Karst Map of the Conterminous United States - 2020

Map shows karst areas of the continental United States having sinkholes in soluble rocks (carbonates and evaporites), as well as insoluble volcanic rocks that contain sinkholes. The volcanic bedrock areas contain lava tubes that are voids left behind by the subsurface flow of lava, rather than from the dissolution of the bedrock.  Hot spots of sinkhole activity are also shown in areas of greater susceptibility. Source: Progress toward a preliminary karst depression density map for the conterminous United States https://doi.org/10.5038/9781733375313.1003