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
Howard Rushmore Rushmore would dine with "his wife (Frances), Roy Cohn and his girl-friend." On November 27, 1949, Rushmore published in the "Journal-American" allegations of communist infiltration of US naval vessels. Though the facts of the article were invented by Rushmore, by coincidence the FBI was conducting its own investigation on the same matter. Initially, J. Edgar Hoover thought that Rushmore had access to genuine intelligence. Hoover then had Rushmore's telephone tapped. Later in Olympia, Washington, Rushmore testified before the Canwell Committee, a state committee to investigate subversive activities at the University of Washington. Rushmore switched the subject to Washington, D.C. He