Mount Rushmore is getting its annual facelift.
Crews on ropes are working to repair time- and weather-related cracks in the national memorial in western South Dakota. The preservation work is done each fall on the granite faces of Presidents George Washington, Thomas Jefferson, Abraham Lincoln and Theodore Roosevelt.
"They use a silicone-based caulking material to seal cracks," Maureen McGee Ballinger, director of interpretation and education at Mount Rushmore, told the Rapid City Journal (http://bit.ly/ocmiu5). "They have a few larger cracks covered with Kevlar material and then sealed with the silicone caulk."
Kevlar is a material better known for its use in body armor.
The repair crew is made up of about 10 Mount Rushmore staff members trained in repair duties performed in potentially hazardous conditions.
"It's similar to rock climbing, but highly technical," Mount Rushmore superintendent Cheryl Schreier said.
The work includes close inspection of the rock for signs of developing problems. Crew members watch for rocks that might become dangerous and clean vegetation out of cracks.
"If vegetation is allowed to stay there, it can add to the expansion of those joints," Schreier said.
The work will stretch through next week. All facilities at Mount Rushmore will remain open, though portions of the Presidential Trail will be closed periodically as equipment is moved.