The word karst is a Germanized form of the name of a carbonate plateau that is situated above the Adriatic Sea immediately to the east of Trieste, Italy. The term has been generalized as a label for any similar region. The distribution of karst landscapes over the Earth’s surface to a large extent follows the distribution of carbonate (limestone and dolomite) and gypsum rocks, and together these make up about 15% of the Earth’s land area. Karst regions are characterized by a unique set of landforms including closed depressions, deranged drainage, sculptured bedrock surface, and residual hills. Karst regions also differ from other geomorphic regions by the presence of cave systems in the subsurface. In general, surface karst features are more pronounced in regions where the caves have direct hydrologic connections to the land immediately overlying the caves and the surface and subsurface features develop more or less simultaneously.