Mount Rushmore climbers to monitor and seal cracks annually. Due to budget constraints, the memorial is not regularly cleaned to remove lichens. However, on July 8, 2005, Alfred Kärcher GmbH, a German manufacturer of pressure washing and steam cleaning machines, conducted a free cleanup operation which lasted several weeks, using pressurized water at over . The flora and fauna of Mount Rushmore are similar to those of the rest of the Black Hills region of South Dakota. Birds including the turkey vulture, bald eagle, hawk, and meadowlark fly around Mount Rushmore, occasionally making nesting spots in the ledges of the mountain. Smaller
Mount Rushmore 31, 1941, Gutzon Borglum and 400 workers sculpted the colossal 60 foot (18 m) high carvings of U.S. presidents George Washington, Thomas Jefferson, Theodore Roosevelt, and Abraham Lincoln to represent the first 130 years of American history. These presidents were selected by Borglum because of their role in preserving the Republic and expanding its territory. The carving of Mount Rushmore involved the use of dynamite, followed by the process of "honeycombing", a process where workers drill holes close together, allowing small pieces to be removed by hand. In total, about of rock were blasted off the mountainside. The image of