Type of Sinkholes

There are three type of sinkholes.
First one is solution sinkholes.  Solution sinkholes form where soluble bedrock (i.e., limestone, dolomite, marble, and rock salt) is exposed at the land surface and thus subjected to weathering by dissolution.  Surface water collects in natural depressions and slowly dissolves a sinkhole.  Second one is subsidence sinkholes. Subsidence sinkholes are similar to solution sinkholes, except that the soluble bedrock is covered by a thin layer of soil and/or sediment. Surface water infiltration dissolves cavities where the bedrock is most intensely fractured, and the overlying sediment gradually moves downward into the expanding cavity.

Third one is collapse sinkhole. Collapse sinkholes form when surface materials suddenly sink into a subsurface cavity or cave.  The cavities form slowly over time, as groundwater moves along fractures in soluble bedrock and enlarges them through dissolution, and the actual collapse can occur in two different ways:                a.  When a cavity gets sufficiently large, the "roof" becomes too                   thin to support the weight of any overlying rock or sediment,                   so it collapses into the cavity.                 b.  Caves are sometimes able to support the weight of overlying                   sediments because they are filled groundwater.  However, if                   groundwater levels are lowered, then the overlying sediment                   will first erode and then collapse into the dewatered cavity.