Geologic Map of the Blackhawk Quadrangle, South Dakota

Rapid urbanization of the Black Hills Development Corridor parallels U.S. Interstate 90 along the eastern and northeastern flank of the Black Hills uplift. Development of one- to five-acre housing tracts in the Blackhawk Quadrangle is the most active in the state. A basic tool to assist in natural resource and geologic hazard evaluation of such areas is 1:24,000-scale geologic maps prepared by the South Dakota Geological Survey with assistance from the West Dakota Water Development District and the U.S. Geological Survey Educational Component of the National Cooperative Geologic Mapping Program (EDMAP).

Urban development is currently covering numerous deposits of sand and gravel, limestone, gypsum, and sandstone. The value of such commodities, and the effect of their long-term loss on the local economy, is rarely considered in the frantic rush to change rural land to urban and to increase the tax base for city and county governments. An additional, and potentially very significant, factor relates to protection of the recharge areas of local aquifers, for which there is presently little restriction. Geologic hazards include flood plains, sink holes, and landslides.

Courtesy of South Dakota Geological Survey, 2005.