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The Black Hills is an isolated mountain range rising from the Great Plains of North America in western South Dakota and extending into Wyoming, United States. [3] Black Elk Peak, which rises to 7,242 feet (2,207 m), is the range's highest summit. [4]
The Black Hills of South Dakota is one of the few remaining exposed portions of the Trans-Hudson orogenic belt. The peaks of the Black Hills are 3,000–4,000 feet (910–1,220 m) above the surrounding plains, while Black Elk Peak – the highest point in South Dakota – has an altitude of 7,242 feet (2,207 m) above sea level. [ 4 ]
The Laramide orogeny occurred in a series of pulses, with quiescent phases intervening. The major feature that was created by this orogeny was deep-seated, thick-skinned deformation, with evidence of this orogeny found from Canada to northern Mexico, with the easternmost extent of the mountain-building represented by the Black Hills of South ...
Uplift and erosion followed, as the layered complex is unconformably overlain by the extensive lava flows of the Carlton Rhyolite Group. [9] The rhyolites are a brown-red to orange porphyritic rock with 5–10 mm orange-colored alkali feldspar crystals. Most of the rounded hills on Fort Sill are made of this rhyolite, including Medicine Bluffs ...
The Bighorn Mountains (Crow: Basawaxaawúua, lit. 'our mountains' or Iisaxpúatahchee Isawaxaawúua, 'bighorn sheep's mountains' [1]) are a mountain range in northern Wyoming and southern Montana in the United States, forming a northwest-trending spur from the Rocky Mountains extending approximately 200 mi (320 km) northward on the Great Plains.
After a series of devastating wildfires in 1893, U.S. President Grover Cleveland created the Black Hills Forest Reserve on February 22, 1897. [5] U.S. President William McKinley issued a presidential proclamation on September 19, 1898, appending the Black Hills Forest Reserve geographic boundaries while acknowledging the forest preservation decrees established by the Timber Culture Act and ...
BHOD was renamed "Black Hills Army Depot" (BHAD) in 1962. [1] Over the years, BHOD was used for storage and testing of chemical weapons, including sarin [4] and mustard gas. [5] Additionally, during World War II, the site also held Italian prisoners of war. [3] The Depot was closed on June 30, 1967, and the Igloo community was abandoned. [1]
The Black Hills Institute of Geological Research, Inc. (BHI) is a private corporation specializing in the excavation and preparation of fossils, as well as the sale of both original fossil material and museum-quality replicas.