Karst in the United States: A digital map compilation and database

Abstract

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.

Hydrogeology and hydrologic conditions of the Ozark Plateaus aquifer system

“…The Ozark system is an important aquifer in the Salem and Springfield Plateaus but is marginally productive in the St. Francois and Boston Mountains (MacDonald and others, 1977;Imes and Emmet, 1994). Carbonate units of the Ozark Plateaus have undergone extensive faulting, fracturing, and dissolution, resulting in the region being one of the major karst landscapes in the United States and karst units being the most important aquifers in the Ozarks (Weary and Doctor, 2014).…”

Measuring Inorganic Carbon Fluxes From Carbonate Mineral Weathering From Large River Basins: The Ohio River Basin

“…Surface geology to the north of the Ohio River is distinct from other parts of the basin, where Illinoian and Wisconsin glaciation has formed a buried landscape (Thornbury, 1940). Here, thick deposits of unconsolidated Quaternary materials include glacial till, loess, and lacustrine deposits that overlie carbonate bedrock, resulting in a sparse presence of exposed carbonates in the region (Thornbury, 1940;Ray, 1965;Weary and Doctor, 2014) (Figure 3.4). This is particularly evident among the Wabash, Great Miami and Scioto drainages.…”

“…(Ray, 1965;1974;Thompson et al, 2016). The glacial till overlying limestone units is of variable thickness, reaching 300 feet in some places (Veni et al, 2001;Weary and Doctor, 2014). These areas of carbonate bedrock beneath mapped surface deposits may supply alkalinity to rivers through baseflow.…”

“…These data were obtained using the U.S. karst map (Weary and Doctor, 2014) Moisture excess or deficiency was determined as the difference of precipitation and PET with negative values representing potential deficiency of water Mather, 1955, 1957;Sellinger, 1996).…”

“…The data used in this research were secondary, such that successful implementation virtually eliminates the need for raw data collection in calculating carbon sink for a particular basin. The study area was defined by the Hydrologic Unit Code (HUC) basin boundaries available through the USDA Natural Resources Conservation Service (NRCS) Geospatial Data Gateway, and the area of carbonate rock within each HUC basin is determined from the U.S. karst map (Weary and Doctor, 2014). These have been overlain and clipped to the basin extent using ArcGIS 10.2.2 software.…”