LAB Pro University
Florida has more sinkholes that any other area in the USA. We call it karst topography or landforms. They include cypress domes, wet prairies, dry sinkholes and sinkhole lakes.
In Florida, the underlying basis for sinkholes is the presence of a porous limestone layer under the topsoil. Karst is land with springs, sinkholes, and streams that sink into ground. Sumter, Lake & Marion Counties have evaporite rocks, (salt, gypsum, and anhydrite) with a moderate risk of sinkholes. Evaporite rocks are under about 35 to 40 percent of the United States, though in many areas they are buried at great depths.
What causes a sinkhole? When the ground below the surface is carbonated rock, limestone, or other types of rock that dissolve over time, water circulating through the ground can cause the rock to dissolve away. A space or void can then develop under the ground. Sinkholes are created when surface materials dissolve the earth and there is insufficient material to fully support the earth. The surface will then collapse. A karst sinkhole may develop slowly into a circular shaped hole in the ground, or it could just collapse. The size and shape of the hole, and the speed that in which it forms will depend greatly on the size of the underground void and the amount of material on the bedrock. When the weigh of to surface material gets to heavy the surface can fail in a dramatic fashion. Some times the collapse occurs under a house or a road.
Humans can cause a sinkhole to occur. Some factors to look out for are ground water pumping (this lowers the water table), vibrations from blasting or heavy traffic or heavy loads on the surface.
Some indications of sinkholes are listed below:
1. There are depressions or an opening in the ground.
2. Cracks are present in the interior floors, walls and/or ceilings.
3. The windows and doors do not open and close properly.
4. There is a slope in the floor.
5. Stair steps have cracks on the outside walls.
6. Cracking or buckling of the concrete slab floors.
7. The well water has dirt or debris in it.
8. The house feels like it is shifting under your feel.
9. The house next door is a sinkhole house.