Water Resources and Geology of Mount Rushmore National Memorial, South Dakota: Geological Survey Water-Supply Paper, 1865
Powell JE, Norton JJ, Adolphson DG. 1973. Water Resources and Geology of Mount Rushmore National Memorial, South Dakota: Geological Survey Water-Supply Paper, 1865. United States Government Printing Office. Washington, DC
Ground water suitable for public supply can be obtained from fractured metamorphic and igneous rocks at Mount Rushmore National Memorial, SD. The memorial comprises three main drainage basins: Starling basin, Lafferty Gulch basin, and Easy Boundary basin. The total water supply was obtained from springs until 1967 when increasing numbers of visitors required development of additional sources. Mica schist is the most abundant rock in the memorial. The more prominent hills and mountains, however, are in large, northerly striking granite sills, some of which are several hundred feet thick. Pegmatite sills and dikes are also numerous. Several locations in the memorial have potential as future sources of ground-water supplies.