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
Charles E. Rushmore of the four presidents' heads on the mountain - the largest single contribution. The Memorial was dedicated by President Coolidge on August 10, 1927. Rushmore was also a member of the Phi Gamma Delta Fraternity. Mr. Rushmore was also a member of Kane Lodge No. 454, F&AM (NYC). Charles E. Rushmore Charles Edward Rushmore (December 2, 1857 – October 31, 1931) was an American businessman and attorney for whom Mount Rushmore is named. Born in New York City, he was the son of Edward Carman Rushmore and Mary Eliza (née Dunn) Rushmore, of Tuxedo Park, NY. He was married to