You’ve heard the term “old as the hills”? Well, the Black Hills are pretty old. Some of the rock is estimated to be more than 2 billion years old. The granite spires west of Keystone (including Mount Rushmore) are relatively young, a mere 1.8 billion years.
"The geology of the Black Hills is complex,” according to Wikipedia. An understatement.
More than 90 percent of the sculpting work was done not with chisels or jackhammers, but with sticks of dynamite. The blasts removed about 450,000 tons of rock from the mountain between 1927 and 1941.
The dynamite blasted away rock and roughed out the figures to within three to six inches of the final carving surface.
There’s an old political joke -- we first heard it during the Carter administration, but it’s been applied to every president since.
Q. Why won’t they add President ______ to Mount Rushmore?
A. There’s not enough rock for two more faces.
But there is a bit of truth to that. In fact, when sculptor Gutzon Borglum began his carving in 1927, he intended to put Jefferson to the left of Washington. In fact, crews spent time roughing in the third president’s visage to Washington’s left. But the rock surface proved unstable, and Borglum ended up blasting it off and starting again to Washington’s right.
Occasionally folks will ask how long the four faces of Mount Rushmore will still be visible. After all, even the sturdiest materials eventually succumb to wind and water.
Geologists estimate that the Mount Rushmore loses about an inch of rock every 10,000 years, so Mount Rushmore will likely be around for some time.
You would think that an international icon like Mount Rushmore would have been named for an individual whose contributions to the development of the West merited such an honor. Pikes Peak is named for explorer Zebulon Pike. Terry Peak is named for the Civil War hero Gen. Alfred Terry.
That’s not the case for Mount Rushmore. It was named for Charles E. Rushmore, a New York attorney who was sent to Dakota Territory in 1884 to do some legal work. One day he and Bill Challis were headed to back to camp, and Rushmore asked if that rock outcropping over there had a name.