Cool Things

 

Big Dismal Sink Maze

Entrenched in the sandhills of the Apalachicola National Forest, Big Dismal Sink drops some 75 feet before breaching the sparkling waters of the Floridan aquifer. The last 40 feet of the sink cut through sheer limestone walls mantled by a resplendent array of liverworts and ferns. This marvelous maze and nearby conduits lie in a region referred to as the Woodville Karst Plain, which stretches more than 450 square miles from Tallahassee's south side into the Gulf of Mexico. Limestone, ranging in age from 38 to 23 million years old, found here usually rests anywhere from the surface to just 20 feet below ground. The sugar-white sands overlying the limestone were deposited as terraces and dunes during higher sea level stands of the Pleistocene. Springs, sinkholes, lost rivers and karst windows (depressions in the land where roofs of underground streams have collapsed and exposed sections of caves) afford the only surface evidence of hidden caves and voids that riddle the karst plain's basement. Etched by the gradual corrosive effects of acidic water (primarily derived from rain passing through the atmosphere and forming carbonic acid) that dissolve more soluble portions of the bedrock, the caves themselves formed during the past two million years as Ice Age ocean levels fluctuated with climatic oscillations.