Charles E. Rushmore big game. One day, while accompanied by Ted Brockett of Keystone, South Dakota, Rushmore asked the name of the mountain and was told that it was Slaughterhouse Rock. Rushmore joked that his annual treks to the Hills had earned him the right to have the mountain named after himself. "So just for the hell of it," Urbanek claimed, the locals started calling the hill Mount Rushmore. Whatever the precise story, the United States Board of Geographic Names officially recognized the name "Mount Rushmore" in June 1930. Forty years after the initial 1885 naming, Rushmore donated $5000 towards Gutzon Borglum's sculpture
Mount Rushmore selected Mount Rushmore as the site for several reasons. The rock of the mountain is composed of smooth, fine-grained granite. The durable granite erodes only every 10,000 years, thus was more than sturdy enough to support the sculpture and its long-term exposure. The mountain's height of above sea level made it suitable, and because it faces the southeast, the workers also had the advantage of sunlight for most of the day. The Mount Rushmore area is underlain by well drained alfisol soils of very gravelly loam (Mocmount) to silt loam (Buska) texture, brown to dark grayish brown. Mount Rushmore has