Here we behold most wondrous sights
No mortal understands,
Of stalactites and stalagmites,
A house not made with hands.
Here Nature set to work her hands
In ages long since gone,
That man might quit his work on lands
To see and ponder on.
What means these fluted columns tall,—
These pendants from the dome?
These sculptured figures large and small,
Excelling Greece and Rome?
This drapery striped with Nature’s hues,
In regular spaces wrought?
These scenes man’s pride at once subdues—
They are beyond his thought.
The brute would look and turn away
To seek his fill of food;
’Tis ours to seek while here we stay,
The Great Creative Good.
The Architect within whose mind
The wonders of the sea,
The land, the sky, and all their kind,
Has wrought for you and me.
That we may look upon His deeds
And make our own expand,
For we alone best serve all needs
As tools within His hand.
—_Charles Cottingham_
_Marianna, Florida_
[Illustration: The stalagmite on the right is almost joined with a
stalactite. If it does, it will make a column. The grape-like clusters in
the upper foreground result when the flow of water is so slow that all of
it evaporates from the ceilings and deposits its mineral load there.]
FLORIDA CAVERNS
A NATURE-MADE WONDERLAND
_By_ Robert O. Vernon
_Assistant Director, Florida Geological Survey_
Florida is truly a child of the sea, since all the rocks composing its
land were formed directly on the ocean bottoms or by streams emptying
along the shores. From the record of these rocks we know that Florida has
been alternately above and below the sea many times in the geologic past.
In fact, the rocks visible in the park area at Florida Caverns, near
Marianna, Florida, and in the caves were formed from the hard shells of
animals that lived in one of these seas. As the animals died, their
shells accumulated on the sea bottoms, where they were covered by other
shells and hardened into lime rock.
These shells, called “fossils” by the geologist, are remains representing
cemeteries of the past. Along most of our coastal areas and sea bottoms
these shells are accumulating and forming limestone today. Such limestone
has formed also in the areas many miles removed from the present seas, as
in Iowa and other middle western states, telling us where seas have been
in the past.
[Illustration: As visitors explore the well-lighted trails and
passageways, they notice the icicle-like formations that hang from the
ceilings and the heavier ones that project from the floor. They study the
columns that seem to help support the rock above and the small passages
that extend in many directions. They notice sea shells imbedded in walls
and ceilings.]
How do we know that these limestones were formed in the sea? The next
time you go through the caves at Florida Caverns look closely at the
walls and you will be able to find the shells of _Scollops_ and other
clams. These animals lived only in shallow seas. The most common shell
that you will notice will be many small coiled flat shells about the size
of barley seed and flat thin disks about the size of dimes and quarters.
The animals that formed these shells are known as _Foraminifera_ and have
the fancy names of _Operculinoides_ and _Lepidocyclina_. They are one
celled animals (our most primitive) and are related to some of the
parasites that cause disease. These particular animals are extinct and
are known only from these rocks. From their association with other shells
they are known to have lived in shallow salt-water seas, and by means of
them the geologist is able to recognize this particular limestone, even
when it has been taken from a well drilled many feet below the ground
surface, for these small shells are recognizable even when the limestone
has been broken into fine fragments.
The limestone in which the caves of Florida Caverns were carved is known
from geologic studies made throughout the state to have been raised from
the sea by land movements after being formed and to have been extensively
eroded, following which it was again submerged under the sea and other
limestones deposited over the eroded surface. These limestones were
subsequently raised out of the sea to be eroded. Over this second eroded
surface a delta deposit of sand, clay and gravel was formed by streams
that emptied into the Gulf of Mexico.
The limestone that you will see in the caves is known as the Ocala
limestone, named from deposits near Ocala, Florida. In the region about
the Florida Caverns, limestones named the Suwannee limestone and the
Marianna limestone overlie the Ocala limestone. These limestones were
named for deposits recognized along the Suwannee river and at Marianna,
Florida. The sand, clay and gravel overlying all of these limestones are
not named but are believed to be the same age as deposits of the geologic
period popularly known as the “ice age.”
[Illustration: The “duck” results from irregular resistance of the
limestone to solution by ground water. These nodular masses were more
resistant and the less-resistant, usually softer limestone has been
removed from about them, leaving the form resembling a duck. Several
stalagmites are in the background. These are younger than the “duck.”]
Since emerging from the sea for the last time, this part of Florida about
the state park area has been undergoing changes constantly. The rocks
have been continuously attacked by elements of the weather, and
disintegrated where exposed. Running streams carry away much of these
products of weathering, but the work of water under the ground is the
major factor in the creation of these caves and the deposits in them.
This underground water, running through the pores in the limestone, has
been and is now wearing away portions of the land. These water channels
are isolated along fractures, bedding planes and other structural
weaknesses, or along poorly consolidated rock. The water dissolves the
limestone and carries it out into surface streams and on to the sea, and
as this material is carried away the rock, through which the water flowed
to the surface, is being worn away an equal amount. The amount of this
material being carried away is illustrated at Silver Springs, one of our
larger springs, where each day about 450 tons of rock is carried away
dissolved in water. When it is realized that this is only one of
thousands of springs in Florida, you can readily see what a large amount
of rock is being dissolved from beneath the ground and just how cavernous
the rock must be.
_All forms of wildlife are protected in Florida’s State Parks. Hunting,
trapping, or shooting are not permitted. These State Parks belong to you.
Help protect them._
_For further information on specific parks and historic memorials write:
Director, Florida Board of Parks and Historic Memorials, Tallahassee,
Florida._
[Illustration: Ground water cascading down a gentle limestone face was
ponded irregularly and the evaporation of the water along the outer edges
formed small terraces.]