Mount Rushmore community. Recent pine beetle infestations have threatened the forest. Mount Rushmore is largely composed of granite. The memorial is carved on the northwest margin of the Black Elk Peak granite batholith in the Black Hills of South Dakota, so the geologic formations of the heart of the Black Hills region are also evident at Mount Rushmore. The batholith magma intruded into the pre-existing mica schist rocks during the Proterozoic, 1.6 billion years ago. Coarse grained pegmatite dikes are associated with the granite intrusion of Black Elk Peak and are visibly lighter in color, thus explaining the light-colored streaks on the
Absaroka (proposed state) also a motivation for the proposed state, as Mount Rushmore (constructed 1927–1941) would be within Absaroka according to some plans. In a craze for state secession felt by the public, state automobile license plates bearing the name were distributed, as well as pictures of "Miss Absaroka 1939". The movement was unsuccessful and fairly short-lived. The chief record of its existence comes from the Federal Writers' Project, which included a story about the plan as an example of Western eccentricity. Absaroka (proposed state) Absaroka, (pronounced ab-SOR-o-ka) was an area in the United States, comprising parts of the states of Montana, South