These data were subsetted by Texas Parks and Wildlife Department in 2015 to derive the Texas portion of a 2014 USGS karst dataset for the whole USA. The USGS summary of this data follows: This report describes new digital maps delineating areas of the United States, including Puerto Rico and the U.S. Virgin Islands, having karst or the potential for development of karst and pseudokarst. These maps show areas underlain by soluble rocks and also by volcanic rocks, sedimentary deposits, and permafrost that have potential for karst or pseudokarst development. All 50 States contain rocks with potential for karst development, and about 18 percent of their area is underlain by soluble rocks having karst or the potential for development of karst features. The areas of soluble rocks shown are based primarily on selection from State geologic maps of rock units containing significant amounts of carbonate or evaporite minerals. Areas underlain by soluble rocks are further classified by general climate setting, degree of induration, and degree of exposure. Areas having potential for volcanic pseudokarst are those underlain chiefly by basaltic-flow rocks no older than Miocene in age. Areas with potential for pseudokarst features in sedimentary rocks are in relatively unconsolidated rocks from which pseudokarst features, such as piping caves, have been reported. Areas having potential for development of thermokarst features, mapped exclusively in Alaska, contain permafrost in relatively thick surficial deposits containing ground ice. This report includes a GIS database with links from the map unit polygons to online geologic unit descriptions.
Copyright statement: Texas portion of the original 2014 USGS karst data set for the whole USA was extracted by Texas Parks and Wildlife Department. Original data for this map were compiled and edited by David J. Weary and Daniel H. Doctor of the U.S. Geological Survey (USGS). Most of the spatial data compiled in this project originated as lithologic map units on geologic maps produced by various State geological surveys. Versions of the original source maps are available for purchase or download from the respective State geological surveys. Much of the digital map data for this project was compiled from a series of integrated geologic map databases for the United States produced by the USGS Mineral Resources Program (see http://mrdata.usgs.gov/geology/state/, accessed May 16, 2014). Use of the USGS digital geologic data provided a consistent data structure within which a derivative database of areas with potential for karst could be constructed. In some areas, other miscellaneous datasets and publications were referenced to facilitate accurate map compilation. These references are cited in the COMMENTS field of the feature data.