The rocks in which the caves of the Florida Caverns State Park were
formed are limestone. This rock is made of the mineral calcite, calcium
carbonate, and it is soluble in pure water under conditions of favorable
structure, a continuous supply of moving water and time. However, in the
water of Florida this limestone is readily dissolved, because the humid
climate and prolific vegetation contribute organic and mineral acids to
water and make it a highly potent solvent that is capable of dissolving
large amounts of this rock.
Limestone is as a rule jointed vertically and bedded horizontally.
Openings along these joints and beds provide easy avenues of travel for
water. The ultimate source of all of Florida’s ground water is from the
rain and precipitates from the air. As this rain water falls through the
air it becomes charged with carbon dioxide gas which combines with water
to form carbonic acid. On the ground humic acids from rotting vegetation
is added. These are the common natural solvents of limestone. A good
portion of this acid charged water soaks into the ground, and as it
descends through lime rock small portions of the rock are dissolved.
However, relatively little solution occurs until sufficient water enters
the rock to fill completely all the available pores. In this portion of
the rock, saturated with water and bathed with weak acids, solution is
most active. Because of the pressure of water entering the rock, ground
water tends to move horizontally along bedding planes which offer the
easiest exit. Thus, cave systems generally are developed horizontally and
one system may lie over another and they may be connected by vertical
tubes and rooms.
[Illustration: Weird vistas and eerie silhouettes meet the eyes of
visitors who explore the amazing networks of trails in Florida Caverns.
Droplets of mineral water, dripping through the ages, formed these
underground caves into a natural, but highly artistic wonderland.]
Any rain water entering the rock from the surface makes its way downward
to fill completely all the pores of the rock at some depth. At it moves
downward and then into the saturated rock through pores and open spaces
it acts as a slow solvent to increase the size of the openings and to
connect them to form a continuous system of channels through which
streams filling the cavities may run.
As large caverns are formed, solution cavities of irregular shape are
gradually cut out and enlarged. Some of these may be expanded to a point
near the surface where surface deposits (largely sand in Florida) will
collapse into the cavern and a sink is formed. The larger part of
Florida’s natural lakes, sinks, depressions and ponds are the result of
solution of the underlying limestone. These features range from small
pits a few feet in diameter to large depressions several miles broad.
Many are perfectly round, others are highly irregular. Some are
cone-shaped with rocky bottoms, some have broadly developed flat bottoms
and are known as prairies. Still others are vertical tubes, only a few
inches in diameter in some cases, that extend as much as one hundred feet
down into the limestones. These are “natural wells.”
_Florida’s State Parks include miles of white sand beaches, fine streams,
beautiful springs, excellent fishing waters, floral displays, wooded
ravines and outstanding recreational areas. It is the Florida in which
the Indians hunted, fished and lived in original surroundings of great
natural charm and wildlife profusion ... where yet remains the memory and
imprint of Spanish conquistadores, French crusaders and Anglo-Saxon
colonizers. Phenomena such as disappearing rivers, vanishing lakes,
historic shrines, virgin country, strange subterranean landscapes are all
to be seen inside the parks._
[Illustration: “Fresh crisp bacon” formed by water flowing originally
from a crack or elongate hole and cascading down the face of the
limestone. The deposit formed as a small ridge that then acted as the
course of subsequent water which added additional deposits. The dark
bands contain some impurity to give a color to the ordinarily white
calcite.]