A sinkhole, also known as a sink, shake hole, swallow hole, swallet, doline or cenote, is a natural depression or hole in the earth's surface caused by karst processes - the chemical dissolution of carbonate rocks. Sinkholes may vary in size from less than 1 to 300 meters (3.3 to 980 ft) both in diameter and depth, and vary in form from soil-lined bowls to bedrock-edged chasms. They may be formed gradually or suddenly, and are found worldwide. These terms are often used interchangeably, though many distinguish between features a surface stream flows into and features with no such input. Only the former are described as sinks, swallow holes or swallets. A sinkhole on a glacier is called a moulin or a glacier mill.
Sinkholes can be human-induced and new sinkholes have been correlated to land-use practices, especially, from ground-water pumping, construction, and development practices. They can also form when natural water-drainage patterns are changed and new water-diversion systems are developed. Some sinkholes form when the land surface is changed, such as when industrial and runoff-storage ponds are created; the substantial weight of the new material can trigger an underground collapse of supporting material, thus, causing a sinkhole.(wiki)