What is a Sinkhole?
For most Floridians, sinkhole is a frightening word. Visions of homes being swallowed, interstates caving in and lakes being sucked dry often flood a property owners mind. While occurrences like this are rare, sinkholes more commonly manifest themselves as something simple, like a crack in a wall or a door that won't shut properly.
Although they can be seen as a destructive force, sinkholes play an important role in Florida's unique aquifer system by increasing ground-water flow. Our freshwater supply in the future is dependant upon adequate appreciation and conservation of sinkholes.
Types of Sinkholes
The color-coded map to the right shows various types of sinkholes and the areas that those sinkholes are often found in Florida.
Region of exposed or thinly-covered carbonate rocks. Broad, shallow solution sinkholes dominate, with less common collapse sinkholes in areas with thicker overburden sediments.
Region of incohesive, permeable sand ranging from 20 to 200 feet thick. Small cover subsidence sinkholes dominate, with less-common collapse sinkholes forming in areas with clayey overburden sediments.
Region of cohesive, low-permeability clayey sediments 30 to 200 feet thick. Abruptly-forming collapse sinkholes dominate. The size of these sinkholes depends upon the thickness and bearing properties of the overburden sediments.
Region of deeply-buried carbonate rocks. Overburden sediments are primarily cohesive clayey sands and interbedded carbonates in excess of 200 feet thick. Sinkholes are uncommon, but rare deep collapse types and small subsidence sinkholes formed in shallow shell beds or carbonate lenses are possible.
Displayed below is a series of cross-sections illustrating what the various types of look like, and how they affect the geography around them.