- Created: Friday, 21 September 2012 20:29
FLORIDA SINKHOLES – CAUSES AND TYPES
The geological conditions that exist throughout large areas of our state make the occurrence of sinkholes not only common, but inevitable. As an illustration of just how often they occur, the Florida Geological Survey reports that in Hernando County alone there have been 232 new sinkholes confirmed in the first eight months of 2012.
The reason sinkholes occur is that the subsurface bedrock underlying much of Florida is made chiefly of carbonate, in the form of either limestone or dolomite. The shells we see along the seashore are also a carbonate mineral. And if you recall, many of the shells have been partially dissolved by the acid in the saltwater. The same thing happens to the carbonate bedrock when it is exposed to acidic water. Rain itself is slightly acidic and as it seeps through decaying plant debris and organic soils it becomes more so. When the acidic water comes into contact with the carbonate bedrock, small amounts of rock are dissolved and the water is neutralized. Small particles of rock are carried away by the water as it flows through the pores and crevices of the rock, further enlarging them. As time, (thousands of years), goes by, large cavities, valleys, flutes and caves are formed in the rock. The geological formation caused by this dissolution process is known as Karst topography. Karst is the German name for the region of Slovenia, extending into Italy, where the first scientific research on Karst topography was made in the late 1600’s.