Geology and Physiography of the Black Hills
A Tertiary mountain-building episode is responsible for the uplift and current topography of the Black Hills region. This uplift was marked by volcanic activity in the northern Black Hills. The southern Black Hills are characterized by Precambrian granite, pegmatite, and metasedimentary rocks that comprise the core of the entire Black Hills uplift. This core is rimmed by Paleozoic, Mesozoic, Cenozoic and sedimentary rocks (Wikipedia (more info) ).
South of the Pine Ridge is a fault which continues Northwest but subsides prior to the immersion of the Black Hills. The presence of the fault is apparent west of Pine Ridge where the southern side of the fault has upsurged (Gries, 1996 ).
The Black Hills are composed of Harney Peak Granite Batholith. The granite contains minerals such as quartz, feldspar, muscovite, and biotite. These minerals formed beneath the surface from molten magma. After the magma cooled and crystallized into solid rock, pegmatite dikes were formed when magma intruded into the granite (Geology Fieldnotes (more info) ).
Also found on the Black Hills are Jewel Cave and Mount Rushmore. Jewel Cave was formed by the dissolving action of acidic water. The cave hosts an array of speleothems and crystal formations (Geology of Jewel Cave (more info) ). Mount Rushmore is on the edge on the Harney Peak Granite Batholith (Geology Fieldnotes (more info) ).
Geology of Black HillsResources about the Geology of the Black Hills
- Black Hills Geology and Caves. This page is an introduction to the Geology and Caves of the Black Hills. ( This site may be offline. )
- Fossils and Minerals. This site is a collection of pages on the Black Hills' Geology. (more info)
- Geologic Provinces of the United States: Interior Plain Province. This USGS site provides an overview of the geologic history of the interior plains province. External links lead to information about national parks that exhibit interior plains geology and similar overviews of other physiographic provinces. An image gallery and additional maps and illustrations are also provided. (more info)
- Geology Field Camp Guide. This 14-page PDF from the National Park Service provides background information and a comprehensive road log for a two-day field trip in the White River Badlands of South Dakota. The information and activities are suitable for college students, and emphasizes surficial processes in the sediments of the late Cretaceous, Eocene, and Oligocene. ( This site is likely no longer available. )
- Geology of the Black Hills. This site is a virtual geology field trip of the Black Hills. (more info)
- The Geologic Story of the Great Plains. This site provides a non-technical description of the origin and evolution of the landscape of the Great Plains physiographic province. Information about the history and descriptions of the various landforms of the Great Plains is included. (more info)