The epikarst—the skin of the karst—is the thin zone near the karst surface. It includes the solutionally modified (karren) bedrock surface and the overlying and included regolith. Some authors include dolines as part of the epikarst. The epikarst frequently supports a perched aquifer and serves to retard and store infiltrating rainwater. It also serves as a habitat for a variety of organisms that live in the interstices. The epikarst must be considered in models of karst aquifers because it is a critical link between precipitation and in transport of water to the deep aquifer.