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THE GEOLOGY OF
FALLING WATERS
STATE RECREATION
AREA


FLORIDA DEPARTMENT OF NATURAL RESOURCES







STATE OF FLORIDA
DEPARTMENT OF NATURAL RESOURCES
Virginia B. Wetherell, Executive Director



DMISION OF RESOURCE MANAGEMENT
Jeremy Craft, Director



FLORIDA GEOLOGICAL SURVEY
Walter Schmidt, State Geologist and Chief


LEAFLET 16

THE GEOLOGY OF FALLING WATERS
STATE RECREATION AREA

by

Frank Rupert and Ed Lane


Prepared by the
FLORIDA GEOLOGICAL SURVEY
TALLAHASSEE
1992


Camr Faling Water Sink viewed from above the overlook (FGS photo).







THE GEOLOGY OF FALLING WATERS
STATE RECREATION AREA

by

Frank Rupert, P.G. No. 149 and Ed Lane


Falling Waters State Recreation Area aptly derives its
name from one of Florida's most interesting geological
features. The centerpiece of the park is the 100-feet deep,
20-feet diameter vertical Falling Water Sink, into which a
small stream cascades during the wet seasons. The water
falls into the sink and disappears underground into a maze
of subterranean caverns developed in the 30 million year
old limestone which underlies the region. Falling Water
Sink owes its existence to a unique and fascinating
geologic history.

GEOLOGIC HISTORY

The region surrounding Falling Waters State Recreation
Area is underlain by ancient marine limestone. Limestone
visible in the park today is comprised largely of the calcium
carbonate shells of sea creatures which lived in the shallow
seas covering northern Florida between 20 and 30 million
years ago. As the animals died, their shells settled to the
sea floor, slowly building a thick sequence of limestone.
Some of these limestone strata are exposed in the walls of
Falling Water Sink.
Over the succeeding millions of years, the sea
advanced and retreated many times. During low sea level,
when the ancient sea floor was exposed as dry land,
erosion and weathering removed portions of the deposited
sediments. During periods when sea levels were higher,
more sediments, such as limestone, sands and clays, were
deposited on top of the older limestone. These, too, were
eroded during intervening periods of low sea level.
Therefore, only a partial, sporadic record of the last 30







million years of geologic time is represented in the wall of
Falling Water Sink.
With the onset of the Pleistocene Epoch ice age about
two million years ago, huge glaciers formed across much
of northern North America. Although the glaciers never
reached Florida, sea water was locked up as glacial ice,
and worldwide sea level dropped. The Falling Waters area
once more became stranded inland, high above sea level.
The newly exposed land was attacked by the forces of
weathering and erosion. Streams removed and reworked
sediments lying at the surface. The underlying limestone
was also subjected to dissolving or dissolution by rain
water, made slightly acidic by absorption of atmospheric
carbon dioxide and organic acids in the soil. This water
preferentially circulated along natural fractures, joints, and
more permeable beds within the limestone. For millions of
years, this percolating water slowly dissolved a network of
caves, caverns, and vertical solution pipes through the
originally solid rock. In some caverns, enough rock was
dissolved so that the overlying sediments were no longer
supported. When this happened, the overburden collapsed
into the cavern, forming a sinkhole. Such an event created
Falling Water Sink. Sinkholes and other collapse
depressions are very common on the terrain around Falling
Water Hill. Such a depression-pocked landscape formed
on limestone is called karst terrain.
Falling Water Hill, which attains a maximum elevation of
about 320 feet above mean sealevel, is believed to be a
remnant of a once more extensive highland area which
spanned much of northern Florida. Over the millennia,
extensive karst dissolution, coupled with erosion by surface
streams, has lowered the land surface that surrounds the
hill for miles in all directions. Today, Falling Water Hill
stands as an erosional outlier, separated by lower terrain
from hills of similar elevation to the west and south.
Falling Waters sink is situated on the south side of
Falling Water Hill. The stream cascading into the sink is
fed along its course by numerous small springs flowing out
of the hill.







GEOLOGY


Much of our knowledge about the deeper rocks
underlying Falling Waters Hill was derived from geologic
samples recovered from one of Florida's first oil wells,
drilled during the period 1919 to 1921 near Falling Water
Sink. The well is situated just off the nature trail about 400
feet northwest of the sink overlook. It was drilled to a total
depth of 4,912 feet below land surface. Although no oil
was discovered, the rock cuttings brought up during drilling
revealed a wealth of information about the deeper geologic
formations. The deepest rocks encountered are marine
sediments originally deposited in a vast sea which covered
much of the southeastern United States during the
Cretaceous Era, about 150 million years ago. Most of the
overlying rocks are younger marine limestones, attesting to
this area's long inundation by the sea. The near-surface
rocks, including those exposed in the park today, represent


Derrick on the site of the Chipley Oil Company well, 400 feet northwest of
Falling Water Sink, March 20, 1920. The well was a dry hole (FGS archives).
































0 MILE 0.5
0 KM 0.8


Topographic map of Falling Water Hill showing park boundary and the
geologic croa msecton location.

the last 30 million years of earth history.
The base of Falling Water Hill is comprised of
Oligocene Epoch Suwannee Umestone, which was
deposited in a warm, shallow sea. This geological unit
selves as an important freshwater aquifer throughout the
local area. Microscopic fossils in the rock enable
geologists to determine that the Suwannee Limestone was
deposited approximately 30 million years ago. About 70
feet of Suwannee Limestone is exposed in the lower portion
of Failing Water Sink.








MOE
-350
A FALLING WATER HILL A
300
WmLE
250
OIL WELL
FALLING
200 .-- -- WATER
7 -SINK







Northwest-southeast geologic cross i i i section through Falling Water Hill.


thinner and much younger limestone called the
Chattahoochee Formation. This formation formed in a
shallow sea during the Miocene Epoch, about 20 million
years ago. The Chattahoochee Formation contains typical
marine fossil shells such as pectens and oysters.
Approximately 30 feet of Chattahoochee Formation. is
exposed in the sides of Falling Water Sink, above the
Suwannee Limestone.
In much of Falling Water Hill north of the sink, a series
of younger, Middle and Upper Miocene marine and deltaic
sediments, called the Alum Bluff Group, overlie the
Chattahoochee Formation. Locally, the Alum Bluff Group
is comprised of unfossiliferous, green, clayey siltstone,
attaining a thickness of about 50 feet under the highest part
of the hill. Because of their elevationally higher position,
these sediments do not occur in the walls of Falling Water
Sink.
Capping Falling Water Hill and forming the uppermost
sediments in the sink are a series of undifferentiated sands
and clayey sands. These deposits represent river delta and
marine sediments laid down during the last 5 million years.










Near the sink, the undifferentiated sands overlie the

Chattahoochee Formation. North of the sink, they overlie

the Alum Bluff Group, and extend to the top of Falling

Water Hill, a total thickness of about 60 feet.




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Geologic section in Falling Water Sink showing rocks deposited during the
OBgocene, Miocene, and Pliocene-Recent Epochs.


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LIMESTONE


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SINKS


The most impressive sinks in the park, including Falling
Water Sink, formed when the roof of an underground cavern
or solution pipe collapsed. This caused the overburden
sediments to slump into the cavity, opening a funnel, or a
tube-shaped hole at the surface, and exposing the limestone
bedrock in the walls of the sink. As the land surrounding
Falling Water Hill was lowered by dissolution and erosion, the
water table was also lowered sharply. The deep, tubular
shape of Falling Water Sink may have been due, in part, to
rapid downward dissolution in pace with the lowering of the
ground water surface.
Many of the sinks in the area also take the form of cover-
subsidence sinkholes. In this type, a bowl-shaped depression
in the earth occurs, which does not open into a hole.
The age of formation of the sinks is uncertain, but it has
probably been a continual process for many thousands of
years. Geologists believe that the ground-water table was
considerably lower during the Pleistocene sealevel lowstands
than it is today This may have left many of the formerly
water-filled subterranean caverns high-and-dry, which, in turn,
could have caused overburden collapse and sinkhole
formation.

CAVES

Today, some of the caverns developed in the limestones
under Falling Waters State Recreation Area are above the
ground-water table, and contain dry, air-filled passages.
Spelunkers, or cave explorers, have mapped two stretches of
cave in the park. These are shown on the accompanying
map. One is the cave which drains Falling Water sink. This
cave extends westward nearly 80 feet from the opening in the
base of the sink. Water flows along the floor of the cave and
disappears under an impassable limestone wall.
A second, larger cave system runs under the walkway
below the Falling Water sink overlook. It zig-zags some 400
feet southeast of the entrance sink, with connections to
various small surface sinks. As you walk along the sink loop
trail, you may observe cave entrances in some of the sinks.
Please remember that the caves are off-limits to all but
experienced spelunkers who have obtained permission from
the Florida Park Service.
































A typical oave passage within Failing Water
Cave (photo courtesy Florida State Cave Club).


An 80 feet-high cylindrical dome in Falling
Water Cave, deep under the Park (photo
courtesy Florida State Cave Club).









WATER FLOW
UNDIR WALL
S WATERFALL
DOME I STEEP WTERRAL
OV.M go, IG Or..N... CAVE SYSTEM
APPROX. I. DEEP
DODOM .... IT""
S NDI WALL SILI CONNECTION nT.EN FALLING WATERS
N WLL THISE 1S NOT KNOWN

\ STATE RECREATION AREA
0 (MALL SINK IS' DeP

\ Ilnr Iln*
4' HIGH

Sl ( ow TO PICNIC AREA
MPE OH \ DEPRESSION OR EHARP
FLORIDA STATE CAV CLUE C ANOE IN ILIVATION
NOVIMIIR fES, JAUARY FA MAY IPM
M. EVANSI UNMAPPED PAIAOII
CLOVER E NTRANC" N APPROXIMATt LOCATION
K. IKEMRRIOAN OMI A10 H OF WALKWAY ON IURFAC
0 OAA \ 0 5 FilT
r MITR S (ALL FIT I I I I
o, LNI \ ENTRANCE

S --IMALL ROOM WITH ROCK N


N 1 LOOP PAssAOK


LOOP PAODAOE
Dy BoMe PIT WITH LOO$ %I J
04' W N 10 H
DOME I' UPPIR LIVIL ITH SKYLIGHT % 6 DROP
UNIXPLORID IT WITH TURTLES 4- uPY D Ul
SMALL INTRANCI 12' DOP
FROM SINK '(\ s / \ oe %
ROCK e WATER FLO

OCK S' DO -or % .OP
UP 4. %s Is W 11 L*ARG ROCN

10, DROP .
IOP 1 I




































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WATERSArea

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Oer''ookiZ FALLING WATERS
Sink dff STATE RECREATION AREA
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FLRD GEOLOSk ( IC SUfRiW


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