Sinkholes are cavities in the ground that form when water erodes an underlying rock layer. Sinkholes have both natural and human causes. The formation of sinkholes involves natural processes of erosion or gradual removal of slightly soluble bedrock (such as limestone rocks, carbonate rocks) by percolating water, the collapse of a cave roof, or a lowering of the water table. Sinkholes often form through the process of suffosion.
Manmade sinkholes are created when city development compromises the structural integrity of underlying rock. Roads, buildings, and other types of construction may cause water to collect in certain areas and wash away the supporting rock layer (especially at low sea levels and after a heavy rainfall).