South Dakota
Long before South Dakota’s Mount Rushmore was carved into the now-familiar visages of four U.S. presidents, the mountain of granite was known as the Six Grandfathers by the Lakota Sioux, for whom it was a site of important spiritual quests. Now Mount Rushmore National Memorial is a popular stop on cross-country road trips, attracting more than 2 million visitors a year.
Mount Rushmore was partially inspired by the Confederate Memorial Carving on Stone Mountain in Georgia, another large-scale sculpture carved into the side of a granite mountain. Granite, an igneous rock that erupts underground, cools slowly, allowing for the large crystals to form that give the rock its hard texture. The granite intrusion (batholith) that is Mount Rushmore formed around 1.6 billion years ago and was exposed at the surface between 70 and 40 million years ago, when the Laramide orogeny uplifted the Rocky Mountains.
To create the sculpture, more than 450,000 tons of rock were blasted and hacked out of a granite batholith that was forced above ground between 70 and 40 million years ago.
Mount Rushmore, née Six Grandfathers, is only one of many granite formations in the Black Hills of South Dakota. An alternate site, the Needles in Custer State Park, was originally selected for the carving, but the sculptor, Gutzon Borglum (who also worked on Stone Mountain), thought the granite, which had eroded into spires, was too soft for large-scale carving. Instead, the current site was selected based on its smooth, fine-grained granite that erodes at a rate of an inch every 10,000 years—plus the fact that it faces southeast and is bathed in sunlight most of the day.
Between October 1927 and October 1941, Borglum, his son, Lincoln, and 400 workers blasted and sculpted the sixty-foot-high carvings of George Washington, Thomas Jefferson, Theodore Roosevelt, and Abraham Lincoln into the rock. The workers used dynamite to blast big chunks out of the rock before drilling many side-by-side holes. These neighboring holes honeycombed the rock enough to allow small pieces to be removed with hand tools.
If Jefferson appears to be oddly placed, peering over Washington’s left shoulder, it’s because he was intended to appear on Washington’s right, but the rock there turned out to be too soft. The incomplete figure was dynamited out and wedged between Washington and Roosevelt. Originally, the presidents were to be depicted down to their waists, but the project went far over budgets of time and money, and after Borglum died in 1941, the landmark was completed with just the leaders’ faces.
A mere seventeen miles west of Mount Rushmore stands the Crazy Horse Memorial, another massive granite sculpture. Started in 1948 on the side of Thunderhead Mountain, the Crazy Horse Memorial currently depicts the Native American warrior’s face and a partially chiseled outstretched arm. The carving has been mired in controversy and underfunding for decades, but if completed, it will be one of the largest sculptures in the world, topping 560 feet high.
You might fly over Mount Rushmore en route to Rapid City, South Dakota.
