Mt. Rushmore, S.D. 2012
In early July of 2012, I had the opportunity to visit Mount Rushmore and the Crazy Horse Monument.
Mount Rushmore National Memorial is a large-scale mountain sculpture by artist Gutzon Borglum. The figures of America’s most prominent U.S. presidents–George Washington, Thomas Jefferson, Abraham Lincoln, and Theodore Roosevelt—represent 150 years of American history, (pictured below).
The Memorial is located near Keystone in the Black Hills of South Dakota, roughly 48 km from Rapid City.
The four “great faces” of the presidents tower 17,200 m above sea level and are scaled to men who would stand 1400 m tall.
Pictured above, The Sculptor’s Studio – a display of unique plaster models and tools related to the sculpting – was built in 1939 under the direction of Borglum. Originally, it was planned that the figures would be carved from head to waist, but insufficient funding forced the carving to end.
Borglum originally envisioned a grand Hall of Records where America’s greatest historical documents and artifacts could be protected and shown to tourists. He managed to start the project, but cut only 21 m into the rock before work stopped in 1939 to focus on the faces. In 1998, an effort to complete Borglum’s vision resulted in a repository being constructed inside the mouth of the cave housing 16 enamel panels that contained biographical and historical information about Mount Rushmore as well as the texts of the documents Borglum wanted to preserve there.
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. The Black Hills area was uplifted as an elongated geologic dome during the Laramide orogeny around 70 million years ago. Subsequent erosion stripped the granite of the overlying sediments and the softer adjacent schist leaving a granite mountain behind.
Later the same day, I visited the Crazy Horse Memorial. The Crazy Horse Memorial is a mountain monument under construction on privately held land, just a few kilometers west of Mount Rushmore. Pictured above, it will depict the Oglala Lakota warrior, Crazy Horse, riding a horse and pointing into the distance. The memorial was commissioned by Henry Standing Bear, a Lakota elder, to be sculpted by Korczak Ziolkowski.
The Crazy Horse Memorial is geologically very similar to Mount Rushmore: a pod of granitic migmatite surrounded by schists and slates. This and many other knobs in the Black Hills stand above their surroundings because they are more resistant than the metamorphic rocks around them.