Florida's underlying geology is revealed along the Suwannee River

FLORIDA'S DYNAMIC KARST TOPOGRAPHY is found in few places around the world. Over millions of years, a unique recipe of limestone, confining beds, organic matter, and moving water has sculpted Florida's seemingly flat terrain into a geologic piece of karstic artwork that includes complex networks of interconnected caverns and caves, drainage basins, disappearing rivers, flowing springs, collapsing sinkholes, circular lakes, and subsurface aquifers.

In addition to supplying a steady source of fresh drinking water, Florida's karst features provide stable habitats for native species, showcase a multitude of prehistoric fossils and artifacts, and offer unlimited opportunities for sports and recreation. Each year, the unique topography attracts attention from all over the world as millions of people travel to Florida for a chance to enjoy the state's vast collection of natural karst wonders.

GEOLOGIC HISTORY
Appreciation for the sculpted terrain of contemporary Florida begins with an understanding of the geologic processes that began over 40 million years ago when the region was at the bottom of the ocean. The Florida peninsula is actually the emerging portion of a tectonic platform called the Florida Plateau. Beneath the sea, the plateau acted as a marine shelf. As sea levels rose and fell, the remains of large and small sea creatures deposited on the shallow ocean floor creating a limestone bedrock. After sea levels dropped, a limestone peninsula, several thousand feet deep, emerged.

Florida's limestone bedrock is composed of calcium carbonate.

EROSION
Erosion is the basis of karst development. Florida's limestone bedrock is continuously dissolved by moving water on the surface and underground. Limestone is composed of calcium carbonate, which is only slightly soluble in pure water, yet easily dissolved by carbonic acid (H₂CO₃). Water collects carbon dioxide (CO₂) from the atmosphere as it precipitates from the sky. On the ground, surface water absorbs additional carbon dioxide from decomposing organic matter. The surface water becomes an acidic (pH 5) carbonic solution. The solution percolates down through the limestone bedrock through pores or cracks in the solid rock and moves through the aquifer as groundwater. Moving groundwater chemically dissolves joints and fractures in the limestone bedding plane creating subsurface cavities, caves, drainage basins, sinkholes and other geologic features that characterize Florida's karst topography.

POROSITY and PERMEABILITY of LIMESTONE
How groundwater moves throughout the bedrock depends on the porosity and permeability of the limestone. Limestone contains voids, or pores, and the volume of the pores is referred to as porosity. Porosity can be categorized as intergranular, between rock grains, or macrogranular, cavities and cracks that result from erosion.

The ease with which water moves through the limestone is called "permeability". For a rock to be permeable, its pores must be interconnected. Larger pores result in easier flow, or greater permeability.

porosity	permeability

Confining beds of siliclastic sediment deposits, such as clay, silt, and sand, obstruct pores and reduce the permeability of limestone. The beds create an impermeable layer that reduces or restricts the flow of water. A confining bed can line a sinkhole to create a pond or lake, assist in shaping the contours of a river's path, or restrict groundwater flow within a subsurface aquifer.

This	is at	Suwannee	Springs

PROTECTING KARST
As water dissolves limestone, Florida's terrain is continuously reinvented. Yet, topographical changes complicate the relationship between people and the environment. Florida persistently faces increases in urbanization and population growth that continue to alter and tax the natural environment. Failure to conserve and protect Florida's distinctive karst environment will create a bleak future for the many organisms that depend on it.

For more information about Florida geology, visit

The Florida Speleological Society

The Karst Waters Institute

The Florida DEP GeologicTopics web site.

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The Creators

This page was authored by Sarah Cervone.
Data is from the APIRS database.
This page was designed by Sara Reinhart.
Photography and graphics are by Ann Murray, Sara Reinhart and Vic Ramey.
Vic Ramey is the editor.

DEP review by Jeff Schardt and Judy Ludlow.

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This project is a collaboration of
the Center for Aquatic and Invasive Plants, University of Florida, and
the Bureau of Invasive Plant Management, Florida Department of Environmental Protection

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CAIP-WEBSITE@ufl.edu
Copyright 2003 University of Florida