Landscapes
National karst map
Karst is a type of topography that is formed over limestone, gypsum, and other rocks by dissolution. It is characterized by sinkholes, caves, and underground drainages. Human activities, such as urbanization, agricultural practices, water exploitation, and deforestation, can negatively impact karst areas, resulting in subsidence and ground-water contamination.
Sinkhole collapses can cause major disruption to structures and infrastructure.
Karst landscapes are of interest to biologists because they provide unique habitats for aquatic and terrestrial organisms living on the surface or underground. The quality of water in a karst aquifer affects the health of ecosystems as well as in adjacent rivers and streams fed by karst waters. Karstic carbonate rocks contribute to specific substrate and chemical requirements for some aquatic species and may be a determining factor in their spatial distribution. Inventories of cave dwelling vertebrates and invertebrates collected by various natural resource agencies are becoming increasingly important as indicators of ground-water quality in karst aquifers.
Karst terrain covers nearly 25 percent of the United States, and some are on Federal lands. The USFWS, Bureau of Land Management, USDA Forest Service, EPA, and National Park Service are among the agencies that have expressed interest in learning more about how karst terrain impacts their land management and regulatory responsibilities.
Map of the conterminous U.S. showing Federal lands and areas of karst terrain.
In response to the increasing need for accurate and detailed information about the distribution and types of karst terrains in the United States, the USGS worked with a diverse group of karst experts to develop a long-term plan for karst mapping on a national scale. The plan calls for the USGS to produce a national, web-based karst map. The national map will consider various karst-related factors, such as the distribution of carbonate and evaporite units, intrastratal karst, karst beneath surficial overburden, and percentage of area covered by karst. The map will be derived primarily from maps prepared by the individual states. The website will have links to state- and local-scale maps and related data. The newly formed National Cave and Karst Research Institute (NCKRI) will establish the web-based network of karst information that will be used to build the national map. The website will be designed to educate the public and legislators about karst issues, to provide a basis for cave and karst research, and to aid Federal, State, and local land-use managers in managing karst resources.
