another.
The work accomplished by waves, winds and currents during past
epochs is more conspicuous than that which has been done during the
Recent epoch, which has been of much shorter duration, and many oi
whose structures are still submerged. Many of the plains of Florida
were smoothed by the waves of sea or lake, and some of their humps
and hollows are ancient bars, dunes, barriers, or beaches constructed
by those agencies. Many features of the present coast are inherited
from preceding epochs, for ancient bars, veneered with Recent sand,
shape much of the present coast line, and even the bulge of the Cape
Canaveral region is partly founded on older rock. The harbors that
indent the coast are also inherited, for they were cut during lower
stages of sea level that preceded the present.
Vegetation is an effective agent in furthering the constructional
work of waves, winds, and currents. Along the northern coast marsh
grass and along the southern coast the mangrove aid in the accumu-
lation of detritus and resist the scour of waves and currents. Both
these types of vegetation add bulk to the growing marshes.






SCENERY OF FLORITA.


FLUCTUATIONS' OF: SEA LEVEL
The relative areas of land and water on the Floridian Plateau
have varied notably during its' long geologic history. For countless
years it was completely submerged, but the water on it appears never
to have been very deep. From time to time crustal movements in
distant parts of the earth deepened or expanded the oceans and caused
the water in them to stand at lower levels. During later epochs the
alternate accumulation and melting of vast polar and subpolar ice caps
caused the level of the sea to fluctuate. These changes in sea level
shifted the shore line back and forth across theliFloridian Plateau, a
slight change in level producing a wide shifting because of the gentle
relief of the surface.
The area of Florida, therefore, has not always been the same.
Most of the records of its former expansions are sunk beneath the
sea, but traces of the former presence of the sea upon the land are
still plainly visible. Evidence of lower stands of the sea is the pres-
ence of drowned valleys and stream-cut channels on the sea bottom.
Submarine springs and subterranean passages extending below present
sea level are suggestions of the same thing, though perhaps not rigid
proof that the sea has risen. Evidences of higher stands of the sea
are sand bars, beaches, and sea shells now far inland.

MARINE TERRACES
These changes of sea level left their marks not only on Florida,
but on coastal regions everywhere. From observations in the field
and from study of maps the writer has determined the approximate
altitudes of a series of abandoned shore lines in the Southeastern
States," and Stearns has measured a series on the Hawaiian islands of
Oahu and Maui." These measurements from opposite sides of the
earth agree remarkably well. It is believed that traces of these shore-
lines remain in many parts of the world and that they can be identified
by their respective altitudes wherever the crust of the earth has not
been deformed since the sea retreated from them, provided that due
allowance is made for local differences in former tidal variation. The
table shows the distances of the shorelines above or below the present
sea level and the names that are accepted for the terraces or the epochs
i
Cooke, C., W., Tentative ages of Pleistocene shore lines: Washington Acad.
Sci. Jour., vol. 25, pp. 331-333, 1935; The Pleistocene Horry clay and Pamlico
formation near Myrtle Beach, S. C.: Washington Acad. Sci. Jour., vol. 27,
pp. 1-5, 1937; and earlier papers.
Stearns, H.- T., Pleistocene shore lines on the islands of Oahu and Maui,
Hawaii: Geol. Soc. America Bull., vol. 46, pp. 1927-1956, December, 1935.


2 A -






34 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

corresponding to them. The table does not list all the changes in sea
level but only those that have occurred since the beginning of the
Pleistocene epoch (Ice Age), and it is probably not complete even for
that recent, comparatively short chapter of earth history.

SUCCESSIVE MARINE SHORE LINES AND TERRACES
(Altitudes in feet)
EASTERN U. S. (Cooke) HAWAII (Stearns)
270, Brandywine Not recognized
Not recognized 250 -, Oiomalu
215, Coharie ( Not recognized
170, Sunderland 170, Not named
Not recognized 55, Kuhuku
Glacial stage -230 to -300, Kahipa
100, Wicomico 95, Kaena
70, Penholoway 70, Laie
42, Talbot 40?, Waialae
Glacial stage -60, Waipio
0, (Horry Not recognized
25, Pamlico 25, Waimanalo
Wisconsin glacial stage Not recognized
0,' Present 0. Present

Inspection of the table shows six fluctuations of sea level-an inter-
mittent drop from 270 feet above the present to 230 or 300 feet below;
arise to 100 feet above, and an intermittent fall to 60 below; an inter-
mittent rise to 25 feet above, and a drop to an undetermined low; and,
last, a rise to the present level. Moreover, the drowned valleys
of the Brandywine shore line (see fig. 12) indicate that the Brandy-
wine sea rose from a lower level. If these epochs of low sea level
correspond to maxima of continental glaciation, all four of the glacial
stages recognized by European and by some American geologists
(others claim there are five) are accounted for.
An attempt has been made in figures 12 to 16 to trace these suc-
cessive shore lines across South Carolina, Georgia, and Florida and thus
to show graphically the shape of the land during different stages of
the Pleistocene epoch. The three highest (fig. 12) are necessarily
more generalized than the lower because they are older and more
fragmentary and because the topography of much of the region in-
cluding them is not mapped. The lines indicating the submerged
shores are merely the 10-fathom and 50-fathom curves taken from
coast charts. They show the general shape of the bottom at those'
depths but probably do not coincide with the actual shore lines. The
detailed mapping of the terraces and the reconstruction of their origi-
nal shore lines must await the completion of a topographic map. ,f









SCENERY OF FLORIDA


00c


LI^


0-
0


figure 12.--Early Pleistocene shdre lines in the Southeastein States. Much
generalized and in part conjectural.


r
r
r
r
r
r






36 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN


Figure 13.-Wicomico and pre-Wicomico shore lines in the Southeastern States.







SCENERY OF FLORIDA


D




\ r\--
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1 '1 ,^ :

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. . . ,


337







38 FLORIDA GEOLOGICAL SURVEY BULLETIN SEVENTEEN


Figure 15.-Talbot and post-Talbot shore lines in the Southeastern States.








SCENERY OF FLORIDA 39


- .. .--- -- --


Figure 16.-Pamlico and pre-Pamlico shore lines in the Southeastern States.






40 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

The writer sees no evidence of tilting or warping of these Pleis-
tocene shore lines nor of the terraces corresponding to them in the
Southeastern States. Variations in altitude of any one terrace can
be explained as due to the original slope of the sea bottom or to later
erosion. The original shore lines, so far as they have been traced,
appear to remain approximately horizontal.
Seven terraces are now recognized in Florida, as follows: Brandy-
wine (270-215 feet), Coharie (215-170 feet), Sunderland (170-100
feet), Wicomico (100-70 feet), Penholoway (70-42 feet), Talbot
(42-25 feet), and Pamlico (25-0 feet). These include all those listed
from the eastern United States except the Horry, which, standing at
sea level and buried under the deposits of the immediately succeeding
Pamlico epoch, is not to be looked for at the surface. Deposits of the
Horry epoch may be exposed between high and low tides in banks of
.canals and estuaries in Florida, as they are in the Carolinas.
Three terraces were recognized in Florida as long ago as 1913,
when Matson' described the Newberry terrace (equivalent to the
Wicomico), the Tsala Apopka terrace (equivalent to the Pen-
holoway), and the Pensacola terrace. In the Pensacola he recognized
two levels, which correspond to the Talbot and the Pamlico. A later
unintentional correlation' of the shore line of the upper Pensacola
level (Talbot) on the East Coast with the shore line of the lower
level (Pamlico) in West Florida resulted in the interpretation that
there had been a slight down-warp of the Pensacola towards the west.
The Pensacola terrace is not a unit, for it represents the sea bottom
during two separate stages of advance separated by an interval of
retreat.
BRANDYWINE TERRACE
The Brandywine terrace has been recognized in West Florida in
the De Funiak Springs quadrangle, where remnants of it are crossed
by the Old Spanish Trail near Argyle and De Funiak Springs. A
short segment of the shore line seems to be preserved along the 270-
foot contour line in the northwestern corner of the map. The map
of the adjoining Niceville quadrangle shows areas of Brandywine
terrace between 250 and 270 feet above sea level near Mossy Head
and on the uplands south of Titi Creek. Other areas probably border
the high plain at the west end of the Tallahassee Hills and possibly

Matson, G. C., Geology and ground waters of Florida; northern and central
Florida: U. S. Geol. Survey Water-Supply Paper 319, pp. 31-35, 1913.
'Leverett. Frank, The Pensacola terrace and associated beaches and bars in
Florida: Florida Geol. Survey Bull. 7, 44 pp., 1931.






SCENERY OF FLORIDA


cap some of the hills in that unmapped region. There may also be
remnants of the Brandywine terrace in the hills of Polk County.
The range of altitude to be expected in the terrace is from 270 to 215
feet above sea level.

COHARIE TERRACE
The range of altitude in the Coharie terrace is from 215 feet at
the shore line to 170 feet above sea level at the outer margin. No
high scarps between the adjoining Brandywine and Sunderland ter-
races are to be normally expected if, as is supposed, there was no
retreat of the sea to levels lower than 215 feet immediately before the
Coharie epoch nor below 170 feet immediately after it. Such scarps
as may exist between these terraces presumably are due to the original
gentle slope of the sea bottom accentuated by beach erosion during
Coharie and Sunderland time or by subsequent subaerial erosion.
The parts of the DeFuniak Springs, Niceville, and Holt quad-
rangles over which the Coharie terrace originally extended are now
very deeply eroded, but there still remain between 215 and 170 feet
above sea level many flat hilltops that presumably are only slightly
altered remnants' of the Coharie terrace. Some of the Tallahassee
Hills may be capped by patches of Coharie terrace. The Seaboard
Air Line Railway appears, to cross an area ot Coharie in Suwannee
County between Houston and Wellborn and another, larger area in
Columbia County between a point west of Lake City and the Baker
County line.
Alachua County also contains a large area, shown on the map of
the Arredondo quadrangle north of Gainesville. This area, whose
highest parts reach 200 feet above sea level, is a poorly drained plain
containing many shallow depressions and some deep sinks. The most
notable sink is the Devil's Mill Hopper.
There are probably patches of Coharie terrace in Polk County
between Lakeland, Mulberry and Bartow and in the vicinity of Lake
Wales.

SUNDERLAND TERRACE
The Sunderland terrace, which ranges in altitude from 170 feet at
its original shore line to 100 feet above sea level, crosses the southern
part of the De Funiak Springs, Niceville, and Holt quadrangles in a
band several miles wide. This band shows evidence of two different
cycles of erosion. The first, which has produced a gently rolling sur-
face, apparently has been in operation ever since the terrace emerged






42 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

from beneath the sea and has produced only low local relief. The sec-
ond, much more recent, is cutting through the rolling upland narrow,
steep-walled valleys, which lead down to tidewater, where their lower
courses are drowned. This cycle appears to have begun late in the
Ice Age (Wisconsin glacial epoch) and is still extending its valleys
headward. Besides these two cycles of surface erosion, the presence
of many shallow depressions and sinks shows that the region is also
being attacked by solution of the rock beneath the surface. Perhaps
the topography of the first cycle is due chiefly to solution. (Fig. 17)
The Sunderland terrace is characteristically developed in the
northern end of the Central Highlands. In this region, which includes
the southern borders of Okefenokee Swamp, New River Swamp, and
Turkey Creek Swamp, many of the inequalities of the surface appear
to be original; that is, they existed as hollows or shoals when the
ocean covered the present land. The streams head as runways in
swamps, which, as they emerge into better-drained land, coalesce and
become enclosed in narrow, shallow valleys. The nearly level upland
area shown on the maps of the MacClenny and Lawtey quadrangles
ranges in altitude from 150 to 120 feet above sea level, with former
bars and barrier islands reaching a maximum of 240 feet on Trail
Ridge and with a minimum altitude, of 50 feet where St. Marys River
cuts across the ridge. Most of the region is wooded (pine and
cypress) and very thinly settled.
Trail Ridge.-On the eastern edge of this northern part of the
Sunderland terrace and separating it from the Coastal Lowlands
stands Trail Ridge. The ridge probably begins in Clay County not far
south of latitude 300, from which line it extends in a direction a few
degrees west of north into Georgia. The ridge is about 130 miles
long. Its crest lies nearly a mile east of the Bradford-Clay County
line at latitude 30, crosses the county line at Highland, and passes
about 2 i miles west of the Baker-Duval County line, where the ridge
is cut through by St. Marys' River. The crest of the ridge slopes
gradually from an altitude of 240 feet above sea level at the south
end of the Lawtey quadrangle to 170 feet at a point 22 miles south
of the St. Marys. It is 178 feet above sea level west of St. George,
Ga., but somewhat lower elsewhere in Georgia. The east side of
Trail Ridge rises higher above the bordering plain than the west side,
for on the east it adjoins the Coastal Lowlands, here standing 100
feet above sea level, and on the west it borders the Sunderland ter-
race, there at an altitude of 130 to 150 feet above sea level.













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modified by subterranean solution and trenched by younger valleys.


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44 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

Some persons interpret Trail Ridge as the result of a fold or dis-
location of the earth's crust. The writer sees no evidence in support
of such an origin. The ridge seems to be simply an accumulation of
sand transported by alongshore currents during a higher stage of the
ocean and dropped on the bottom in the form of a spit, bar, or bar-
rier island (see fig. 12) much like the Hatteras "Banks" of North
Carolina. The higher, southern part may have been built up 60 tr 70
feet above the contemporary level of the Sunderland sea by the winds,
just as the dunes at Cape Henry now tower 100 feet above the mouth
of Chespeake Bay. Or, more likely, construction of the ridge may
have begun earlier, during the Coharie or even the Brandywine epoch,
and continued through the Sunderland epoch until the entire ridge was
laid bare by the post-Sunderland emergence. The narrow trench cut
through the ridge by St. Marys River seems to lie within a former
inlet leading to the sound enclosed by Trail Ridge during Sunderland
time. Evidence of this is a long sandbar trailing southwestwardly
from the south side of the inlet.
Trail Ridge now stands as a barrier between the nearly level
Sunderland terrace and the Coastal Lowlands east of it. The ridge
acts as a dam to prevent the escape of water in its most direct course
to the ocean. Some of the water, collected in the three prongs of St.
Marys River and their tributaries, flows through the gap in the ridge,
but most of it accumulates in swamps, from which it finds a tortuous
passage to the Gulf of Mexico through Suwannee River and its tribu-
taries. Trail Ridge, therefore, forms part of the divide between the
Atlantic Ocean and the Gulf of Mexico.
In spite of its importance in diverting the natural course of the
drainage, Trail Ridge is not a conspicuous feature of the landscape,
for its slopes are gentle, and it and the adjoining plains are covered
with pine forests, which obstruct the distant view. Nevertheless, it
shows very plainly on topographic maps.
Baywood Promontory.-Somewhat similar to Trail. Ridge in ap-
pearance and perhaps in origin is the feature that, for want of a better
name, may be called the Baywood Promontory. The Baywood Prom-
ontory begins at a corner of the Lake Region of Putnam County
3 miles northeast of Interlachen and juts north-northeastward into
the Coastal Lowland beyond the north edge of the Interlachen quad-
rangle, a distance of more than seven miles (see fig. 18). The main
part of it is a sand ridge about two miles wide whose highest point in
the mapped area is 220 feet above sea level. One lower prong ex-
tends northwestward to Florahome, where it is 125 feet high and flat-

















































































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-


Figure 18.-Part of the Interlachen sheet, showing the Baywood Promontory
flanked by areas of Wicomico terrace and attached to the Lake Region of
Putnam County. The swamp along the eastern margin was a sound during
Talbot time.


to,,'w
.aw. A






46 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

topped. The ridge curves westward around the head of Etonia Creek
and apparently terminates not far beyond the edge of the quadrangle.
The ridge may have grown as a sand spit attached to an island in
the Sunderland sea or possibly in the Coharie sea, or it may have
formed part of the mainland, from which it has subsequently become
partly detached by the growth of a large lake basin west of it. Bay-
wood itself stands on a spit or bar built into the Sunderland sea.
Other areas of Sunderland terrace.-The lack of topographic maps
of the southern part of the Peninsula makes it impossible to describe
with assurance the extent of the Sunderland terrace in that region.
The wide plains crossed by the headwaters of Withlacoochee River in
southern Lake and northern Polk Counties presumably form part of
it, as likewise does the plain in Manatee and Hardee County crossed
by State Highway 32 beginning at a point eight or ten miles east of
Parrish and extending eastward beyond Ft. Green Springs (altitude
122 feet).

WICOMICO TERRACE
The oldest, highest terrace in the Coastal Lowlands is the Wicomico,
whose shore line (figure 13) now stands 100 feet Above sea level,
and whose lower limit of altitude is 70 feet. The Wicomico abuts
against the Central and Western Highlands and the Tallahassee Hills
and extends up into them along abandoned sounds and estuaries.
The terrace is well shown on a group of topographic maps of the
northeastern part of the State, where its shore line follows the -foot
of Trail Ridge. From an altitude of 100 feet above sea level at the
foot of Trail Ridge, the Wicomico slopes eastward within a mile to
about 85 feet and maintains approximately that height nearly to its
eastern boundary. Along the Seaboard Air Line R.ailway and US 90
west of Jacksonville, the terrace extends from a point about 4'/2
miles east of MacClenny nearly to Marietta, a distance of 1534 miles,
where it adjoins a narrow strip of the next lower, Penholoway ter-
race.
This northeastern part of the Wicomico terrace has been very
little eroded. Much of its surface is a succession of low sandy ridges
separated by shallow swampy swales, which appear to represent origi-
nal hummocks and hollows on the former sea bottom. A low ridge
three to four miles north-northwest of Whitehouse, Duval County,
encircled by the 100-foot contour line on the map of the Cambon
iliuilr.ini., apparently was a low island or shoal in the Wicomico
sea. The outer edge of the Wicomico is indented by short, deep,





SCENERY OF FLORIDA


narrow valleys, some of which are cut below the 20-foot contour line,
which debouch on the-lowest, Pamlico terrace.
The map of the Interlachen quadrangle shows a two- to five-mile-
wide band of Wicomico terrace between low, swampy land (Talbot
terrace) on the east and the high sandy ridge of the Baywood Prom-
ontory on the northwest. High tide in this region seems to have
reached two or three feet above the 100-foot contour line. This
band of Wicomico terrace continues as the former bed of a strait that
separated the tip of the mainland from the group of islands in the
Wicomico sea that now form the highlands of the Peninsula.(See
figure 13.) It apparently connects through an unmapped area north
of Orange Lake with a wide area of Wicomico terrace in the southeast
part of the Arredondo quadrangle, which area probably continues to
the former seashore in Levy or Gilchrist Counties. This passage
through the Central Highlands has been greatly altered by solution
and collapse of the underlying limestone.
The passageways through the Central Highlands, the Tallahassee
Hills, and the Western Highlands that are occupied by extensions of
the Wicomico and lower terraces appear to be valleys formed by
solution and erosion chiefly during the glacial epoch immediately pre-
ceding the Wicomico. As shown by the table on page 34 Stearns
estimates that the sea stood 230 to 300 feet below its present stage
during this epoch, which he names Kahipa. When the sea rose to
the 100-foot level of the Wicomico, it flooded these valleys and con-
verted them into estuaries. The deepest parts remained flooded when
sea level dropped after Wicomico time successively to the 70- and 42-
foot stages of the Penholoway and Talbot epochs.
Another wide band of Wicomico terrace represents a tortuous
passage that bisects the Central Highlands from Orange Lake south-
ward to Hillsborough County. During the Wicomico epoch this pas-
sage was a large bay or sound dotted with islands, on one of which
stands Ocala. One entrance to the sound opened into the Gulf be--
tween Kathleen, Polk County, and Richland, Pasco County, and there
were other outlets at Dunnellon and perhaps in Levy County.
Winter Park, Orlando, and Pinecastle stand on an island in the
Wicomico sea separated from the largest peninsula, which extended
southward beyond Sebring, Highlands County. The Atlantic shore
of this largest island passed about four miles east of Haines City,
Polk County.
In West Florida the W-icomico terrace is narrow, considerably
ti'enched by valleys, and somewhat modified by solution. An area of





48 FLORIDA GEOLOGICAL SURVEY--BULLETIN SEVENTEEN

15 square miles or more of Wicomico terrace occupies the south-
eastern part of the Niceville quadrangle. On the map of the Holley
quadrangle the high-tide mark of the Wicomico sea appears, to stand
a few feet above the 100-foot contour line.

PENHOLOWAY TERRACE
The Wicomico terrace is fringed by a narrow belt of the next
lower, Penholoway terrace, which generally does not exceed two
miles in width in the northeastern part of Florida. The Penholoway,
likewise, is an emerged sea bottom, whose shore line (fig. 14) now
stands approximately 70 feet above sea level, and whose lower limit
of altitude is about 42 feet above sea level. As the rise from the
Penholoway terrace to the Wicomico terrace is generally not more
than 10 feet, the scarp separating the two terraces does not commonly
show on topographic maps. There is an indication of it in sec. 29,
T. 1 S., R. 25 E. (Cambon quadrangle),.where the land rises from
66 to 80 feet above sea level within a quarter of a mile.
In South Carolina there is a great development of sand spits along
the Penholoway shore," but none have been detected on the few topo-
graphic maps of Florida, and many such features are unrecognizable
without maps.
When the sea fell to the Penholoway level, the group of islands
in the Wicomico sea coalesced with the mainland into a long peninsula
indented by much-narrowed channels separated from the higher land
by strips of Wicomico terrace. Level areas at the proper altitude for
the Penholoway terrace partly surround Orange Lake and extend
southward across the eastern part of the Citra quadrangle, and others
border Withlacoochee River in the Dunnellon, Tsala Apopka, and
Panasofkee quadrangles. However, parts of these low areas may
represent land areas above the Penholoway sea that have been de-
graded to their present level since the end of that epoch.
Details of the extent of the Penholoway terrace west of the Cen-
tral Highlands are lacking, but it seems to be wider there, particularly
between High Springs, Alachua County, and Cross City (altitude 53
feet), Dixie County. It appears to occupy much of the Pinellas
Peninsula between Clearwater and Old Tampa Bay, and to extend
from the northeastern part of Tampa at least as far as Harney, Hills-
borough County. It apparently extends from a point three or four
miles south of Tallahassee to or a little beyond the Wakulla County
line.
SCooke, C. W., Geology of the Coastal Plain of South Carolina: U. S. Geol.
Survey Bull. 867, pl. 6, facing, p. 10, 1936.





SCENERY OF FLORIDA


A group of topographic maps in West Florida shows the Pen-
holoway terrace as a much-dissected narrow band fringing the
Wicomico terrace between the 50-foot and the 70-foot contour lines.
Parts of secs. 1, 2, 3, and 11, T. 1 S., R. 20W., near Portland, Walton
County (De Funiak Springs quadrangle) represent the Penholoway
terrace.
The seaward boundary of the Penholoway terrace is generally
more conspicuous in Florida than the landward, for it has been
steepened by erosion, which at some places has destroyed the normally
adjacent Talbot terrace. At some places the Talbot was probably
removed during the low stage of sea level that followed the Talbot
epoch and preceded the Pamlico epoch, whose shore line, about 25
feet above sea level, there adjoins the Penholoway terrace.

TALBOT TERRACE
The shore line of the Talbot terrace (figure 15), determined from
studies in other States to stand about 42 feet above sea level, is rarely
conspicuous, for it does not abut against terraces higher than the
Penholoway, whose outer edge is commonly less than 50 feet above
sea level, except where the Penholoway was cut away by the Talbot sea.
The Wicomico, Penholoway, and Talbot epochs apparently followed
one another without intermission, the division between them being
marked by successive drops of sea level from 100 to 70, to 42 feet
above present sea level without intervening lower stages. The end of
Talbot time, however, was marked by a 100-foot drop in sea level to
a position estimated by Stearns (see table, page 34) as approxi-
mately 60 feet below the present sea level. He names this stage the
Waipio. During this time of low water, which presumably was
contemporaneous with the next-to-the-last great period of continental
glaciation, the rate of erosion was speeded up by the quicker run-off
of surface water, and solution was accelerated by the lower position
of the water table in the porous limestone. As a result, many gullies
cut headward through the narrow bands of Talbot and Penholoway
terraces' into the broader Wicomico, locally destroying the lower ter-
races completely; and existing solution basins were enlarged and
some new ones formed.
In the Hilliard and Cambon quadrangles the Talbot terrace is
wanting or obscure where one would expect to find it along the outer
edge of the Penholoway terrace; but in the Middleburg quadrangle it
appears below the forks of Black Creek east of Middleburg, Clay
County, and continues southeastward across the corner of the Orange





50 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

Park quadrangle nearly to Green Cove Springs. This part of the
Talbot terrace was the floor of a bay or sound generally 10 to 20 feet
deep, which was separated from the open ocean by wide shoals termi-
nating in narrow barrier islands. One such island extended south-
ward 12 miles from the present eastward course of St. Johns River,
passing four miles east of Jacksonville. This island is outlined by
,he 50-foot contour line on the maps of the Jacksonville and Orange
Park quadrangles. Other Talbot shoals and islands are shown on
the map of the Palm Valley quadrangle.
A very low Talbot barrier island crosses the south-central part of
the Bakersville 742' quadrangle, on which it terminates in a south-
southeastwardly curved hook near Ellzey (altitude 46 feet), continues
through the Elkton 7J}' quadrangle past Vermont (altitude 48 feet),
and merges into tidal flats at the southeast corner. An adjacent,
parallel island crosses the southeast corner of the Crescent Beach 7f4'
quadrangle into the unmapped area south of it. These low islands
appear to have been built up above the Talbot sea by waves and winds.
The Talbot terrace in this, the northeastern part of Florida is very
nearly level. It ranges in altitude from about 25 feet at the shore
line of the adjacent, scarcely distinguishable Pamlico terrace to about
50 feet at the crest of the barrier islands. Much of the terrace is
marked by alternating narrow bands of low sandy ridges and shallow
swampy depressions, which generally run parallel to the present c6ast-
line and apparently represent bars and hollows in the Talbot sea bot-
tom.
In the eastern part of the Interlachen quadrangle and in the ad-
joining part of the Palatka quadrangle (Bull. 7, fig. 1) are low areas
occupied by the Talbot and Pamlico terraces, which obviously were
broad waterways surrounding high islands during Talbot time.
These areas may mark an old course of the St. Johns River, but, as
the adjoining highlands are dotted with sinks and lake basins, it seems
probable that underground solution had something to do with their
formation. They may have originated as solution basins formed
during the glacial stage that preceded the Wicomico epoch. They
probably were continuously submerged by the sea during the
Wicomico, Penholoway, and Talbot epochs. The 40-foot contour
line, the nearest to the supposed high-tide level of the Talbot, sur-
rounds the areas of higher land.
A well-marked Pleistocene shore line, presumably the Talbot al-
though its altitude is not known, is crossed by the road to Okeechobee
(Florida 8) 3y2 miles east of the Atlantic Coast Line Railroad near






SCENERY OF FLORIDA


Childs, Highlands County. The shore line is bordered by a ridge of
sand dunes.
From observations made with a barometer it appears that the
Talbot terrace extends 11 miles along US 231 from Panama City to
Bayou George, Bay County, beyond which lies the Penholoway ter-
race.
In West Florida the Talbot terrace shows in the Point Washington
quadrangle as the wedge-shaped head of the peninsula separating
Choctawhatchee Bay and the delta of Choctawhatchee River from the
Gulf of Mexico. North of the river it fringes the Penholoway ter-
race as far west as Lafayette Creek near Freeport, Walton County.
In the adjoining Villa Tasso quadrangle it is very narrow or wanting.
In the Mary Esther quadrangle a triangular wedge of Talbot terrace
in secs. 4 and 5, T. 2 S., R. 23 W., terminates on Choctawhatchee Bay
a quarter of a mile west of Black Point. A larger area at the head
of East Bay Swamp extends westward across the Holley quadrangle
through the central part of the peninsula south of East Bay Swamp
to East Bay. In the vicinity of Pensacola the Talbot terrace seems to
be best developed west of Bayou Chico.

PAMLICO TERRACE
A glacial epoch, with lowered sea level, succeeded the Talbot epoch.
In the Atlantic region it has no name; in the Pacific region it was
called the Waipio epoch (see page 34). Assuming that the changes
in sea level were uniform over the world, at the end of the Waipio
epoch sea level rose from its low of approximately -60 feet, paused
a while (Hcrry epoch 1) near its present location, and then resumed
its rise to a height of 25 feet above present sea level. The valleys
that had been eroded while the sea stood low were flooded by tidal
waters to the height of the Pamlico shore line and began to be filled
with sand and silt. Conditions in the Pamlico sea must have been
favorable for the growth of shellfish, for their accumulated sea shells
underlie the Pamlico terrace in great numbers. Where cemented
together by percolating limewater this shell bed forms the coquina
rock, a popular building stone.
In the northeastern part of Florida the mainland shore of the Pam-
lico sea lay 25 to 30 miles west of the present coast. It was fairly
straight although broken by many small reentrants that extended a

" Cooke, C. W., The Pleistocene Horry clay and Pamlico formation near Myrtle
Beach, S. C.: Washington Acad. Sci. Jour., vol. 27, pp. 1-5, 1937.






52 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

few miles into the adjoining higher terraces and by a broader bay now
followed by Black Creek. Ten to fifteen miles off shore several large
islands of Talbot terrace rose as much as 35 feet above water and
partly enclosed a large bay, which narrowed near Green Cove Springs
to a lagoon only'5 miles wide, now partly occupied by St. Johns River.
The lagoon widened to an island-studded bay neat Palatka and ap-
proached within a few miles of the coast near Bunnell. There may
have been inlets giving passage to the open ocean near Ormond,
Volusia County, but the lack of topographic maps makes verification
difficult. South of Sanford, Seminole County, the lagoon lay farther
east and was separated from the ocean by narrow barrier islands.
The nearly straight shore of the mainland lay west of the headwaters
of St. Johns River. It is crossed by US 192 near the Brevard-
Osceola County line about 16 miles west of Melbourne.
The Pamlico seashore continued south-southeastward parallel to
the present coastline and about 25 miles west of it to the vicinity of
Indiantown, Martin County, where it turned northwestward to
Okeechobee. Thence it circled ten miles inland from Lake Okeecho--
bee nearly to Caloosahatchee River, which it paralleled to an un-
determined point near Gilchrist, Charlotte County. A strait ranging
in width from 5 to 15 miles, through which Caloosahatchee River now
runs, separated the mainland from a large island, whose seashore
passed south of Immokalee, Collier County.
The Gulf shore of the Pamlico sea was crooked, generally narrow,
and indented by many estuaries. There was an island along the
Western side of the Pinellas Peninsula from a point near Seminole to
the vicinity of Tarpon Springs. In Pasco and Hernando Counties
the shore lay two to six miles inland from the present coastline. At
the mouth of the Withlacoochee it lay eight miles inland, and farther
north in Levy County it passed about midway between Bronson and
Cedar Keys. It lay somewhere west of a line connecting Cross City
(altitude 53), Dixie County, and Perry (altitude 54), Taylor County.
It is crossed by the railway from Tallahassee to St. Marks about 2
miles south of Woodville.
The road from Port St. Joe to Wewahitchka, Gulf County, crosses
the Pamlico shoreline some nine miles south of Wewahitchka. West
of Panama City, Bay County, the present shoreline follows the Pam-
lico westward half-way across Walton County, where a pointed pen-
insula shut off an expanded Choctawhatchee Bay during Pamlico time.
The peninsula that now separates East Bay from Escambia Bay was






SCENERY OF FLORIDA


under water then; and an expanded Pensacola Bay extended farther
up the Yellow, Blackwater, and Escaimbia Rivers. The Pamlico
shoreline crosses the city of Pensacola, from which it extends north-
westward to Perdido River.
North of the Everglades the Pamlico terrace narrows considerably
on both sides of the Peninsula. The broad meadows traversed by the
headwaters of St. Johns River represent this terrace, and the river is
bordered by the terrace to its mouth. At Daytona Beach the Pamlico
terrace, overgrown by cabbage palmettos, lies mostly about 15 feet
above sea level. Pits at the rifle range show that it is underlain by
unconsolidated shells and sand. The shore line is crossed by US 92
at the cemetery 1.8 miles west of the Halifax River at Daytona Beach,
where the adjoining Talbot terrace, standing about 40 feet above sea
level, is capped by a row of dunes composed of fine yellow sand
leaching white, which reach 60 feet or more above sea level. (See
fig. 19.)





















Figure 19.-View from the cemetery near the airport at Daytona Beach, showing
a dune on the shore of the Pamlico sea.

A beach ridge or bar of the Pamlico sea is crossed by the old brick
road six miles east of Bunnell and 2.6 miles west of Flagler Beach,
Volusia County. It is composed of coarse fragments of sea shells too
large to have been carried inland by the winds. The layers slope
seaward. The ridge rises 10 feet above the plain east of it and about


53





FLORIDA GEOLOGICAL. SURVEY-BULLETIN SEVENTEEN


5 feet above the plain west of it. Quarries on each side of the road
yield coquina, some of which is consolidated. (See fig. 20.)
The crescent-shaped hills between Trout Creek and Cedar Creek
a mile northeast of the Jacksonville city prison farm are ancient dunes.
They are composed of fine gray sand, which is now effectually
anchored by a pine forest. The highest dunes rise 100 feet above
sea level. They seem to have been cast up on the shore of an inlet
leading to a broad Pamlico lagoon.
St. Johns Bluff, on the south side of St. Johns River about 6 miles
from the ocean, is also a group of dunes,.now tightly anchored by a
jungle of liveoaks, bushes, and dwarf palmettos. It rises steeply




















Figure 20.-A coquina-rock quarry 2.6 miles west of Flagler Beach, Volusia
County. The rock is a consolidated beach ridge or bar built by the waves
of the Pamlico sea.

from tidewater to a height of 80 to 90 feet. (See fig. 21.) The side
next to the river seems to have been steepened by undercutting, for
it is steeper than the windward side of a normal dune. These dunes
probably are of Pamlico age, but they may have been formed early
in the Recent epoch while the space now occupied by broad salt
marshes was still open water.
The Pamlico terrace, which is encircled by the shoreline just de-
scribed, is most extensively developed in the southern part of .the
Peninsula, where it occupies all the region south of Lake Okeechobee
except the island of Talbot terrace south of Caloosahatchee River be-


54





SCENERY OF FLORIDA


tween La Belle and Immokalee. This region includes the Big Cypress
Swamp, the Everglades, a higher strip along the Atlantic coast called
the rim of the Everglades, and the Florida Keys.
Big Cypress Swamp.-The Big Cypress Swamp occupies' a large
area in northern Collier County. Its soil probably contains much sand,
in which respect it differs from the Everglades, whose surface is lime-
stone or peat underlain by limestone. This difference in soil may
account for the greater abundance of trees in the Big Cypress Swamp,
although cypress trees rooted in limestone grow along the western
part of the Tamiami Trail. Sand extends along the Trail for 25 or 30
miles southwest of Naples.




















Figure 21.-View from the ancient dunes at St. Johns Bluff, Duval County,
across the marshes to St. Johns River.

The Everglades.-The Everglades occupy a nearly level plain,
which slopes from 15 feet above sea level at the south shore of Lake
Okeechobee to sea level at the tip of the Peninsula, a distance of more
than 100 miles. On the west the Everglades merge into the Big
Cypress Swamp, which presumably is a few feet higher. On the
south and southwest the Everglades are bounded by mangrove
swamps, which separate them from the open waters of Florida Bay
and the Gulf of Mexico.
When Florida was first settled, the waters from Lake Okeechobee
overflowed the indefinite south shore of the lake and passed south--
ward without well marked channels across the Everglades to the Gulf.


55






56 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

In wet seasons much of the Everglades was then submerged and was
covered by a thick growth of tall sawgrass. A dike now follows the
south shore of the lake and cuts off drainage in that direction except
through artificial canals, by means of which the level of the lake is
maintained about 16 feet above sea level. These canals have also
drained large areas of the Everglades and converted it into farm land,
which, however, is still subject to occasional overflow.
The Everglades, as the name implies, are open grassy meadows.
(See fig. 22.) Here and there clumps of trees lend variety to the









. -- m .



~ .






Figure 22.-A view along the Tamiami Trail in the Everglades. The lumps
of limestone were dredged from the ditch in the foreground.

landscape. During the breeding season flocks of snowy egrets fill
the air while solitary herons crane their long necks through the tall
grasses.
The Everglades differ from most swamps and boggy places in the
scarcity of trees and in their lack of ordinary mud and clay. The
entire Everglades are underlain by hard limestone, which is cushioned
in the lower, generally flooded parts by deposits of peat. Fires are
frequent in the drained peat bogs, which, once destroyed, can never
be replaced. Where peat is absent, bare limestone shows at the sur-
face.
Rim of the Everglades.-The Everglades are bordered on the east
by a rim of slightly higher land a few miles wide on which stand West
Palm Beach, Fort Lauderdale, Miami, and many other prosperous






SCENERY OF FLORIDA


resort towns. The rim of the Everglades is built of white cross-
bedded limestone (Miami oolite) whose bare surface is rendered
jagged by small solution pits (see fig. 23.) Its diagonal bedding
planes, crossed by horizontal beds, show that the limestone accumu-
lated in shallow water probably as a slightly submerged bar, which
shut off a wide shoal only 10 to 25 feet deep, now the Everglades,
from the deeper water of the Atlantic. Lake Okeechobee, a great
body of fresh water 25 to 30 miles across, marks a slightly deeper
part of this epicontinental sea, its bottom in the deepest part being



4 -
'P -" '^ / l am ,
















Figure 23.-A view in the Rim of the Everglades 23 miles south of Miami.
The jagged surface of the limestone (Miami oolite) was produced by solu-
tion in falling rainwater.

near present sea level, fifteen feet lower than the neighboring Ever-
glades.
A canal at Moore Haven crosses the low divide (18 feet above sea
level) between the ocean and the Gulf and connects Lake Okeechobee
with Lake Hicpochee, now drained, the original source of Caloosa-
hatchee River. The Intracoastal Waterway enters Lake Okeechobee
through the St. Lucie Canal from Stuart, passes through this canal
and down the Caloosahatchee Canal to Fort Myers.
Florida Keys.-The limestone floor of the Everglades continues
southward beneath the shallow waters of Florida Bay and emerges
again in the Florida Keys. These islands are of two types. The


3-


57'





58 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

eastern keys, which terminate at Loggerhead Key, are long narrow
islands composed of limestone (Key Largo limestone) containing
large heads of corals in place, just as they grew. They evidently were
formed as coral reefs that grew at the edge of deep water in the
Pamlico sea, to whose surface they did not quite reach. The western
keys, which lie behind the eastern keys and extend beyond them to
Key West, were merely a shoal in the Pamlico sea. They are similar
in origin to the rim of the Everglades and are composed of the same
kind of oolitic limestone. This shoal extended, with a few breaks,
westward to the Dry Tortugas. Its continuation beyond Key West
is marked by the Marquesas Keys and a few smaller islands.
In 1851 the eminent naturalist Louis Agassiz reported" that flor-
'ida had been extended southward from a point at least as far north
as latitude 280 by the growth of a succession of coral reefs across a
bottom not deeper than 12 to 20 fathoms and by the burial of the
reefs beneath an accumulation of detritus cast up by the sea to
heights a few feet above sea level, the growth of the reefs and the
accumulation of the detritus having been completed without change in
the relative level of the sea and the platform. He further supposed
that Florida could not grow beyond the present living reef, for the
water there is too deep for corals to take hold and grow. This theory
was' elaborated by Joseph Le Conte in 1857, incorporated in his Ele-
ments of Geology in 1878, and was generally accepted for many years.
Little was known about the interior of Florida when this theory was
formulated, and facts since discovered have shown it to be false, it
does not apply even to the Everglades, where marine Pliocene rocks
containing few corals and no known reefs now stand above sea level
Other areas of Pamlico terrace.-Both shores of Hillsborough
Bay, Tampa Bay, and Old Tampa Bay are bordered by strips of Pam-
lico terrace, which extends past Pinellas Park, but in the vicinity of
Safety Harbor, Pinellas County, the land rises 25 or 30 feet within
a quarter of a mile. Choctawhatchee Bay, East Bay, and Pensacola
Bay are likewise bordered by the Pamlico terrace. Port St. Joe is
built on the Pamlico terrace, which extends inland 10 to 15 miles.


" Agassiz, Louis, ... Florida reefs, keys, and coast; U. S. Coast Survey Rept.
for 1851.






SCENERY OF FLORIDA


COASTLINE
General features.-The east coast of Florida from the Georgia
line to Miami Beach--a distance of more than 350 miles-consists of
a series of sandy barrier islands broken here and there by inlets. For
the most part the beach is nearly straight, the most conspicuous excep-
tion being near Cape Canaveral, for several miles south of which it is
strongly curved. The sand is composed of fine grains of quartz
mixed with a variable proportion of broken shells. Where there is
little shelly matter the sand packs firmly and makes an excellent drive-
way when moist. A greater proportion of shells spoils the beach for
driving, for the shells, ground by the breakers into round fragments,
roll under pressure and permit the wheels to sink between them.
South of Miami Beach the 150-mile-long line of the Florida Keys
-long, narrow islands-curves westward to Key West and separates
the shallow waters of Biscayne Bay, Card Sound, Barnes Sound, and
Florida Bay from the deep water of the Straits of Florida. The
Marquesas Keys and some smaller islands extend the line to the Dry
Tortugas. The north shore of Florida Bay and the shore of the Gulf
of Mexico from Cape Sable to Cape Romano is very intricate, being
bordered by innumerable mangrove swamps. Such few sandy beaches
as' occur in this region are composed almost entirely of shells and
shell fragments, commonly called coral sand.
Between Cape Romano and Anclote Keys the outer shore of the
Gulf of Mexico is composed of barrier islands like those of the East
Coast but much more crooked. The beach in this region contains
many shells. Between Anclote Keys and the mouth of Ochlockonee
River there are no genuine barrier islands. The shore is very intri-
cate. There are scattered mangrove swamps at least as far north as
Cedar Keys.
At the mouth of the Ochlockonee begins a series of beach ridges
and barrier islands that extends westward beyond the State boundary
to the Mississippi Delta. They are composed of fine clean white sand,
which when dry squeaks under foot like snow. Shells are not abun-
dant. Dunes are a conspicuous feature of the landscape in this
region.
Peculiarities of the East Coast, the West Coast, and the tip of the
Peninsula.-The differences between the East Coast, the West Coast,
and the southern end of the Peninsula are caused partly by differences
in the variations of level of the Atlantic and the Gulf, partly by differ-
ences in the direction and strength of the currents along them, and
partly by the variations in the kind of materials of which the land is





S FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

composed. In general, the strip of beach laid bare at low tide is much
narrower along the Gulf than beaches of similar slope, along, the
Atlantic, for the range of tides or of other periodic .li.li "1.. of sea
level is less in the Gulf than in the ocean. There are no broad sandy
beaches on the West Coast comparable to that at Daytona Beach.
'The straightness of the East Coast, which contrasts ,with 'the
crookedness of the West Coast, appears to be the result of the greater
continuity of the currents and the more uniform drift of sand in the
Atlantic. The East Coast is swept by a southward-flowing counter
current from the Gulf Stream. Although this current, unaided, is
probably too weak to carry any but the lightest sediments, it speeds
the southward-flowing currents set in motion by the winds and retards
the northward-flowing currents. Its effect on the drift of sand along
the coast may therefore be important, for the power of running water
to transport debris is greatly augmented by an increase in velocity.
Although the direction of the drift of the sand varies with the direc-
tion of the waves, which is controlled by the winds; the pr'lin ,ig
movement is southward. The West Coast is not swept by 4 con-
tinuous current, and parts of it are not protected by barrier ii-L:.i
Moreover, the waves in the Gulf are usually smaller than those in the
Atlantic and are less effective in moving sand. The absence of bar-
rier islands between Anclote Keys and the mouth of the Ochlockonee
may be due in part to a scarcity of sand, for the streams entering the
Gulf in that region traverse an area underlain by limestone and are
fed by springs. They carry less sand and silt than many other rivers.
The peculiarities of the shore line of South Florida are due pri-
marily to the geologic composition of the region. The surface rocks-
of the mainland contain practically no quartz and have yielded little
sand to the seashore. Very little sand has drifted southward along
the coast beyond the entrance to Biscayne Bay on the east and Cape
Romano on the west. The outer arc of keys is a dead coral reef that
grew during the Pamlico epoch, when sea level was about 25 feet
higher than now. It was killed by the fall of sea level to a position
lower than the present. The existing coral reef now grows in deeper
water off shore. The Pine Islands and many other rocky islands in
Florida Bay are composed of oolitic limestone like that of the main-
land and are simply part of the same body of rock.
The innumerable mangrove swamps owe their existence to the
shallowness of the sea and to the mild climate. The long seedlings of
the mangrove tree drop into the water and float erect until they be-
come stranded in the shallows and take root. Adventitious roots let






SCENERY OF FLORIDA


down from the branches send up.new stalks, which, increase the size
of the cluster and result in the gradual coalescence of adjacent groups.
'The spreading network of mangrove roots, which extends above the
'surface of the water, affords a lodging place for flotsan ind furthers
the deposition of silt. The accumulatib of these materials causes
the water about them to become gradually shallower and shallower
until the sea bottom is finally converted into land. The mangrove i"
a tropical plant and will not tolerate much frost. Its range is there-
fore restricted to warm regions. It grows luxuriantly in southern
Florida but does not flourish far north of latitude 29.







,,;














Figure 24.-Dunes on Amelia Island near Ft. Clinch.


ISLANDS AND BEACHES

East Coast.-The northernmost of the islands along the East Coast
is Amelia Island, which extends from the mouth of St. Marys River
southward to Nassau Sound, a distance of 13 2 miles. Its greatest
width is a little more than 2 miles. The northeastern part is a long
westward-hooked sand spit studded with dunes, some as high as 40
feet, and covered with wind-twisted live oaks (see fig, 24). At the
northern end of the spit, commanding St. Marys Entrance, is old Ft;
Clinch, now a State park, whose outer walls have been partly under-
mined by the waves.





62 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

Across the half-mile-wide salt marshes of Clark Creek stand 50-
foot sand dunes (fig. 25) at the northern end of the main body of
Amelia Island, adjacent to the city and port of Fernandina. The
remainder of the island is a plain 10 to 20 feet above sea level bordered
on the east by a beadh ridge. The sand spit and beach ridge are
doubtless of Recent construction-that is, they have been built up by
the winds and waves since the ocean assumed its present level-but
the plain apparently existed as a shoal at an earlier time (Pamlico),
when the sea stood 25 feet higher.



















Figure 25.-Dunes on Amelia Island.

Amelia Island is separated from the mainland by salt marshes
ranging in width from a mile and a half to four miles, through which
wander Amelia River, South Amelia River, and other estuaries.
The six miles between Nassau Sound and the mouth of St. Johns
River is occupied mainly by Little Talbot Island, a barrier island with
sand dunes at the northern end and a long sand spit at the south.
On the south side of St. Johns River lie St. Johns Point and May-
port at the east and west ends, respectively, of a V-shaped sand spit.
The branch of the spit forming St. Johns Point is three-quarters of a
mile long. It is covered by small conical dunes between some of which
are bare damp wind-stripped shell-strewn places that seem to have
been parts of the beachleft inland by the seaward growth of the spit.
The landward end of the spit is marked by a dune-covered 30-foot
scarp overgrown with large cabbage palmettos.






SCENERY OF FLORIDA


The beach south of the spit is more than 250 feet wide at low tide.
It is bordered by an even dune ridge rising 25 to 30 feet above high
tide (fig. 26). This ridge is creeping inland across a forest of pal-
mettos, the tops of some of the tallest of which, still living, protrude
through the highest part of the ridge. Others, partly uncovered,
stand on the seaward slope. The beachward side of the ridge slopes
more gently than the landward side although it has been considerably
modified by cross winds. The landward side, about 15 feet high,
slopes at a steep angle, the angle of repose of fine sand. Back of the



















Figure 26.-Narrow dune ridge south of Jacksonville Beach, Duval County.

beach ridge there is a broken stationary ridge nearly or quite as high,
which may mark an earlier location of the beach or which may have
been blown from the present beach.
The beach extends southward unbroken for 35 miles to St. Augus-
tine Inlet. Most of it is firm, but scattered patches of shell, more
abundant toward the south, make driving hazardous. Atlantic Beach
and Jacksonville Beach near the northern end are popular summer
resorts. In winter the water is frequently colder than most people
enjoy for bathing.
South of St. Augustine Inlet lies Anastasia Island, which extends
southward nearly 14 miles to Matanzas Inlet and is separated from
the mainland by a tidal lagoon known as Matanzas River. The island
is composed in large part of parallel ridges of loosely cemented
coquina, or shell rock, rising 10 to 20 feet above sea level, separated


63





FLORIDA GEOLOGICAL SURVEY---BULLETIN SEVENTEEN


by marshy sales. The stone of which old Ft. Marion at St. Augus-
tine is built came from Anastasia Island. The coquina shows conr-
spicuous bedding planes, which dip seaward at angles like those of
modern beach deposits. This coquina seems to have accumulated as
a succession of slightly submerged bars when sea level stood 25 feet
higher than now, during the Pamlico epoch. The cementing material
is calcium carbonate derived from the shells of which it is composed.





















Figure 27.-Daytona Beach The entire area where the automobiles stand is
covered by water at high tide.


From Matanzas Inlet to Ponce de Leon Inlet, a distance of 47
miles, the beach is unbroken by inlets. The beach trends south-
southeastwardly and is nearly straight. This interval includes the
world-famous contiguous beaches of Ormond and Daytona (fig. 27),
on which automobile races are held. The beach is composed of fine
angular grains of clear quartz sand mixed with enough particles of
dark minerals to tinge it light-gray or drab. Patches of broken shells
are very rare near Daytona Beach but become more common north of
.... ....1-.-;.1 -:' ',+:,n-, 1









FiguOrm ond. The beach slopThe entire area where the gentle slope is stand is

water line from which one can wade far out at low tide. A wide
From Matanzas Inlet to Ponce de Leon Inlet, a distance of 47,
miles, the beach is unbroken by inlets, The beach trends south






southemarginal zone, neither dry land nor open weight. Thiser, interval includes there by
the waves at low tiguous beaches of Ormond and Dae.tona (fig. 27
on which automobile races are held. The beach is composed of fine
angular-grains of clear quartz sand mixed with enough particles of
dark minerals to tinge it light-gray or drab. Patches of broken shells
are very rare near Daytona Beach but become more common north of
Ormond. The beach slopes very gently, and the gentle slope is con-
tinued out to sea. The beach ridge, which borders the shore line at
extreme high tide, is 300 or 400 feet from the more indefinite low,-
.water line, from which one can wade far out at low tide.. A wide
marginal zone, either dry land nor open water, is washed over by
thie waves at low tide.


664






SCENERY OF FLORIDA


Near the Flagler-Volusia County line the coastal strip consists of
several parallel separate ridges, standing like files of soldiers, with
tops serrated by little dunes and overgrown by saw palmettos. These
ridges appear to be successively older beach ridges shut off from the
ocean by the accretion of new land. The southern part of this coastal
strip is separated from the mainland by the Halifax River, an open
lagoon, which farther north is almost closed by marshes.












,I,, M1. N....,....;"% 22






Figure 28.-Blowing Rocks, 12 miles north of Jupiter Light. The rock is hard
shell limestone, Anastasia formation, which accumulated as a submerged
bar during the Pamlico epoch. It is perforated by tubular solution cavities,
through which water spouts when storm waves strike the rock. Similar
rock is exposed at several places along the beaches between Cape Canav-
eral and Palm Beach, but it is generally covered by Recent sand.
At Ponce de Leon Inlet begins the long low barrier that, broken
only by Indian River Inlet, extends to St. Lucie Inlet, a distance of
nearly 140 miles. Opposite Titusville it bulges into False Cape and
Cape Canaveral, and encloses Merritt Island, Mosquito Lagoon,
Banana River, and Indian River. The beach ridge at many places
north of Cape Canaveral is not higher than 6 feet above high tide.
The inner side of the barrier encloses many broad marshes and
savannas. This barrier region appears to have been outlined by sub-
merged bars during the Pamlico epoch, which, when sea level attained
its present location, served as solid cores on which wind-blown and
wave-borne sand accumulated during the Recent epoch.
Jupiter Island extends 15 miles from St. Lucie Inlet to Jupiter
Inlet, continuing the south-southeastward trend of the coast line. At
most places it is considerably less than one mile wide. It, too, con-


3A-


65





FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN


tains a core of hard sandy limestone, a consolidated Pamlico bar. In
Martin County about one-quarter of a mile north of the Palm Beach
County line the ocean side of the consolidated bar has been eroded
away by the waves, and tubular solution holes in the rock spout water
when the surf rushes into them. (See figs. 28 and 29.)























Inlet nearly to Lake Worth Inlet. About 3.2 miles south of Jupiter
:i ."2 ,. . .o . .....










Light the beach ridge is 20 feet high and carries U. S. Highway 1.
The beach is steep; even at low tide the strip of shallow water ad-
jacent to the shore is very narrow. Behind the beach ridge is a low,
flat area one-quarter to one-half mile wide leading to a row of inactive
dunes firmly tied down by a thick cover of saw palmettos.
Near Lake Worth Inlet the coast line turns southward and con-
tinues nearly straight to a point about nine miles beyond Palm Beach,
whence it trends a few degrees west of south to Miami Beach. It is
broken by several inlets. Lake Worth, a lagoon, separates the barrier
from the mainland as far south as Boynton.
The municipal beach at Palm Beach is soft, steep, and narrow.
It is composed of a mixture of fine quartz sand and coarser shell frag-

ments, which prevent the sand from packing. The beach deposits are
therefore easily stirred by the waves. Wooden groynes, built to
retard and control the shifting of the sand, are packed high with sard
on the north side.and are bare on the other, showing that the prevail-


66






SCENERY OF FLORIDA


ing drift is southward. At low tide there is a narrow strip of shallow
water near shore, from which the beach rises steeply. The steepness
and softness of this beach contrasts sharply with the flatness and hard-
ness of Daytona Beach, which moreover contains fewer shell frag-
ments.




















Figure 30.-Indurated Pamlico bar or beach ridge at Boca Raton Beach.

The southward drift of sand along the East Coast is well shown
at Boynton Inlet (South Lake Worth Inlet), where sand accumulates
against the north jetty until it becomes necessary to pump it across
the inlet in order to prevent the formation of a bar across the channel.
The beach north of the inlet is actively eroding. Part of the highway
near MIanalopen (Lantana) was recently washed away.
Delray Beach is steep and contains a large proportion of shells.
At Boca Raton Beach, likewise very steep, the loose beach sand is
underlain by hard sandy yellow limestone, an indurated Pam ico bar,
which is attacked by the waves wherever the loose sand has been
washed away. Its water-worn surface affords a place of attachment
for limpets, snails, and chitons. A quarter of a mile south of the
pavilion this rock extends 20 or 25 feet above sea level. (See fig. 30.)
Its surface is gently convex. Cross-sections where it has been trun-
cated by the waves show bedding planes dipping steeply seaward.
Broken shells are more abundant than quartz in this rock, but mniost oi
the fragments are small.
The dredged harbor at Ft. Lauderdale is an important port oI
entry for pineapples, petroleum, and other products. The beaches at
"", : -. :,,-' ? ... :i;}zI'.. :.',:......::..... '",'',', : '- ., ,, ;.,. .
., .:",: ':.,..[.. . .. ,:; .. .... :--.. .. ': ...... ..... ..... ,,& : 2 ..
:o" 2 :.,, J?..... ..... . ....... -,
Figure 30 drae amic ba orbah ig a oa ao Bah
The~~~~~~~-'1 southward drif osadj'~ alngth EstCas i wllshw


'67






68 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

Ft. Lauderdale and Dania contain many coarse fragments of shells
and are soft. Hollywood Beach and Golden Beach are composed ot
finer sand and are firmer. The space exposed between tides at these
places is only 50 to 75 feet wide, but shallow water extends a con-
siderable distance beyond the low-tide zone.
The beaches north of Bakers Haulever, a dredged inlet, and at
Surfside, a suburb of Miami Beach, are steep and narrow, and are
composed of coarse loose sand containing many rounded fragments of
shells. Most of the quartz grains, also, are rounded. Miami Beach
is fairly firm. It is composed of nearly equal parts of fine shells and
quartz. It is steep, but adjoins a broad flat covered by shallow water
at low tide.
Virginia Key and Key Biscayne continue the southward trend of
the coast line 7 miles to Cape Florida at the nine-mile-wide Safety
Valve Entrance to Biscayne Bay.
Florida keys.-The main line of the Florida keys (eastern keys)
begins south of the Safety Valve Entrance and curves southwestward
in a broad arc to Loggerhead Key, a distance of almost 110 miles.
These keys are long, narrow islands covered by a dense jungle of low
trees and shrubs but containing no pines or Spanish moss. The keys
consist of an outer barrier of coral limestone sheltering inner man-
grove swamps. The highest point on the eastern keys is said to be
18 feet above sea level. Quarries in the limestone at Key Largo show
large coral heads in place, just as they grew (see fig. 11). The federal
buildings at Miami and Daytona Beach are faced with this kind of
rock. The limestone was evidently formed as a submerged coral reef
when the sea was deeper than today, for corals cannot live above
water. It presumably grew as a barrier reef during the Pamlico
epoch (late Pleistocene), when sea level was 25 feet higher than now,
was killed by the fall of sea level attending the accumulation of the
continental ice caps during the last Ice Age, and was later partly sub-
merged by the rise of the sea to its present level when those ice caps
wasted away.
The seaward side of the keys is a nearly flat sheet of limestone
that passes beneath the sea without appreciable change of slope and
with little trace of wave-cut scarp. At most places shoal water ex-
tends about 7 miles from shore. Beyond the seven-mile line the bot-
tom slopes more abruptly from depths locally as little as 2 feet to
depths greater than 100 feet. These shoals are covered in part by
living coral reefs. The landward side passes through mangrove
swamps into the very shallow water of the bays and sounds.






SCENERY OF FLORIDA


At the northern end of the chain of coral-reef eastern keys the
Ragged Keys, Sands Key, Elliott Key (nearly 8 miles long), and Old
Rhodes Key shut off the southern end of Biscayne Bay from the
Atlantic Ocean. Key Largo (28/2 miles long), partly encloses Card
Sound, Barnes Sound, Blackwater Sound, and the northeastern end
of Florida Bay. Key Largo is nearly tied to the mainland by narrow
strips of mangrove swamp, two of which carry the Over-sea Highway
and the abandoned Florida East Coast Railway to Key West.
Plantation Key and Upper Matecumbe Key extend the chain of
closely connected eastern keys about 11 miles. A gap of more than
two miles separates Upper Matecumbe from Lower Matecumbe Key,
which is nearly four miles long. At the southwestern end of Lower
Matecumbe Key is a beach of coarse "coral sand" composed of small
Foraminifera and other shells. Quartz sand is lacking at this and
other beaches on the keys.
The gap between Lower Matecumbe Key and Long Key is 3%
miles wide and 15 feet deep at the deepest place. A shallower gap of
nearly 6 miles, broken by several scattered keys, separates Long Key
from Grassy Key, the easternmost of a series of adjacent keys of
which the largest is Key Vaca, nearly six miles long, and the western-
most is Knights Key.
A seven-mile gap broken by Pigeon Key and Molasses Key
separates Knights Key from a more closely connected group 12 miles
long beginning with Duck Key and ending with Newfound Harbor
Keys. This group is connected by a prong of Big Pine Key with the
western keys, which have a different trend and foundation from the
coral-reef eastern keys. Loggerhead Key, which ends the chain of
eastern keys, lies 5 miles west of the Newfound Harbor Keys.
The western keys form a more or less compact group extending
from East Bahia Honda Key to Key West, a distance in a west-
southwesterly direction of more than 40 miles. The maximum width
of the group is about 14 miles. These keys rise from a long tongue.
like bank that underlies Florida Bay and projects westward near the
southern edge of the Floridian Plateau past the Marquesas.
The bank stands only 10 or 20 feet higher than the bottom of the
surrounding waters. It appears to have been formed as a shoal in
the sea during Pamlico (late Pleistocene) time because of the locally
more rapid accumulation of limy oolitic ooze. Further shoaling in
the sheltered waters back of the islands is probably now in progress.
11






70 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

The western keys and the bank are underlain by oolitic limestone,
which is continuous with the Miami oolite" of the mainland.
The part of the bank occupied by the western keys is crossed by
many transverse northwestward-trending shallow channels, which
divide the emerged areas into islands that trend nearly at right angles
to the chain of eastern keys. These channels are kept free of sedi-
ments by strong tidal currents, but they may have originated as drain-
age lines when the entire bank stood above water during the last Ice
Age.
The western keys consist partly of oolitic limestone, to which have
been added many accretions of mangrove swamp. The vegetation is
somewhat more varied than that of the eastern keys and includes the
patches of pine forest that -ui, -hk.1 the names of Big Pine Key and
Little Pine Key.
Big Pine Key, 8 miles long and more than a mile wide, is the
largest of the group. It lies near the western end of the group and
is connected with the eastern keys. Key West, 4 miles long and
ranging in width from a quarter of a mile to a mile and a half, is the
site of the town of the same name. The sponge fisheries, formerly
an important industry at Key West, now have their headquarters on
the mainland at Tarpon Springs, and the manufacture of cigars has
dwindled in importance. Because of the facilities for deep-sea fishing
the tourist traffic is increasing. Key West can be reached by boat oi
by automobile over the Over-sea Highway to the mainland.
Key West is without a natural fresh-water supply other than rain,
which is less copious than in other pares of Florida. Deep wells do
not yield fresh water.
West of Key West lie several scattered keys, at least one of which,
Boca Grande Key, is said to contain outcrops of oolitic limestone.
Marquesas.-The Marquesas Keys are still farther west, 18 or 19
miles beyond Key West. They form a roughly elliptical group 43/
miles long from east to west by 3/2 miles wide enclosing a shallow
lagoon whose greatest depth at low tide is 10 feet (figure 31). In
shape and manner of formation they are like the atolls of the Pacific,
but the Marquesas contain fewer fragments of corals. Like the
typical atolls, the Marquesas have a long crescent-shaped key to wind-

" Oolite is limestone composed of little spherules of calcium carbonate. It ac-
cumulates as a precipitate in shallow warm sea water.






SCENERY OF FLORIDA 71

ward (east) and, to leeward, several smaller keys that nearly complete
the enclosure of the lagoon.
The Marquesas rise from the same bank as Key West and the
other Florida keys, and are therefore presumably underlain by oolitic






,7 2 -
8 .7
8 .
. ..
5.
8. 7 .


8 10 .. ... .
3-
2'4.

55 6


.- .,:-U E .S A -S-- ..

2. O





6 46 7















Figure 31.-The Marquesas Keys, an American atoll. Part of Coast Chart, 1252.
Scale 1/80,000. Soundings in 1eet.
25 15





Figure 31.The Marquesas Keys, an American atoll Part of Coast Chart 1252
Scale 1 80 000. Soundings in feet.






72 FLORIDA GEOLOGICAL SURVEY--BULLETIN SEVENTEEN

limestone. However, according to Vaughan," the part that stands
above water level is composed entirely of detrital material, chiefly
broken shells and other calcareous organisms, heaped up and shaped
by the waves. The crescent shape of the largest island is caused by
the tendency of waves to carry sand past the ends of a cross bar and
to build it up into curved spits. The shape of this largest key, which
lies at the eastern end of the group, indicates that the prevailing winds
come from the east. The smaller enclosing keys at the western end,
which are curved in the opposite direction, presumably were built by
occasional hurricanes blowing from the west.
Dry Tortugas.-The Dry Tortugas, 60 or 70 miles west of Key
West, appear to be an atoll in the making. The part above water
consists only of a few low, scattered islands of which the largest,
Loggerhead Key, site of a lighthouse and the Tortugas Laboratory of
the Carnegie Institution of Washington, is only three-quarters of a
mile long. The islands rise from shoals that stand on a bank sub-
merged in water 40 to 70 feet deep. The easternmost shoal is bent
into a crescent about six miles across and bowed to the northeast.
The only part above water is East Key, on the southern limb. Long
Key, Garden Key (nearly covered by Ft. Jefferson), and Bird Key
lie on an irregular shoal in the southwestern part of the group. Still
farther west is Loggerhead Key, part of a five-mile-long shoal that is
gently convex towards the southeast. The lagoon within these shoals
averages between 40 and 50 feet in depth and is gradually becoming
shallower because of the deposition of limy ooze. The Dry Tortugas
are composed of detritus from calcareous organisms, among which
corals are relatively much more abundant than in the Marquesas.
Most of the coral sand is unconsolidated, but hard conglomeratic
limestone crops out on some of the beaches, notably on Loggerhead
Key, between the levels of high and low tide.
Tip of the Peninsula.-The shallow waters at the head of Florida
Bay are dotted with many little islands, most of which are merely
patches of mangrove swamp. The shore of the mainland in this
region is very crooked. Before the submergence that began the Recent
epoch, this region was a nearly level limestone plain completely bare
of quartz sand. Its surface, which sloped very gently southwestward,
was doubtless jagged, like that of the present surface of the Miami

Vaughan, T. W., Building of the Marquesas and Tortugas atolls and a sketch
of the geologic history of the Florida reef tracts: Carnegie Inst. Washington
Pub. 182 (Papers from the Tortugas Laboratory, vol. 5), pp. 55-67, 1914.






SCENERY OF FLORIDA


oolite when stripped of cover (see fig. 23). Submergence of this
plain by the rising waters of the ocean produced a very intricate
shoreline, which was further complicated by the growth of mangrove
swamps. Because of the shallowness of the surrounding water, tides
or storms that change the level of the sea cause wide temporary shifts
of shoreline.
The intricacy of the shore line is interrupted at the southwestern
end of the mainland by the smoother outlines of Cape Sable, which
appears to be a constructional feature built of successive beach ridges "
of shelly sand. North of Cape Sable the shore line is even more
intricate and reaches its culmination of complexity in the Ten Thou-
sand Islands, threaded by a maze of mangrove-bordered channels.
Back of the Ten Thousand Islands lie several shallow bays, the largest
of which, Chokoloskee Bay, 1 to 4 feet deep, is crossed by a dredged
channel 5 feet deep leading to the fishing village of Everglades.
Along part of the island-studded region between Cape Sable and
Cape Romano air-plane photographs show many little elongated man-
grove islands stretched out end to end in parallel rows all headed in
the same direction, many with a little eye-like pond at the larger end,
like schools of minnows. These islets trend southeasterly, parallel
to the general direction of the coast line. They appear to be little
bars, like magnified broken ripple marks, on which mangroves have
taken root. The uniform orientation with the larger end pointed
southeast indicates that the long-shore currents come from that direc-
tion.
West Coast.-Cape Romano lies at the southern end of a series of
nearly straight sandy beaches that extends northward about 180 miles.
Between Cape Romano and Naples, about 22 miles farther north, lie
several long barrier islands formed by southward-drifting quartz
sand and separated by Caxambas Pass, Big and Little Marco Passes,
and several other inlets. These barrier islands enclose very crooked
shallow bays and mangrove swamps. The beach at Naples, composed
of fine white quartz sand, is noted for the beauty and variety of its
shells.
From Naples the shore line extends nearly northward, curving
gently westward past Estero Bay. Este-o Island, on which is Fort
Myers Beach, is a crescent of beautiful fine white sand so firm that
one can drive along its entire length. At times, however, the beach

" Sanford, Samuel, U. S. Geol. Survey Water-Supply Paper 319, p. 49, 1913.






FLORIDA GEOLOGICAL SURVEY--BULLETIN SEVENTEEN


is foul with rotting seaweed. It is possible that in past epochs suc-
cessive accumulations of algae like those now occasionally cast up in
quantity on the shore of the Gulf of Mexico may have become, after
deep burial in mud and sand, a source of some of the great deposits
of petroleum and natural gas of Texas and Louisiana.
Carlos Bay separates Estero Island from Sanibel Island, which
projects southwesterly into the Gulf much as Cape Canaveral juts into
the Atlantic. Its northwestward continuation, Capiiva Island, is a
long narrow barrier that shuts in Pine Island Sound. Pine Island,
which lies east of the Sound, is more than 15 miles long and one to
three miles wide. It resembles the mainland in that most of it is
pine-clad. The higher parts along the west side support luxuriant
orange groves. The west shore of Pine Island is bordered by Indian
middens 20 to 30 feet high composed chiefly of conch shells.
A succession of long, narrow sandy barriers continues the north-
westward trend of the coast across the mouth of Charlotte Harbor
nearly to Venice, where it connects with the mainland. Palmetto
stumps rooted in the water and dying palmettos on the beach show
that the Gulf has recently encroached on the land at Venice, i. e. that
waves are now attacking the mainland. The bottom just off shore is
composed of peat, which probably accumulated in the lagoon behind
an island that has been washed away. The beach at Venice contains
much black sand.
From Casey Pass, the entrance to the harbors of Venice and
Nokomis, to the mouth of Tampa Bay there is a succession of long,
narrow islands trending north-northwestward and shutting off Little
Sarasota Bay and Sarasota Bay. North of Tampa Bay a sinuous line
of sandy barrier keys is separated from the Pinellas Peninsula by
Boca Ceiga Bay. This line curves around the westward projection
of the peninsula at Irdian Rocks and continues past Clearwater Har-
bor and St. Joseph Sound. A gap of 5Y4 miles separates these islands
from Anjclte Keys, opposite Tarpon Springs. All these islands ap-
pear to be of Recent origin. They have probably been heaped up by
the waves of the Gulf since the ocean assumed its present level, prob-
ably some 10,000 years ago. Clearwater Key, reached from the
mainland by a causeway and bridges, is composed of fine sand. It
rises about 6 feet above the Gulf. Its beach consists of fine clean
ouartz sand mixed with many brown and black grains.
Near the head of St. Josephs Sound the shore of the mainland
appears to have been cut into a cliff by the waves of the Gulf before
the Sound was shut off by the present barrier islands. At Clearwater






SCENERY OF FLORIDA


the old sea cliff rises about 35 feet above water level; at Dunedin it
is only 5 to 7 feet high. At Crystal Beach the land slopes rather
steeply from a height of about 5 feet to the shore, where grass passes
below tide. These shores are sandy.
Between the mouth of Anclote River and Cedar Keys the coast
line forms a broad, shallow embayment along which are the little
Indian Bay, Chassahowitzka Bay, Homassa Bay, Crystal Bay, With-
lacoochee Bay, and Waccasassa Bay. This embayment is underlain
by ancient (Eocene, Ocala) limestone, on which the cover of sand is
thin or locally absent. The shore is a broad, sinuous fringe of grassy
salt marsh broken into many islets separated by shallows. The water
in the embayment deepens so gradually that one might walk several
miles from shore in water less than waist deep.
In the bottom of the embayment are many trenches that appear to
be drainage channels made before the region was submerged. Some
of these trenches head abruptly, just as do the channels leading from
the big springs on the adjacent land. It is quite likely that these heads
mark the former location of springs, some of which may still be flow-
ing. Before the submergence that ushered in the Recent epoch the
bottom of the embayment was merely the continuation of the low
plain that borders the adjacent coast. Some of the subterranean
streams that now come to the surface at or near the present shore may
then have. emerged farther down their courses. The rise of ground
water that must have attended the rise of the sea may have forced
them to issue from the ground at higher levels.
The name Cedar Keys is applied to a group of small islands 10 to
16 miles south of the mouth of Suwannee River and to a town on Way
Key, the largest of the group. They are composed of firm white sand,
which has been heaped up by the winds and waves on a shoal that
extends into the Gulf about 17 miles from the mainland. The water
around them is very shallow but is crossed by several deeper channels.
It contains many oyster reefs. Several of the keys have the form of
atolls, irregularly curved islands partly enclosing shallow lagoons.
This shape is due to the work of currents and winds, which have
raised dunes of a height of 45 feet' on Seahorse Key, the southern-
most of the group. Mangroves are fairly common in the marshes
back of Way Key.
From Derrick Key at the northern edge of the Cedar Keys a closely
linked chain of little islands extends northward along Suwannee Shoal

1 U. S. Hydrographic Office Pub. 64, vol. 2, p. 101, 5th ed., 1907.






76 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

to a point about 3 miles beyond the mouth of Suwannee River, shut-
ting off Suwannee Sound from the Gulf. This chain appears to be a
barrier in the making. In the course of time the islets will probably
coalesce into several long narrow islands.
Between Cedar Keys and the embayed mouth of Ochlockonee
River the shore is a sinuous strip of salt marshes. It extends north-
westward about 85 miles to the mouth of Aucilla River, then curves
westward in the broad bight called Apalachee Bay, whose shoal bot-
tom is crossed by submerged channels leading from St. Marks River
and several smaller streams. These drowned channels, which give
evidence of the rise of sea level, are shown on chart 181 of the U. S.
Coast and Geodetic Survey.
South of Ochlockonee Bay and separated from the mainland by
Ochlockonee River and the tidal runways and marshes of Crooked
River lies St. James Island, which is about 22 miles long and 7 miles
wide in the widest part. Attached to the southeastern corner is a
spit that extends westward 5 miles and separates Alligator Harbor,
whose deepest point at low tide is 62 feet, from the somewhat deeper
waters of the Gulf. The village of Carrabelle is built on the western
end of the island among the sand dunes at the mouth of Crooked
River. The shore of St. George Sound northeast of Carrabelle is,
grassy.
Beyond Carrabelle the shore of the mainland extends in a nearly
straight line southwestward to East Point at the mouth of East Bay.
Excellent bathing beaches composed of clean fine white firmly-packed
quartz sand border it for several miles. They are as hard as that at
Daytona Beach, but very narrow. A low beach ridge and dunes hug
the shore and carry U. S. highway 319. St. George Sound has
recently encroached on the mainland between a point 8 miles west of
Carrabelle and East Point, for many stumps of dead pine trees, the
turpentine boxes still attached, have been undermined by the salt
water (fig. 32).
Four miles southeast of Carrabelle, across St. George Sound,
stands Dog Island, a sandy barrier nearly 7 miles long, which is
separated from St. George Island on the southwest by the shifting
channel of East Pass. St. George Island stretches 30 miles across
St. George Sound and Apalachicola Bay, whose waters are frequently
turbid from the yellow Apalachicola River. The island is a narrow
barrier built by the waves of the Gulf. A coast chart dated June,
1932, shows it continuous, but more recent maps indicate that New
Inlet, south of the town of Apalachicola, now cuts it into two separate






SCENERY OF FLORIDA


parts. The trend of the island changes at Cape St. George from
southwest to northwest.
This northwestward trend is continued by the outer shore of St.
Vincents Island, a club-shaped group of ridges and swales enclosing a
shallow lagoon at the wider, southeastern end. The island, which is
9 miles long, widens from a point at Indian Pass to 42 miles near
Apalachicola Bay. It is separated from the mainland by St. Vincents
Bay. Like Merritt Island on the East Coast, St. Vincent Island
seems to have been formed by the seaward growth of successive beach
ridges, but, like it, may contain a core of older rocks.



















Figure 32.-Shore of St. George Sound 2 miles east of the bridge over Apa-
lachicola Bay. The shore has recently been eroded back, leaving stumps
and tap roots of pine trees standing in salt water.
Part of the sand of which St. Vincent Island is built may have
been cast up by the waves from the adjacent floor of the Gulf; the
remainder may have been eroded from the tip of the mainland (part
of the delta of Apalachicola River) west of Indian Pass. The shore
of the Gulf in this region is an even arc evidently shaped by the waves.
From the mainland the narrow Indian Peninsula projects 3 miles
eastward across Indian Lagoon, and a sandspit projects 4 miles west-
ward to Cape San Blas. This part of the spit appears to be increasing
in width by accretion on the Gulf side. The bare sand between the
beach and the several rows of dunes is perhaps 1000 feet wide. At
Cape San Blas the spit turns sharply north-northwestward and con-
tinues 17 miles to St. Joseph Point, curving gradually toward the
northeast near the tip.


77






78 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

This spit nearly encloses St. Joseph Bay, an excellent harbor 20
to 35 feet deep on which is the growing town of Port St. Joe. The
head of the bay is much shallower. The mainland shore of St. Joseph
Bay south of Port St. Joe has recently been eroded. Stumps of pine
trees stand in the salt water as much as 100 feet from shore.
From Port St. Joe the shore of the mainland curves northwest-
ward. Fifteen miles from the town the long sand spit named Crooked
Island forks off and continues 10 miles along St. Andrews Sound. As
seen across the sound, Crooked Island shows as a low white line from
which rise high sand dunes, like snow-capped peaks above a sea of
cloud.
Between the entrances to St. Andrews Bay and Choctawhatchee
Bay the coastline forms part of the great arc that extends from Cape
San Bias to the Alabama line. The trend in this region is west-
northwestward. A twelve-mile-long spit, broken at several places,
has been built southeastward along St. Andrews Bay, and a peninsula
26 miles long extends west-northwestward south of Choctawhatchee











.... .......








Figure 33.-Panama City Beach.

Bay. The beaches in all this region are clean white sand (figs. 33
and 34). The sand south of Choctawhatchee Bay squeaks under foot.
The shore of the Gulf between East Pass, at the mouth of Choctaw-
hatchee Bay, to the entrance to Pensacola Bay, a distance of nearly
52 miles, follows Santa Rosa Island, a narrow barrier of fine white






SCENERY OF FLORIDA


sand dotted with large sand dunes (figs. 34 and 35). Behind it is
Santa Rosa Sound, a lagoon tapering in width from 2 miles near the
western end to less than a quarter of a mile in The Narrows at Fort


Figure 34.-The dune ridge west of Panama City Beach.


Figure 35.-Dunes on Santa Rosa Island 5 miles east of Camp Walton.

Walton, near the eastern end. A similar dune-covered narrow island
extends west-southwestward in line with Santa Rosa Island and partly
barricades the entrance to Perdido Bay, through which passes the
boundary line between Florida and Alabama.


79


:s~ p ,~ ~~






80 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

LAGOONS AND BAYS

The entire East Coast of Florida is bordered by a once-continuous
series of lagoons, which is followed by the Intracoastal Waterway.
North of Jacksonville the lagoons have the form of broad salt marshes,
through which wander crooked tidal rivers. This northern part of
the coast is the continuation of the Sea Island region, which extends
northward to Charleston, S. C. South of Jacksonville the lagoons
run parallel to the coast, and many of them are broad and open.
The lower part of St. Marys River, all of Nassau River, and the
St. Johns below Jacksonville pursue very tortuous courses eastward
to the Atlantic through tidal marshes. They are connected by open
runways through the marshes' behind Amelia Island and Talbot Island.
Pablo Creek, which enters the St. Johns just above Mayport, is
a tidal channel through marshes. The southward continuation of
these marshes connects with the head of North River, which leads
southward to an inlet at St. Augustine. Matanzas River, a narrow
lagoon, conducts the Intracoastal Waterway from St. Augustine to




















Figure 36.-Tomoka Creek, a tidal river 4 miles north of Ormond.

Matanzas Inlet, near which the Waterway enters a canal leading to
Halifax River. Halifax River (fig. 37), a straight lagoon about
three-quarters of a mile wide, passes Ormond and Daytona Beach.
At Ponce de Leon Inlet, it connects with Mosquito Lagoon, a broader,
island-dotted expanse, which terminates near False Cape. Banana






SCENERY OF FLORIDA


River, a wide, curved lagoon back of Cape Canaveral, connects at both
ends with Indian River. The two lagoons enclose Merritt Island.
Indian River is the longest and one of the straightest lagoons in
Florida.. It extends from a point about 13 miles north of Titusville
to St. Lucie Inlet near Stuart, a length of nearly 120 miles. It is
widest (about 5 miles) near the northern end, where a short passage
connects it with Mosquito Lagoon, and a longer, crooked channel
passes around the northern end of Merritt Island to Banana River.
Its" average width is about 2 miles. It is narrower and much ob-



















Figure 37.-A glimpse of the Halifax River, a lagoon, through palmettos at
Ormond.

structed by marshy islands between Sebastian and Vero Beach.
Indian River is deepest between Cocoa and Melbourne, where a depth
of 10 feet is common, and depths of 15 feet are rarely attained. Tidal
currents have scoured the narrow channel connecting it with the south
end of Banana River to a maximum depth of 27 feet.
Narrow passages through mangrove swamps connect the south end
of Indian River with Hobe Sound and Jupiter Sound, which lead to
Jupiter Inlet. A dredged channel through Lake Worth Creek and
tidal marshes connects Jupiter Sound with Lake Worth, which
separates Palm Beach from the mainland and extends to Boynton.
Lake Worth is a straight lagoon about 22 miles long and generally
about half a mile wide. A dredged channel across Lake Worth Inlet
leads to the artificial Port of Palm Beach.


81






FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN


The Intracoastal Waterway south of Lake Worth leads through
marshes and tidal creeks to the head of Biscayne Bay. At Fort
Lauderdale it passes the important artificial harbor of Port Everglades,
which serves an increasing volume of ocean-borne commerce.
The upper part of Biscayne Bay, between Bakers Haulover and
the dredged ship channel at Miami, is a shallow lagoon three miles
wide in places and generally less than 5 feet deep. South of Miami,
the bay widens to 6 miles at Cape Florida, where it opens into the
Atlantic, and its southern part is even wider. The depth in the central
region is around 9 to 12 feet. Card Sound, Barnes Sound, and Black-
water Sound, all back of Key Largo, are about the same depth.


















Figure 38.-Santa Rosa Island from the mainland, near Camp Walton, looking
across Santa Rosa Sound.
Whitewater Bay and other charted mangrove-enclosed water
bodies around the tip of the Peninsula do not exceed four or five feet
in depth. Chokoloskee Bay at Everglades, though larger, is even
shallower. These and many other smaller bodies of salt water south
of Naples appear to have been separated from the open waters of
Florida Bay mainly by the growth of mangroves.
North of Naples most of the estuaries have been enclosed by the
growth of barrier islands and are generally somewhat deeper. Estero
Bay lies behind Big and Little Hickory Island and Estero Island.
Pine Island Sound, whose greatest depth is 9 feet, is nearly enclosed
by Sanibel Island, Captiva Island, and Lacosta Island, but connects at
the south with San Carlos Bay at the mouth of Caloosahatchee River,
and opens at the north into, Charlotte Harbor, the drowned mouth of


82






SCENERY OF FLORIDA


Peace Creek. Depths of 23 feet are exceptional in Charlotte Harbor,
but soundings of 55 and 65 feet are charted at its entrance. These
excessive depths apparently are due to scour, for the depth of the Gull
at Boca Grande is only about 40 feet.
Gasparilla Sound opens broadly into Charlotte Harbor but nar-
rows northward into Placid Harbor, which connects by a narrow creek
with Lemon Bay, a long narrowing lagoon terminating near Venice.
Little Sarasota Bay, beginning at Venice Inlet, leads into Sarasota
Bay, which attains a width of four miles and a maximum depth of 12
feet.
Tampa Bay, which is 10 miles wide at St. Petersburg, contains
a 2-mile-wide channel 20 to 30 feet deep, which is the drowned flood-
plain of Hillsborough River. This channel, gradually shallowing,
extends up Hillsborough Bay to Tampa. Old Tampa Bay, which is
crossed by the Gandy Bridge and the Tampa-Clearwater Causeway,
has a maximum depth of 17 feet. Exceptional soundings of 81 ana
93 feet in Egmont Channel probably indicate scour. Boca Ciega Bay,
a very shallow northward expansion of Tampa Bay, is crossed by
several deeper channels. Clearwater Harbor and its northward ex-
tension, St. Joseph Sound, are only partly enclosed by several long
sandy islands.
There are no notable lagoons along the Gulf Coast between the
entrance to St. Joseph Sound and Franklin County, where Dog Island
and St. George Island partly shut off St. George Sound. Apalachicola
Bay, East Bay, and St. Vincents Sound, which lie at the end of the
delta of Apalachicola River, are more nearly enclosed by islands.
St. Josephs Bay, St. Andrews Sound and Santa Rosa Sound (fig.
38) are parts of the Gulf of Mexico, from which they were separated
by the comparatively recent growth of spits and barrier islands. St.
Andrews Bay, North Bay, and West Bay appear to occupy shallow
valleys eroded by streams during the last (Wisconsin) glacial stage
and flooded by a rise of sea level. Choctawhatchee Bay, likewise, is
the drowned mouth of Choctawhatchee River, which is extending its
delta into the bay. Its depth ranges from 9 feet near the delta to 40
feet in the lower reaches, but its narrow passage to the Gulf is kept
shoal by drifting sand (see fig. 39).
Pensacola Bay, with its branches East Bay and Escambia Bay,
represents a large drowned river valley formed by the confluence of
the Yellow, the Blackwater, and the Escambia. Each of these streams
is building a delta at the head of its respective branch, but the lower







84 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN


part of the bay still retains depths of 30
through which passes the Alabama-Florida
lower mouth of a smaller river.


to 40 feet. Perdido Bay,
boundary line, is the shal-


H-i'A
.'


; ..,q :


Figure 39.-Hooked spit at entrance to Choctawhatchee Bay.


A7~i~


Figure 40.-View from Valparaiso, Okaloosa County, down Boggy Bayou to
Choctawhatchee Bay.






SCENERY OF FLORIDA


HARBORS

The harbors of all the world occupy basins that have been deepened
by the rising sea level that attended the melting of the last great con-
tinental ice sheets. The harbors of Florida are no exception. They
differ from those of some other regions, however, because of differ-
ences in the topography of the land before the advance of the sea upon
it.
Many great harbors occur in regions that were hilly or moun-
tainous or which were trenched by deep valleys. Thus New York
Harbor lies in the valley of the Hudson, a deep trench, which has been
traced far out to sea. Similarly, the harbors of Baltimore and Nor-
folk occupy branches of the drowned valley of the Susquehannah,
which was cut deep into the upland. The southwest coast of Alaska
and the fiords of Norway are familiar illustrations of drowned moun-
tainous regions.
But there were no mountains or deep valleys in Florida. The
surface of the Floridian Plateau laid bare by the retreat of the sea
during the last Ice Age and submerged again at its close was a very
gently sloping plain across which the streams flowed in very shallow
valleys. If the shore line during the last Ice Age lay on the steeper
slope at the edge of the Plateau, the streams may have cut trenches at
its outer margin, but, if so, the trenches did not extend inland as far
as the present coast. It thus happens that there are no very deep
harbors in Florida. Their depth is no greater than the normal depth
of large rivers flowing over soft bottoms.
The only natural deep harbor on the Atlantic coast of Florida is in
the St. Johns River at Jacksonville, the controlling depth of which is
30 feet. Occasional dredging is required to maintain the channel if
the lower courses of the river, but the narrows at the city are kept
deep by tidal scour. A dredged channel across Indian River permits
ships of 24.5 feet draught to reach Fort Pierce from the ocean through
Fort Pierce Inlet. The controlling depth from the Atlantic to Port
Sewell through St. Lucie Inlet in 1938 was 5 feet. This channel will
ultimately be deepened to 18 feet.
The controlling depth through Lake Worth Inlet to the port of
Palm Beach is 20 feet. Hollywood Harbor (Port Everglades) had
been deepened by 1938 to 30.4 feet; the projected depth is 35 feet.
The controlling depth of the dredged channel from Miami through
Biscayne Bay to the ocean is 30 feet.






86 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

Key West, on the Straits of Florida, is approached by a main ship
channel 30 feet deep, with a depth of 26 feet opposite the wharves.
The northwest channel is only 17 feet deep.
Ft. Myers, on Caloosahatchee River 19.3 miles from the Gulf, can
be reached by boats of 9.5 feet draught, and boats drawing 6 feet can
pass through canals and Lake Okeechobee to the Indian River near
Stuart. The ship channel to South Boca Grande, at the south end of
Gasparilla Island, has a minimum depth of 27 feet, but the controlling
depth in Charlotte Harbor to Punta Gorda is only 10 feet. Sarasota
can be reached by boats drawing 7 feet from either Tampa Bay or
through New Pass Channel.
Tampa, an important port; can be reached by ships drawing 30
feet. The entrance channel from Tampa Bay to St. Petersburg
admits vessels drawing only 11.6 feet.
There are no deep harbors between Tampa and St. Josephs Bay,
but boats drawing 10.5 feet can reach Cedar Keys, and smaller ves-
sels can find sheltered anchorage at several places. St. Josephs Bay,
shut off from the Gulf by a long sand spit, would shelter a large fleet.
Its controlling depth is 27 feet. The only harbor facilities are at Port
St Joe, the terminus of a railroad and the site of a large paper mill.
St. Andrews Bay is smaller, but ships of the same draught can reach
Panama City.
Although there is ample deep water within Choctawhatchee Bay,
the controlling depth to it through East Pass is only 6 feet. Vessels
drawing 9 feet can enter it through Santa Rosa Sound, which carries
the Intracoastal Waterway.
The controlling depth to Pensacola Harbor, the most important
port in West Florida, is 30 feet. The Federal Government maintains
a Navy Yard and a Naval Air Station near Pensacola.

RAINFALL
The source of all the fresh water that is drawn from wells or that
flows out of the ground as springs or that stands on the surface as
lakes is rain. Florida is plentifully supplied with rain. The average
annual precipitation is about 52.7 inches-enough to flood the entire
land breast deep if none soaked into the ground, ran off, or evaporated.
The rainfall of Florida is not uniformly distributed throughout
the year nor do all parts of the state receive the same amount. The
most abundant precipitation is in the southern part of the Peninsula,
where heavy tropical downpours during the summer months swell the






SCENERY OF FLORIDA


normal total to 65.7 inches at Homestead. At Key West, the normal
precipitation is only 38.1. inches, but the rainfall is more evenly distri-
buted throughout the year. In general, more rain falls throughout
the state during the summer than in the winter, and this seasonal dif-
ference is most pronounced in the southern part of the Peninsula.

GROUND WATERS
Because of the prevailingly loose, sandy sdil, much of the rainfall
of Florida sinks into the ground and is stored up in the great reservoir
of ground water. When Florida emerged from beneath the sea it was
thoroughly saturated with salt water, whose normal level is sea level.
Rainwater, accumulated above it, floats on this heavier, ancient sea
water and presses it down below sea level. Theoretically, for each
36 feet that the accumulated store of fresh water depresses the top of
the zone of salt water below sea level, fresh water will stand one foot
above sea level,'for 36 cubic feet of sea water weighs about the same
as 37 cubic feet of fresh water. Actually, the boundary between fresh
and salt water is somewhat indefinite, for there is some mixture at
the contact. Moreover, the fresh and salt water may not everywhere
stand in hydrostatic equilibrium, for the permeability of the rocks that
serve as reservoir is irregular and may be locally too slight to permit
rapid' readjustment with changes in pressure.
Every rain adds to this store of fresh ground water, but the supply
is constantly being depleted by springs and by seepage into the ocean.
During the many years in which these processes of natural addi-
tion and subtraction have been going on, a condition approximating
equilibrium has been reached. The loss over a period of years equals
the intake during the same time, and the surface of the saturated zone,
called the water table, fluctuates about a mean position.
During the last few decades, however, the growth of large cities.
many of which withdraw great quantities of water from the under-
ground reservoir, has introduced a disturbing factor. The intake no
longer equals the outflow. The local water table will inevitably be
lowered or the artesian pressure will be decreased until a new and
lower position of equilibrium becomes established.
In many parts of the state, this lowering, pf the water table or
decrease in the artesian pressure may not be of much importance to
the welfare of the inhabitants; but elsewhere, particularly in coastal
or low-lying regions, it may become a serious problem. In some
coastal regions the depth to salt water is not great because the fresh
ground water above it can not rise high enough above sea level to






88 FLORIDA GEOLOGICAL SURVEY--BULLETIN SEVENTEEN

depress it far. This salt water is free to move about under ground
through pores and cavities in the rock or sand and may be added to by
seepage from the ocean. If the water table above it is lowered 1 foot
by pumping, salt water rises about 36 feet and may contaminate the
well.
Except in very permeable or cavernous rocks such as the Ocala
limestone, where it is nearly level, the water table conforms to the
major topographic features, being higher under hills and not so high
under valleys. Its shape is a much-smoothed and generalized reflec-,
tion of the surface of the ground. In well-watered, poorly drained
regions the water table frequently rises above the surface of the
ground and coincides with the surface of ponds and lakes. Valleys
containing permanent streams cut below the surface' of the ground
water, which seeps out at or below the water table or issues through
more or less well defined channels, called springs.

SPRINGS
The springs of Florida fall into two well-defined classes, seepage
springs and artesian springs. Seepage springs are those in which the
water seeps or flows through channels everywhere higher than the
outlet. ,Ir t.hi tl,,- ro:,oii!,, t tif, .f .[ i,, _*;ur: !,.- .viler
is local eepagesprings form wherever the ground stands lower than
the water table and the soil is sufficiently permeable to permit water
to escape. In artesian springs the water comes from a distant source
through underground channels that lie at a lower level than the outlet,
and which therefore form inserted siphons. Such springs appear to
require special and unusual conditions to come into existence. Seep-
age springs and artesian springs' ,are alike in that the ultimate source
of the water is rain that sinks into the ground at a level higher than
the outlet.
Most of the large spi iL- of Fl, ridla arec :rtesian. The water flow-
ing from them rises through deep, generally vertical holes in lime-:
stone, some of which holes extend more than one hundred feet below
sea level. At the bottom these holes open into caverns, presumably
nearly horizontal, through which flow underground rivers.
SThe formation of open, continuous caverns so far below the pres-
ent water table seems to require more active circulation of under-'
ground water than is possible through solid rock under present con-
ditions. Water seeping through porous limestone becomes progres-
sively more saturated with calcium carbonate and can dissolve no more'
rock-until it has been replaced by fresh supplies. Water lying below






SCENERY OF FLORIDA


the water table and therefore under hydrostatic pressure is generally
nearly stagnant unless there are open caverns through which it can
move. The growth of caverns takes place most rapidly above and
along the water table, where the newly arrived water contains least
mineral matter in solution and therefore is most actively solvent.
Once formed, however, caverns may continue to conduct unsaturated
water and to grow in diameter even though the water table may have
risen to a much higher level, for the descending freshly absorbed rain-
water finds access to them through vertical channels etched during an
earlier epoch.
The cavity through which water ascends to an artesian spring is
generally a former sink in which the direction of motion of the water
has been reversed by the rise of the water table. If the water table
were to fall below the mouth of the cavity, the spring would cease to
flow and would revert to the form of a sink, provided that the tubular
cavity leading to the spring does not penetrate an impervious stratum,
which might confine the water below it under pressure. (See figure
41.)

FEET
100
ry


-bo
Silver Rlun I I
Scturated -







cavernous limestone through active sinks, flows through caverns, and emerges
through sinks that have been submerged by a rise of the water ttble. The
vertical scale is much exaggerated.





As some artesian springs rise from depths well below sea level,
they presumably corroborate other evidence that sea level has risen.
The depth to which the covers extend below sea level appears to give


a minimum measure of after system of an sea level has ris en singers the
cavern s w er e formed thru is active sinks, should d b e added the orgies
additional height of the water table caused by a rise of the greater distance of
vertical scale is much exaggerated.

As some artesian springs rise from depths well below sea level,
they presumably corroborate other evidence that sea level has risen.
The depth to which the caverns extend below sea level appears to give
a minimum measure of the amount that sea level has risen since the
caverns -were formed To this amount should be added the original
additional height of the water table caused by the greater distance of
the spring, then a sink, from the seashore--a quantity that can only be
estimated.


4-






90 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

Salt Spring.--Some caverns that extend below sea level lie below
the zone of fresh water. Springs fed through these inverted siphons
may become contaminated with salt water from the surrounding porous
limestone and may yield saline water.. This seems to be the source of
the salt in Salt Spring (see fig. 42), Marion County, whose water has











.. ...







Figure 42.-Salt Spring, Marion County. An artesian spring whose water is
contaminated by passing through caverns in rock saturated with salt water.

the composition of diluted sea water. Salt Spring lies near sea level
on the north shore of Lake Kerr at the eastern edge of the Central
Highlands. It issues from clefts in sandy limestone of the Hawthorn
formation. Some of the fissures appear to be at least 30 feet deep.
Silver Springs.-Within the Central Highlands are several very
large springs. The flow of Silver Springs (see fig. 43), 6 miles east
of Ocala, is believed to be the largest of any group of limestone springs
in the United States, although it is exceeded by springs issuing from
volcanic rock along Snake River in Idaho. The discharge of Silver
Springs, as measured five times by the U. S. Geological Survey, ranges
from 342 to 822 second-feet, the last equivalent to 22,134,816 gallons
per hour."6
Silver Springs issue from several submerged cavities in the Ocala
limestone. The largest cavity is Big Spring, whose aperture measures
65 feet by 12 feet, and whose depth is 41 feet. The Bridal Chamber,
" Meinzer, 0. E., Large springs in the United States: U. S. Geol. Survey Watel"-
supply, Paper 557, p. 12, 1927.











~~iw:

bIIN.


Figure 43.-Bird's-eye view of Silver Springs. Photograph by courtesy of the proprietors.






92 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

a narrow rocky cleft, has been sounded to a depth of 81 feet." The
bottom of Silver Springs Run is covered by long grass except in the
springs, in which the rock is bare or covered by an accumulation of
white shells of Ampullaria and other fresh-water snails. The tem-
perature of the water is 73-74 F." The water is colorless and so
transparent that one can see and photograph through the floor of a
glass-bottomed boat all the details of the deepest springs.
Silver Springs appear to have originated as a series of sink holes
along the course of an underground stream at a time when the water
table stood at least 80 feet lower than now, presumably during the last
glacial stage, when sea level may have been as much as two or three
hundred feet below its present position. Rise of the water table above
the mouth of the sinks has caused them to overflow and converted
them into springs. Lowering of the water table by a few feet would
stop their flow. The ultimate source of the water in the springs is
rain, which, falling on the highlands of central peninsular Florida,
seeps down through the sand into cavities in the Ocala limestone and
follows them underground, perhaps for many miles, before emerging,
crystal clear, in Silver Springs. (See fig. 41.)
Rainbow Spring.-Blue Spring (see figs. 44, 45), also called Rain-



















Figure 44.-Rainbow Spring, an artesian spring forming the head of
Wekiva Creek.

17 Mr. W. C. Ray, one of the proprietors, is the authority for these measure-
ments.
18 Stringfield, V. T., Artesian water in the Florida Peninsula: U. S. Geol.
Survey Water-Supply Paper 773-C, p. 155, 1936.





SCENERY OF FLORIDA


bow Spring, at the head of Wekiwa Creek 4 miles north-northwest of
Dunnellon, is similar in origin to Silver Springs, but the orifices
(visible through glass-bottomed boats) are more densely overgrown
by vegetation, and sand is much more abundant. Some of the springs
boil through sand. The springs near the head of the creek are said
to range from 30 to 50 feet in depth, but Garfish Hole, about 1 mile
down stream, is reported to be about 60 feet deep. Four measure-
ments of the flow of Wekiwa Creek range from 716 to 847 second-
feet. The temperature is reported to be 74 F."1



















Figure 45.-View down Wekiva Creek from Rainbow Spring.

Weekiwachee Spring.-Weekiwachee Spring, in Hernando County
12 miles west of Brooksville, boils up from a depth of about 145 feet
into a basin about 130 feet across. The temperature is reported to be
780 F., and the measured flow varies from 106 to 251 second-feet."2
The caverns that supply it doubtless ramify through the Ocala lime-
stone, although the orifice presumably penetrates the Suwannee lime-
stone, The stream running from it flows into the Gulf of Mexico,
12 miles away.
Spring at Hudson.--A spring said to be 60 feet deep issues from
white limestone near the shore of the Gulf at Hudson, Pasco County,
and forms a harbor for small boats. The water is clear but somewhat
brownish. This spring may penetrate through the Suwannee lime-
stone into the Ocala.
l Meinzer, O. E., op. cit., p. 11.
* Stringfield, V. T., op. cit., pp. 155 and 157.


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94 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

Homosassa Spring.-iHomosassa Spring, one of the sources of the
Homosassa River, in Citrus County, is reported to be 100 feet deep.
It issues from the Ocala limestone. It is remarkable for the large
fishes that swim in its clear waters.
Crystal River.-Crystal River, in Citrus County, heads in large
springs, which are used as harbors (see fig. 46).



















Figure 46.-One of the springs forming the head of Crystal River, Citrus
County. The growth in the foreground consists of blooming water hya-
cinths, which float on the water and greatly impede navigation.

Springs near th2 Gulf Coast.-The springs at Hudson, Homosassa,
and Crystal River are only a few of the many along the Gulf coast
that flow from the Ocala, Suwannee, or Tampa limestones between
Cedar Keys and Clearwater. Most of these springs are artesian.
Their source is the rain that falls on the land east of them, passes
downward through sink holes to ancient caverns that lie below the
present water table, and emerges through vertical passages at sea level'
where their way is blocked by sediment or sea water. The caverns
that feed them may extend seaward beyond the present shore far out
beneath the floor of the Gulf of Mexico.
Juniper Spring.-Juniper Spring (fig. 47), in the Ocala National
Game Refuge 4 miles west of the Marion-Lake County line on State
highway 19, is maintained by the Forest Service as a public picnic and
camp grounds. The clear, cold water boils up through several aper-
tures in the Ocala limestone. The level is held about 5 feet above
normal by a dam, which diverts the water under a mill wheel.






SCENERY OF FLORIDA


Silver Glen Spring.--Silver Glen Spring (fig. 48), in Marion
County near the Lake County line 6 miles north of State highway 19,
contains two or more boils, one of which is in the middle of the wide
head of a creek. Another comes through an elliptical hole about 10
feet in larger diameter and said to be about 30 feet deep. It forms a
tributary stream about 100 feet long. The water is colorless and very
transparent. Around the spring are large Indian mounds composed


Figure 47.-Juniper Spring in the Ocala National Game Refuge.


Figure 48.-Silver Glen Spring, Marion County.


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96 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN

of shells of Ainplllaria and other fresh-water snails, and containing
also human skeletons, bone, shell and stone implements, and pottery.
Silver Glen Spring lies at the eastern edge of the Central Highlands
three-quarters of a mile west of Lake George.
Alexander Spring.-Alexander Spring, in Lake County 5 miles
south of Astor Park, gives rise to a creek comparable in size to Silver
Springs Run. It is tributary to St. Johns River. The main boil
comes through a deep sinklike hole beneath a large ledge of rock,
presumably the Ocala limestone. As the water stands about 10 feet
above sea level, the cavern must lie considerably below sea level. The
spring, which lies within the Ocala National Forest, is surrounded by
very tall cypress and cabbage-palmetto trees and a mixed growth of
other forest trees. Its surroundings are entirely natural except for a
rickety board walk, which projects out from the swampy shore to the
edge of the main boil.



















Figure 49.-Itchatucknee Spring, Suwannee County.

Orange Spring.-Orange Spring, from which the village of Orange
Springs at the north edge of Marion County is named, is much
smaller than the other springs herein described. It differs from them,
too, in that its water contains sulphur. No chemical analysis is neces-
sary to attest this fact, for the odor of hydrogen sulphide is plainly
evident. The spring flows through sand into the bottom of a circular
pool enclosed within concrete walls, which raise its level about 3 feet.
It is surrounded by tall pines and cabbage palmettos. The water pre-
sumably is derived from the Hawthorn formation, which yields sul-
phur water at a number of places.






SCENERY OF FLORIDA


Green Cove Springs.--The spring from which Green Cove Springs,
Clay County, takes its name issues from a vertical pit, said to be 40
feet deep, which narrows downward like a sink hole. The rock ap-
pears to be sandy limestone, probably Hawthorn formation. The
temperature of the water is reported to be 78 F., and the flow 3,000
gallons per minute. The water yields a strong odor of hydrogen
sulphide.
White Springs.-White Springs, on the right bank of Suwannee
River in Hamilton County, likewise yields sulphur water. The water
issues either from the Hawthorn formation or at the contact of the
Hawthorn and the Suwannee limestone. The spring is enclosed in a
bathhouse. In April, 1937, the spring was submerged by a 22-foot
rise of the river, which completely stopped its flow and apparently
converted it into a sink. There are other sulphur springs along
Suwannee River, notably Suwannee Springs, north of Live Oak.
These springs are probably all normal seepage springs, that is, the
subterranean channels through which they flow are little, if any,
deeper than the springs themselves.



















Figure 50.-Wakulla Spring, said to be 185 feet deep.
Itchatucknee Spring.-Itchatucknee Spring (fig. 49), about 3 miles
northeast of Hildreth, Suwannee County, issues as a strong boil
through the Ocala limestone. Near by a small surface spring enters
through a cavern at water level. The spring heads a creek, which
forms the county line for four or five miles to its junction with the
Santa Fe. Itchatucknee is one of the larger springs of Florida. Its
flow is reported as more than 400 second-feet, and its temperature
74 F.


4 A --


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98 FLORIDA GEOLOGICAL SURVEY-BULLETIN SEVENTEEN





4sI-i
i i


; Figure 51.-Wakulla River at US 319. Its source is Wakulla Spring.






SCENERY OF FLORIDA


Wakulla Spring.-One of the largest and deepest single springs in
Florida is Wakulla Spring in Wakulla County south of Tallahassee
(figs. 50, 51). The water rises from beneath a thick ledge of lime-
stone into a pool reported to be 185 feet deep. It carries in suspension
minute particles, possibly sulphur, which are so small that they are
visible only in deep places, where they resemble motes floating in a
sunbeam. Several mastodon skeletons have been recovered from
shallow places around the margin. One of them is now in the Geo-
logical Survey Museum at Tallahassee. The temperature of the
water is reported to be 70 F., and the flow has been estimated at 326
second-feet.
Sulphur springs.-Many springs issuing from the Tampa lime-
stone and the Hawthorn formation yield sulphur water. Among
them may be mentioned Sulphur Spring at Tampa, Lithia Sulphur
Spring in Hernando County, Wekiva Spring in Orange County, Kis-
sengen Spring in Polk County, Palm and Sanlando Springs in Seminole
County, and Zolfo Springs in Hardee County. Hampton Springs in
Taylor County apparently issues from the Suwannee limestone.

Other Springs.---Other springs worthy of note are Poe Spring in
Alachua County, the springs at the head of Wacissa River in Jefferson
County, Blue Spring in Jackson County, Troy Spring in Lafayette
County (fig. 52), Bugg Spring in Lake County, and Ponce de Leon
Spring in Volusia County (fig. 53).


Figure 52.-Troy Spring, Lafayette County, Suwannee River in the background.


99