Abstract - Geology of Jewel Cave National Monument, Custer County, South Dakota, with Special Reference to Cavern Formation in the Black Hills
Deal, Dwight. 1962. Geology of Jewel Cave National Monument, Custer County, South Dakota, with Special Reference to Cavern Formation in the Black Hills. M.S. thesis, University of Wyoming.
Geologic mapping of 14 square miles in the vicinity of Jewel Cave National Monument on the southwest flank of the Black Hills disclosed an east-west trending zone of normal faults whose north side is higher by at least 600 feet. Joint orientations rotate counterclockwise through at least 15 degrees from east to west across the area. The upper 360 feet of the Pahasapa limestone and the lower 160 feet of the Minnelusa formation are the only units exposed.
Black Hills caves formed under phreatic conditions in which groundwater flow was relatively independent of the development of solution channels. A complex of subaqueous and subaerial deposits developed during alternating phreatic and vadose conditions.
The sequence of cave events includes: solution of the caves leaving brown calcite veins protruding from walls to form boxwork cores, subaqueous deposition of brown calcite and sediment preceding a subaerial environment, subaqueous deposition of dogtooth spar preceding another subaerial environment, partial solution of all previously deposited carbonates and deposition of clay fill, silica cementation of fill preceding the removal of uncemented fill and the deposition of clay on cave walls, and the draining of the caves preceding the final period of subaerial deposition.
Black Hills caves have an unusually complex speleogenesis and may have started to form in the Oligocene.
Did You Know?
Fire is an important factor in protecting the prairie. Historically, fires burned across the prairie every 4 to 7 years. Fires burn the small trees that would otherwise march across the prairie and turn the grasslands to forest.