Courtesy of Mesa Verde National Park
It’s not often park officials at Mesa Verde have to call in high explosives, but this week was an exception.
A slide on the road leading into to the park left a 240-ton boulder teetering a mere 80 feet above the pavement.
“The concern was that since it was sitting on soils that were not consolidated with snow and ice mixed in, it would be hard to predict how it would move,” said Carol Sperling, Mesa Verde National Park chief of interpretation and visitor relations.
The original slide occurred Feb. 22, between 6:30 and 7:30 a.m.
“A large slab of rock broke loose from the cliff face above the park’s road, about three miles from the park entrance,” Sperling said. “Luckily no one was present to witness the fall of the boulders from the cliff face.”
The slide scattered boulders over a 150-foot area along the road, Mesa Verde spokeswoman Betty Lieurance said.
One 20-ton boulder landed on the road but was moved by Mesa Verde staff to clear the way for visitor traffic.
On Monday, Franklin Drilling and Blasting of Durango arrived with explosives to do a “controlled, single-load blast that shattered the rock into small, manageable pieces,” Lieurance said.
The blast removed the top 6 to 8 feet of the rock, about 100 tons of mass.
It took the contractor over two hours to drill the holes for the explosives. The stretch of road was closed for two hours while blasting occurred.
Though Mesa Verde’s famous cliff dwellings date back more than 500 years, the recent boulder cascade is a reminder the landscape there is far from static.
“We are glad that no one was in the area when the slide occurred,” said park Superintendent Cliff Spencer in a news release.