The above YouTube clip was embedded in this LiveScience article: "Sinkholes are an increasingly deadly risk in Florida, due primarily to the region's geology. The state is largely underlain by porous limestone, which can hold immense amounts of water in underground aquifers. As groundwater slowly flows through the limestone, it forms a landscape called karst, known for features like caves, springs and sinkholes.

The water in aquifers also exerts pressure on the limestone and helps to stabilize the overlying surface layer, usually clay, silt and sand in Florida. Sinkholes form when that layer of surface material caves in.

The collapse can be triggered by a heavy overload, often caused by a downpour or flooding, or when water gets pumped out of the ground."


Via Seth Dixon