Although fossils in the limestone tell us the age of the rock, they are not much help in determining the age of the cave. Most caves, including ours, are less than 10 million years old. Raccoon Mountain Caverns is at the edge of the Sequatchie Valley, which is one of the largest and most spectacular anticlinal valleys in the world. Limestone caves are formed when acids attack and dissolve the calcite in limestone. Most of the carbon dioxide comes from decaying leaves and vegetation in the soil.
Scientists believe that most caves form below the water table by slowly moving water.
After a rain, the rainwater mixes with the carbon dioxide in the soil and dissolves the limestone underneath. A cave is formed by water moving slowly in the small fractures below the water table. The rate of flow below the fractures changes as some limestone is easier dissolved than others due to variations in composition. As some channels grow larger they take in more water, thereby growing faster. The cave forming process may take thousands of years and can be stopped by either the lowering of the water table or the formation of air passages in the cave system due to surface erosion.