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Geology of the state parks in the Florida Keys ( FGS: Leaflet 14 )
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Title: Geology of the state parks in the Florida Keys ( FGS: Leaflet 14 )
Series Title: ( FGS: Leaflet 14 )
Physical Description: Book
Creator: Lane, E.
Publisher: Florida Geological Survey
Publication Date: 1968
 Subjects
Subjects / Keywords: Florida Keys (Fla.)
Spatial Coverage: Florida -- Florida Keys
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Source Institution: University of Florida
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Table of Contents
    Title Page
        Page i
        Page ii
        Page iii
        Page iv
        Page v
    Table of Contents
        Page vi
    List of Figures
        Page vii
    Acknowledgement
        Page viii
    Geology of the state parks of the Florida Keys...
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
        Page 29
        Copyright
            Copyright
Full Text







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

DIVISION OF RESOURCE MANAGEMENT
Art Wilde, Director

BUREAU OF GEOLOGY
Walter Schmidt, Chief







Leaflet No. 14

GEOLOGY OF THE STATE PARKS
IN THE
FLORIDA KEYS

by

Ed Lane


Published for the
FLORIDA GEOLOGICAL SURVEY
TALLAHASSEE
1986




























































ii











DEPARTMENT
OF
NATURAL RESOURCES


BOB GRAHAM
Governor


GEORGE FIRESTONE
Secretary of State

BILL GUNTER
Treasurer

RALPH D. TURLINGTON
Commissioner of Education


JIM SMITH
Attorney General

GERALD A. LEWIS
Comptroller

DOYLE CONNER
Commissioner of Agriculture


ELTON J. GISSENDANNER
Executive Director























































iv
















































Printed for the
FLORIDA GEOLOGICAL SURVEY
Tallahassee
1986






v.








TABLE OF CONTENTS

Page
Acknowledgements ...................................... viii
Geological History ........................................ 1
Environment .......................................... 5
State Parks
Visitors' Information ................................. 15
John Pennekamp Coral Reef State Park ................. 15
Lignumvitae Key State Botanical Site ................... 18
Indian Key State Historical Site ........................ 20
Long Key State Recreation Area ........................ 21
Bahia Honda State Recreation Area ..................... 24
Selected Bibliography .................................... 28











FIGURES


Figure Page
1 Map of the Florida Keys, showing State parks and extent
of the Key Largo Limestone and the Miami Limestone ... 2
2 Oblique view of the Floridan Plateau .................. 4
3 Mangrove trees, showing thickly tangled prop roots...... 8
4 Mangrove seedlings in the process of colonizing a shallow
lime-mud bank ................................... 9
5 Aerial view of part of John Pennekamp Park ........... 10
6 Gumbolimbo tree .................................. 11
7 Florida Poisontree ................................ 11
8 West Indies Mahogany tree ......................... 12
9 Mastic tree ................. ..................... 12
10 Jamaica Dogwood ................................ 13
11 Pigeon Plum tree ................................. 13
12 Florida Strangler Fig ............................... 14
13 Lignumvitae tree ................................. 14
14 John Pennekamp Coral Reef State Park, showing points
of interest on the reef tract ....... ................. 16
15 Map of John Pennekamp Coral Reef State Park ........ 17
16 Map of Lignumvitae Key State Botanical Site and Indian
Key State Historical Site ........................... 19
17 Aerial view of Indian Key ........................... 22
18 Map of Indian Key showing archeological sites.......... 23
19 Ocean-facing beach at Long Key showing erosion ....... 25
20 Map of Long Key State Recreation Area ............... 26
21 Map of Bahia Honda State Recreation Area ............ 27










ACKNOWLEDGEMENTS


The author gratefully acknowledges the assistance of the following
Rorida park personnel for the information and photographs that they
provided: Dr. Renate Skinner, Major Russell Danser, Mark Yelvington, and
Larry Gavagni.






LEAFLET 14


GEOLOGY OF THE STATE PARKS IN THE FLORIDA KEYS
by
Ed Lane

The chain of sun-drenched islands of the Florida Keys and associated
coral reefs are unique in the continental United States. There are five state
parks in the Keys, each with its own special features that will enhance
a visit to this subtropical realm. The state parks are: John Pennekamp
Coral Reef, Lignumvitae Key, Indian Key, Long Key, and Bahia Honda
(Figure 1). The geological history of the Florida Keys is an interesting story
that will add to one's enjoyment of these parks.
The Florida Keys lie along an arc from Miami to Key West, a distance
of about 135 miles. The islands have been divided into Upper and Lower
Keys, based on their orientations and on the differences between the two
types of limestone that compose them. The Upper Keys, composed of the
Key Largo Limestone, extend from Biscayne Bay southwest to Big Pine
Key. The Lower Keys, made of the Miami Limestone, encompass Big Pine
Key to Key West (Figure 1). Figure 1 also shows the distinctive orienta-
tions which characterize the Upper and Lower Keys. The Upper Keys are
oriented in a linear northeast-southwest direction, while the Lower Keys
are oriented perpendicular to them, in a northwest-southeast direction.
The reasons for their orientations are discussed below.

GEOLOGICAL HISTORY

The Florida peninsula is the emergent portion of a wide, relatively flat
geologic feature called the Floridan Plateau, which forms a rampart be-
tween the deep waters of the Gulf of Mexico and the Atlantic Ocean (Figure
2). The Florida peninsula is located on the eastern side of the plateau.
The edge of the plateau lies over 100 miles west of Tampa, while on the
east it lies only three or four miles off the coast from Miami to Palm Beach.
Near the southern rim of the plateau's escarpment lies a fringeline of
living and dead coral reefs. The dead coral reefs form the islands of the
Florida Keys. The edge of the Floridan Plateau, marked by the 300-feet
depth contour line, lies four to eight miles south of the Keys. Today, living
coral reefs grow in the shallow waters seaward of the Keys. This environ-






BUREAU OF GEOLOGY


Figure 1. The Florida Keys, showing locations of the State parks, and the
extent of the Key Largo Limestone and the Miami Limestone geological
formations.







LEAFLET 14


ment is ideal for the growth of coral: a shallow-water shelf, subtropical
latitude, and the warm Gulf Stream nearby.
The geological history of the Florida Keys began about three million
years ago, when a shallow sea covered what is now south Florida. During
the next 2.8 million years, often called the Pleistocene Ice Ages, world
sea levels underwent many fluctuations of several hundred feet, both
above and below present sea level, in response to the waxing and wan-
ing of the great glaciers. Colonies of coral became established in the
shallow sea along the rim of the broad, flat Floridan Plateau. The sub-
tropical climate allowed the corals to proliferate, forming reefs. As sea
levels fluctuated the corals maintained footholds along the edge of the
plateau: their reefs grew upward when sea levels rose, and their colonies
retreated to lower depths along the plateau's rim when sea levels fell. Dur-
ing times of rising sea levels, dead reefs provided good substrates for new
coral growth. In this manner, during successive phases of growth, the Key
Largo Limestone accumulated up to 200-feet thick in places. The Key
Largo Limestone is a white to tan limestone that is primarily the skeletal
remains of corals, with invertebrate shells, marine plant and algal debris,
and lime-sand. The Key Largo Limestone varies irregularly in thickness
from about 75 feet to over 200 feet. In the Lower Keys the Key Largo
Limestone is covered by the Miami Limestone. The last major drop in sea
level exposed the ancient reefs, which are the present Keys.
During reef growth, carbonate sand banks periodically accumulated
behind the reef in environments similar to the Bahamas today. One such
lime-sand bank covered the southwestern end of the coral reefs and, when
sea level last dropped, the exposed lime-sand or ooid bank formed the
Lower Keys. This white to light tan granular rock, the Miami Limestone,
is composed of tiny ooliths, lime-sand and shells. Ooliths may be up to
2.0 mm in diameter and are made of concentric layers of calcium carbonate
deposited around a nucleus of sand, shell, or other foreign matter.
Throughout the Lower Keys the Miami Limestone lies on top of the coral-
line Key Largo Limestone, and varies from a few feet up to 35 feet in
thickness. The northwest-southeast aligned channels between islands of
the Lower Keys were cut in the broad, soft, oolite bank by tidal currents.
Then, as today, the currents flowed rapidly into and out of the shallow
bay behind the reefs, keeping the channels scoured clean.
Exposures of the Key Largo Limestone and Miami Limestone can be
seen in many places along the Keys: in canal cuts, at shorelines, and in
construction spoil piles.







BUREAU OF GEOLOGY


x -300 Depth in feet below sea level.


--_ Edge of Floridan Plateau


NMt to sai.L


\
\
\
9'


S-100 x
f -..-* -200 x


-10,800 x


GULF of


Figure 2. Oblique view of the Floridan Plateau, showing the islands of the
Florida Keys fringing its southern rim.


x -300






LEAFLET 14


ENVIRONMENT

The climate of the Florida Keys is subtropical to tropical, with rare, brief,
below-freezing temperatures. The plants, animals, and ecosystems are
a blend of temperate and tropical species.
Because the Keys receive some of the lowest amounts of rainfall in
Florida, because they are surrounded by salt water, and because the rocks
of the Keys are permeable, obtaining adequate supplies of fresh water
has always been a problem. There are no reliable natural sources of
potable groundwater, although some small, unpredictable and fluctuating
lenses of fresh-to-brackish water occur at shallow depths. Fresh water must
be obtained by the pioneers' technique of capturing rain runoff in cisterns,
by importation via the pipeline along US 1, or by desalinization.
Elevations over most of the Keys are less than 10 feet above mean sea
level, although Key Largo and Key West have small areas that rise slight-
ly over 15 feet. The islands slope very gradually up from the sea to flat-
tened, gently rounded tops. Relief is slight on the bedrock surfaces, seldom
exceeding one or two feet. Irregularities of the rock surfaces are a result
of the heterogeneous topography of the coral reefs that created the islands,
and also the result of erosion and solution of the limestone rocks after
exposure above the sea. Solution features, such as pitted and pinnacled
surfaces, occur everywhere on the Keys. Sinkholes, up to several feet in
diameter and several feet deep, are abundant but many are filled with peat
or carbonate sediments, which masks them from casual detection. Vegeta-
tion preferentially takes root in them, providing clues to their location.
Compared to the rest of Florida, there is very little quartz sand on the
Keys. Most of the sand is of carbonate origin, not quartz sand. Carbonate
sand is derived from the erosion of limestone, from particles precipitated
in water, or as by-products in the life processes of some marine plants
and animals. A few islands, notably Long Key and Bahia Honda, have
beaches of loose carbonate sand that veneers the bedrock; most other
beaches are exposed, pitted and pinnacled limestone. Extensive commer-
cial development and construction has resulted in large quantities of crush-
ed limestone "fill" covering many areas of the Keys.
The subtropical Florida Keys present somewhat of a paradox with
respect to vegetation. In contrast to the usual picture of tropical, verdant
rainforests and luxuriant plant cover, large areas of the islands present






BUREAU OF GEOLOGY


bare, rocky surfaces or sparse grass cover. Several factors combine to
create a stressful environment for many types of plants. Top soil, in the
usual sense, is almost non-existent on the islands. The "soil" consists
of weathering byproducts of limestone or carbonate debris, which provides
few nutrients and limited rooting material. The mean annual rainfall for
the Keys is the lowest of any part of Florida, averaging as much as 50
percent less than the wettest areas of the State. Rainfall on the Keys
decreases from about 50 inches per year at Key Largo to as little as 25
inches per year at Key West. In addition, the rainfall is rapidly lost through
high evaporation or it readily percolates downward through the few feet
of porous rock to the underlying brackish water table. Any plant attemp-
ting to colonize the islands must also be salt-tolerant, since the atmosphere
is laden with salt spray. These conditions restrict the types of plants that
can grow on the islands, and they curtail the growth of the plants that do
gain footholds.
The foundations of the islands are ancient, dead coral reefs. However,
more recent changes in the Keys are the result of natural and biological
forces acting as geological agents, which are constantly at odds in ad-
ding to or eroding the islands. Perhaps the most important constructional
biological agents are mangrove trees, which are ubiquitous in the Keys.
Mangroves are salt-tolerant trees that thrive in the tidal zones along sub-
tropical and tropical coastlines (Figure 3). In south Florida and the Keys
mangroves are one of the most important components in the coastal marsh
ecosystems. Figures 3, 4 and 5 illustrate the effects of mangroves along
the islands' shorelines. A mangrove's thick tangle of aerial prop roots act
as a baffle that catches and holds sediments, from both landward and
seaward directions. Figure 4 shows a carbonate mud bank forming around
a stand of mangroves. The lime mud accumulating in shallow water (lighter
toned) is an ideal substrate for young mangrove seedlings, seen here in
progressively younger generations offshore, reaching to join the main
island to the small mangrove island in the right background. In this typical
fashion, mangroves stabilize shorelines and add new land to the Keys.
The labyrinthine mangrove islands and tidal channels shown in Figure 5
are the result of such mangrove growth and sediment accumulation. Con-
versely, mangrove roots also provide convenient supports for new colonies
of oysters, which may provide rock foundations for future generations of
mangroves.






LEAFLET 14


Some marine animals are intensively destructive to the limestone
islands, and a significant portion of modern erosion on the rock coasts
of the Keys has been attributed to the direct action of organisms that bore
and burrow into the rocks. Marine animals whose growth and feeding re-
quirements are destructive include certain sponges, worms, barnacles,
clams, echinoids, and chitons. Many of these animals can be seen by ex-
ploring along the rocky shorelines of the islands. The pinnacles and pits
of the limestone should be examined closely, however, because some of
the animals' camouflage blends with the rocks.
Hurricanes and tropical storms are agents of destruction, altering ex-
posed shorelines by erosion, salting the land by storm-surge flooding, and
damaging the coastal marshes that act as buffer zones between high land
and sea. While rains associated with them bring large amounts of fresh
water to the region, from man's viewpoint they tend to be more destruc-
tive than useful.




STATE PARKS

The Florida Keys are geologically and botanically unique in North
America. The vegetation of the Keys is of West Indian, or Caribbean, origin.
Extensive mangrove swamps fringe the Keys, while tropical hardwood
hammocks cover upland areas. A great variety of trees and shrubs are
found in the hammocks, including species with exotic sounding names,
such as gumbolimbo, Florida poisontree, mahogany, mastic, Jamaica
dogwood, pigeon plum, strangler fig, and lignumvitae (Figures 6 to 13).
During Florida's colonial period, many stands of these tropical trees were
felled to supply commercial and shipbuilding demands of various coun-
tries. In order to preserve and protect the remaining populations of plants
and animals, Florida's state park lands are managed to appear as they
did when the first Europeans arrived. Consumptive uses, including hun-
ting, livestock grazing and timber removal, are not permitted. Florida's
state parks fulfill an important purpose as representative examples of
"Original Natural Florida."























0
on




.....


IZ-





Figure 3. Mangrove trees, showing thickly tangled prop roots. Note the
many mangrove seedlings sprouting in the shallow water. Photo by Dr.
Renate Skinner.






















r-







Figure 4. Mangrove seedlings in the process of colonizing a shallow lime-
mud bank (the light-toned band across middle of picture). In time the small
mangrove island in the background will be joined to the main island, on
the left. Photo by the author.



Co

































Figure 5. Aerial view of part of John Pennekamp park. The labyrinth of
tidal channels through the mangroves serve an important function as a
nursery in the ecosystem of the Keys, providing food and shelter to many
marine animals. Another important function of such mangrove jungles that
fringe coastlines is to protect the shorelines from erosion. Photo by Dr.
Renate Skinner.


tl*1~1~7-(






LEAFLET 14


Figure 6. The gumbolimbo tree (West Indian Birch) (Bursera simaruba)
has smooth bark, is up to 60 feet high, with a trunk up to three feet in
diameter. The fruit is rounded, triangular, in clusters, with a thick, dark
red covering (from Fla. Div. of Forestry, 1980).


Figure 7. The Florida Poisontree (Hog Gum) (Metopium toxiferum) has thin,
reddish or orange-brown bark, often spotted from exuded dried gum which
has caustic properties. It grows up to 40 feet high and resembles the non-
poisonous gumbolimbo. WARNING: Precautions should be taken in iden-
tifying this tree, as it is as poisonous as poison ivy. All parts of this tree
act as a contact skin-poison to many people (from Fla. Div. of Forestry,
1980).






BUREAU OF GEOLOGY


Figure 8. The West Indies Mahogany (Meliaceae = Chinaberry Family)
grows to 50 feet high, up to two feet in diameter, with thick, reddish-brown,
scaly bark. Fruits are dark reddish-brown, ovate, up to five inches long
(from West and Arnold, 1946).


Figure 9. The Mastic tree (Jungleplum or Wild Olive) (Sideroxylon
betkissinum) grows up to 70 feet high with a trunk up to four feet in
diameter. Fruits are olive-shaped, with firm yellow skin (from Fla. Div. of
Forestry, 1980).






LEAFLET 14


Figure 10. The Jamaica dogwood (Florida Fishfuddle tree) (Piscidia com-
munis) grows up to 50 feet high and up to three feet in diameter. The fruit
is a four-winged pod, three or four inches long. Natives of the Caribbean
made a poison from the bark of the roots, leaves, and young branches,
which stupified fish so they could be picked out of the water (from Fla.
Div. of Forestry, 1980).


















Figure 11. The Pigeon Plum (Pigeon Seagrape) (Coccolobis floridana)
grows to heights of 70 feet, with trunks up to two feet in diameter. The
fruit is a dark red to black berry about one-third inch long (from Fla. Div.
of Forestry, 1980).






BUREAU OF GEOLOGY


Figure 12. The Florida Strangler Fig (Golden Fig) (Ficus aurea) seedlings
develop on the upper branches and trunks of other trees. As the roots
grow down the host's trunk, a dense crown of foliage shades out the host's
crown. In time the fig is firmly rooted in the ground and the host is nearly
or totally dead. Aerial roots drop from branches to the ground, forming
additional trunks. It grows to 50 feet high, with trunks up to three feet in
diameter. Fruits are red, round to ovate, 3/4-inch long, and stalkless (from
Fa. Div. of Forestry, 1980).


Figure 13. The Lignumvitae tree ("Tree of Life") (Zygophyllaceae = Bean-
caper Family) grows up to 25 feet high, with trunks up to two feet in
diameter. Fruits are bright orange, ovate, five-angled, about 3/4-inch long
(from West and Arnold, 1946).







LEAFLET 14


VISITORS' INFORMATION

All plant and animal life is protected in state parks, as are non-living
materials, such as rock and mineral specimens or artifacts. Parks open
at 8 a.m. and close at sunset year-round. For visitors' safety, regulations
prohibiting the feeding of animals are enforced. Pets must be on a six-
foot, hand-held leash at all times. They are not permitted in campgrounds,
swimming areas, or any park buildings. Intoxicants are not permitted in
any area of state parks. Some activities and facilities are accessible to
the handicapped. Inquire at the respective park.
Snorkeling and diving are the best ways to observe the coral reefs and
associated marine life. The DIVERS DOWN flag must be displayed while
in the water. NEVER swim alone. Do not touch anything you are unsure
of and treat all underwater life with respect. Do not touch, grasp, or stand
on coral, for it will die. Anchors are very destructive when dropped into
coral; therefore, anchor only in sandy bottom areas. Spearfishing is pro-
hibited in state parks.

JOHN PENNEKAMP CORAL REEF STATE PARK

John Pennekamp Coral Reef State Park is the first underwater state
park in the United States. Pennekamp and the adjacent Key Largo Coral
Reef National Marine Sanctuary extend 8.5 nautical miles into the Atlan-
tic and are 21 nautical miles long (approximately 10 by 25 miles), cover-
ing about 178 square nautical miles. These areas were established to pro-
tect and preserve a portion of the only living coral reef in the continental
United States. The park is named for the late John Pennekamp, a Miami
newspaper editor who contributed to the establishment of the Everglades
National Park and to the perpetuation of Florida's park system.
Tropical vegetation, shore birds and marine life may be seen within the
park. The mangrove swamp, with a boardwalk through it, allows visitors
to explore the swamp's ecosystem. On the upland areas the tropical hard-
wood hammock's nature trail provides views of numerous exotic trees.
Boulders around the swimming areas are Key Largo Limestone, showing
examples of the coral reef lithology of this geological formation. The park's
living reef is a modern counterpart of the ancient reef that produced these
rocks. The present reef is made of the same plant and animal communities






BUREAU OF GEOLOGY


Figure 14. John Pennekamp Coral Reef State Park, showing points of in-
terest on the reef tract: 1) Molasses Reef is toured by the Park's glass-
bottomed boat; 2) White Banks Dry Rocks, with 5 to 15 feet of water, is
a good reef to snorkel; 3) French Reef has underwater caves, cliffs, and
canyons; 4) the Benwood Wreck, the hull of a World War II freighter that
was torpedoed by a German sub; 5) Garret's Reef and the Cannon Patch,
less than 10 feet under water, has several coral encrusted cannon; 6) Gre-
cian Rocks, an easy reef to snorkel, averaging about six-feet deep; 7) Key
Largo Dry Rocks has a nine-feet tall bronze statue, "Christ of the Deep,"
in water less than 20-fe.et deep; 8) The Elbow has several ship wrecks
and shallow water for diving; 9) Carysfort Reef, with depths from five to
40 feet, and Carysfort Reef Light Station, built in 1882, provides some
of the best diving conditions in the Keys. Map compiled from NOAA
Nautical Chart 11451, U.S. Geological Survey topographic maps, and park
information guides.


























Boat Rental

-I






S /Pennekomp


Coral Reef.
S tt Pork,,. "


Ocean O 00' 200,

Scale


Figure 15. John Pennekamp Coral Reef State Park






BUREAU OF GEOLOGY


that created the emergent islands of the Keys.
Although the park and marine sanctuary encompass hardwood ham-
mocks, mangrove swamps, seagrass beds, and coral reefs, the coral for-
mations and associated marine life attracts the most visitors. Coral reefs
are among the most beautiful and interesting of all living communities.
They represent a colorful, very complex and prolific ecosystem. Daily,
glassbottom boat tours are available for visitors who do not wish to dive
onto the reef. Figure 14 shows the locations of points of special interest
on the reef tract.
The park offers a variety of recreational facilities, including a visitor
center with nautical history exhibits and slide programs, concessions, a
dive shop, sailboat and canoe rentals, boat launching ramp, picnic and
camping areas, and swimming areas with bathhouses (Figure 15).
Park Rangers provide special snorkeling programs to familiarize visitors
with the most desirable method of observing the coral reefs. Maps and
instructions are available for the most interesting sites on the reef. Camp-
fire programs are provided during the winter season. Guided walks and
canoe trips are provided year-round. For further information, write or phone
John Pennekamp Coral Reef State Park, P. O. Box 487, Key Largo, FL
33037. Telephone (305) 451-1202.

LIGNUMVITAE KEY STATE BOTANICAL SITE

The serenity and isolation of remote islands have always captured man's
imagination. Lignumvitae Key is no exception. To step ashore here is to
take a step back into the past (see Figure 16).
The Matheson House, built in 1919, has changed little over the years.
A windmill provides power, and fresh water is supplied from a cistern which
is filled by rain falling on the roof. This is how island people lived during
pioneer times when most of their needs were met by the land and sea
around them.
This island is an ancient counterpart of a modern patch reef. Patch reefs
are smaller reef complexes that grow in relative isolation, often behind
the main reef line. The patch reef that became Lignumvitae Key grew
behind its main reef, now the Florida Keys. Numerous modern patch reefs
can be seen in the shallow water between the Keys and the main reef
line that fringes the Florida Straits.








LEAFLET 14


State Preserve
(closed)


Upper Matecumbe Key


House


LIGNUMVITAE KEY


Public Boat Launch


Lower Matecumbe Key


N
A
0 1000

Feet


Site


Figure 16. Lignumvitae Key State Botanical Site, showing the location
of Indian Key State Historical Site southeast of Lower Matecumbe Key.


-4
0






BUREAU OF GEOLOGY


Thousands of years ago, the island began as a living coral reef jutting
up from the sea floor. As great quantities of water began to freeze into
glaciers at the earth's poles, the sea level dropped, exposing the top of
the reef and forming an island composed of fossilized coral rock.
As time passed, storm tides and waves left seaweed, driftwood, and
other organic debris stranded on the bare rock. This material began decay-
ing and forming small pockets of soil in depressions in the coral rocks.
Then a few seeds arrived from other tropical islands some floating on
the sea or carried by the winds, while others came in the digestive tracts
of migrating birds. The seeds sprouted and began to grow, drop leaves,
produce flowers and seeds, mature, die, and decay. With the passing of
each generation, a complex and diverse tropical hammock colonized the
remains of this ancient coral reef.
The virgin tropical forest that thrives here is typical of the kind of scenery
that was once enjoyed on most of Florida's Upper Keys. As the Keys were
developed to accommodate an increasing number of people, most of the
unique vegetation was scraped away making the tropical forest of
Lignumvitae Key a very rare and special place. Here, a visitor can walk
in the shade of trees with strange names like strangler fig, poisonwood,
lignumvitae, and gumbolimbo.
Access to the Key is limited to privately owned boats or charter boats
available at nearby marinas. A two-hour guided tour of the island and the
Matheson House is given at 9 AM and a one-hour tour at 1 PM and 3 PM
from Wednesday through Sunday. The visitor should wear walking shoes
and bring mosquito repellent. To protect the fragile vegetation and en-
vironment of the Key, visitors must stay within the clearing except in the
company of the interpretive guide or ranger. For further information, write
or phone Lignumvitae Key State Botanical Site, c/o Long Key State Recrea-
tion Area, P. O. Box 776, Long Key, FL 33001. Telephone: (305) 664-4815.

INDIAN KEY STATE HISTORICAL SITE

Indian Key is located about three-quarters of a mile to the southeast
of the north end of Lower Matecumbe Key (Figures 16, 17 and 18). Even
though it is in front of the main reef tract the geological history of Indian
Key is similar to Lignumvitae Key, discussed above. A small patch reef,
exposed by falling sea level, formed the limestone foundation for Indian
Key.







LEAFLET 14


This small coral island, little more than 10 acres in area, figures prom-
inently in Florida's early history, from pre-historic Indians to the 1830's.
Archeological excavations have shown that Calusa Indians lived in the
Keys for several thousand years prior to the arrival of the first Spanish
explorers, who discovered Florida in 1513. The eastward-flowing Gulf
Stream provided a quick route home for the treasure-laden Spanish fleets.
The shoals and reefs south of the Keys proved to be extremely dangerous
when tropical storms or hurricanes blew up unexpectedly. Many treasure-
fleets were sunk on the reefs along the Keys, to the profit of the Indians.
Later, in the mid-1700s, salvaging shipwrecks, or "wrecking," as it was
called, became so profitable for local fishermen that the practice attracted
pirates. American occupation of Florida in 1821 put an end to pirating.
Key West became the wealthy center of the salvage-wrecking industry.
A newcomer, Jacob Housman, challenged the monopoly of Key West
in 1831, when he bought Indian Key and built his own wrecking colony
there. A few years of prosperity followed, during which Housman's political
activities established the new Dade County, with Indian Key as the coun-
ty seat. His fortunes declined rapidly, forcing him to mortgage the island.
In 1840, during the Second Seminole War, a large band of Indians attacked
the community, killing several people and destroying buildings. No one
has lived on Indian Key since the late-1800s. The archeological excava-
tions, the foundations of buildings, cisterns, and partially restored buildings
provide the visitor with a sense of the colorful, adventurous lives of these
"wreckers."
An observation tower, boat dock, shelter, and trails are provided. There
are no rest rooms. Most facilities and activities are not accessible to the
handicapped. For further information, write or phone the Park Manager,
Long Key State Recreation Area, P. O. Box 776, Long Key, FL 33001.
Telephone: (305) 664-4815.
LONG KEY STATE RECREATION AREA

The bedrock of Long Key is Key Largo Limestone, although much of
it is thinly covered by carbonate sand, Figures 19 and 20. The park beach
in Figure 19 shows the vulnerability of the key's shoreline to wave ero-
sion; the shoreline has been cut back to a point where trees are being
undermined. Comparing this exposed, eroding beach with the shoreline
in Figure 4, which is accreting seaward due to mangrove growth, illustrates
the importance of mangroves as a geological agent and as a buffer against
storm damage.



























0',~ '~i
* t1 t
A! ~ 1
44.
*"'v4"A4At


*1sZii'' "^"^|tli-., ,,s *-";**
.;'i '- a r ;1^ **1 Knc 1 "


Figure 17. Indian Key State Historical Site, a Pleistocene age patch reef, now exposed above sea
level. The darker tones in the water locate deeper channels that are scoured by strong tidal cur-
rents between the islands of the Keys. Photo by Dr. Renate Skinner.







LEAFLET 14 23


DOCK


Figure 18. Map of Indian Key showing archeological sites.


I,~L~1~ Ilb ~







BUREAU OF GEOLOGY


The shallow flats seaward of Long Key and the mangrove-lined lagoons
support an abundance of marine life. Wading-bird populations can be
readily observed in these areas, particularly during the winter months. A
trail winds through natural areas of the key, along the beach, and over
a mangrove-lined lagoon.
Long Key State Recreation Area provides an opportunity to enjoy the
natural values of a typical Florida Key. The subtropical climate, clear waters
and abundance of marine life associated with the Florida Keys have at-
tracted man since early times. The Calusa Indians lived off the abundant
plant and animal life long before the first Spanish explorers arrived. After
the Spanish occupation, the keys attracted settlers from other islands, such
as the Bahamas, who made their living from the sea.
These remote keys were no longer isolated when, in 1912, the Key West
Extension of the Florida East Coast Railroad was completed. The viaduct
west of Long Key was the first bridge built by the railroad crews, and was
the trademark of the Henry Flagler railroad.
Long Key was an important depot during the days of the railroad. Flagler
established the Long Key Fishing Club as a mecca for the world's greatest
saltwater fishermen. The era came to an end on September 2, 1935, when
a hurricane destroyed the fishing club and the railroad.
Park Rangers present campfire programs and lead guided walks year-
round. They also offer informative programs on snorkeling, fishing, canoe-
ing, and the marine ecology of the area. For further information, write or
phone Long Key State Recreation Area, P. O. Box 776, Long Key, FL
33001. Telephone: (305) 664-4815.

BAHIA HONDA STATE RECREATION AREA

In Spanish, Bahia Honda means "deep bay." This southernmost state
recreation area's boney skeleton is an ancient coral reef thinly covered
by beaches and dunes of carbonate sand, and mangroves (Figure 21).
Bedrock is Key Largo Limestone.
The very shallow, clear water around the island provides an opportuni-
ty to observe marine plants and animals that inhabit the carbonate-sand
sea bed. Bahia Honda has a number of tropical plants that are not often
found on the other islands. Among the rarer species are the satinwood
tree, spiny catesbaea and dwarf morning glory. The birdlife of Bahia Hon-
da includes beautiful and rare species such as the white-crowned pigeon,
great white heron, roseate spoonbill, reddish egret, osprey, brown pelican,
and least tern.






















In
m
?- I









Figure 19. Ocean-facing beach at Long Key showing erosion. The trees are rooted
in thin carbonate sand that covers bedrock. Photo by the author.








26 BUREAU OF GEOLOGY


FLORIDA BAY


Areas


Campfire


Tower


ATLANTIC OCEAN


Figure 20. Map of Long Key State Recreation Area.


SVICMTY MAPYd
G.~ ~ ~ I OCLI
t.0W W rb K


'000


N


















Entrance Station


Camping


0 400

Feet


Figure 21. Bahia Honda State Recreation Area.


West


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~.~LC:





BUREAU OF GEOLOGY


The island remained fairly isolated and remote until the railroad span-
ned the channels with bridges of steel and concrete to link Key West with
the mainland. The island became part of land holdings of the Florida East
Coast Railroad until the company abandoned the line after the 1935 hur-
ricane destroyed the railroad. The original train trestle is still visible as
part of the old Bahia Honda Bridge.
Regular campfire programs and guided walks are provided during the
winter season, with special interpretive programs provided to groups by
reservation. At the northeast end of Sandspur Beach, a nature trail follows
the shore of a tidal lagoon, goes through a coastal strand hammock and
returns along the beach. For further information, write or phone Bahia Hon-
da State Recreation Area, Route 1, Box 782, Big Pine Key, FL 33043.
Telephone: (305) 872-2353.




SELECTED BIBLIOGRAPHY

Florida State Park leaflets, available at the respective parks.
Florida Division of Forestry, 1980, Forest Trees of Florida: 102 pp.
Multer H. Gray, 1971, Field Guide to Some Carbonate Rock Environments,
Florida Keys and Western Bahamas: Miami Geological Society, Miami,
FL. 158 pp.
West. Erdman and Lillian E. Arnold, 1946, The Native Trees of Florida:
Univ. of Florida Press, 212 pp.









FLORIDA DEPARTMENT OF NATURAL RESOURCES

BUREAU OF GEOLOGY
FLORIDA GEOLOGICAL SURVEY

Walter Schmidt, Chief
Peter M. Dobbins, Admin. Asst. Alison Lewis, Librarian
Jessie Hawkins, Custodian Sandie Ray, Secretary

GEOLOGICAL INVESTIGATIONS SECTION


Thomas M. Scott, Senior
Albert Applegate, Geologist
Brian Caldiwell, Research Asst.
Ken Campbell, Geologist
Cindy Collier, Secretary
Don Harris, Research Asst.
Richard Howard, Laboratory Tech.
Richard Johnson, Geologist
Jim Jones, Draftsman


Geologist/Administrator
Ted Kiper, Draftsman
Susan Kruhm, Staff Asst.
Ed Lane, Geologist
Jacqueline M. Lloyd, Geologist
Teresa Meyer, Staff Asst.
John Morrill, Core Driller
Albert Phillips, Asst. Driller
Frank Rupert, Geologist


MINERAL RESOURCE INVESTIGATIONS
AND
ENVIRONMENTAL GEOLOGY SECTION

J. William Yon, Senior Geologist/Administrator
Paulette Bond, Geologist Connie Garrett, Research Asst.
Laura Cummins, Research Asst. Shelton Graves, Research Asst.
Diane Donnally, Research Asst. Ron Hoenstine, Geologist
Steve Spencer, Geologist

OIL AND GAS SECTION

SL. David Curry, Administrator
Clarence Babcock, Engineer Joan Gruber, Secretary
Brenda Brackin r Secret-ary David Pbe;Geologist
Robert Caughey,Geologisti Joan Ragland Geologist
Cynthia ok, Geologist: Gwendolyn Staten, Secretary
Charles Tootle, Engineer:










FLRD GEOLOSk ( IC SUfRiW


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