[Source: Shannon Livick, Cortez Journal] -- Something looked different at the popular Square Tower House at Mesa Verde National Park when research archaeologist Julie Bell took visitors by the most photographed site at the park recently. Mesa Verde National Park research archaeologist Julie Bell takes notes on the damage done by a 4.5-ton slab of rock that fell from the cliff face at Square Tower House sometime during the holidays. Bell stands in front of the slab, which is setting on top of the wall of Kiva B. There was rubble where rubble should not be. A 4.5-ton slab fell on the picturesque ruin sometime last month, smashing a storage room, rupturing the wall of a kiva and coming to rest inside a two-story room at the far end of the site. “It pierced the kiva like a knife,” Bell said. “Fortunately, it didn’t get the tower.”
The site at the park is well known because it is easy to photograph in the afternoons and visitors take a short walk to an overlook where the 1,200-year-old ruins can be viewed. The site has the tallest tower in the park, measuring 26-feet high. The four-story tower sets among 80 rooms and seven kivas. The ruin has been closed to visitors since the 1950s, so Bell and a small group recently grabbed a ladder to assess the damage close-up. “It’s amazing it didn’t do more damage,” Bell said. The rock took out a 4-foot section of a wall at the site and completely destroyed another wall that was part of an alcove. Bell said there were original beams in one of the walls. The rock also pierced the walls of one of the kivas at the site and left rubble strewn about. Fortunately, the shock waves set off when the rock hit likely didn’t damage the tower, Bell said.
Slabs shearing off the sandstone cliffs isn’t a new problem at Mesa Verde. Preston Fisher, a structural engineer at the park, spends a good amount of time monitoring the sandstone that houses the park’s famous cliff dwellings. He places devices called crack monitors in the cracks to gauge when a slab might start to shift, but the one the size of a Volkswagen bug that fell recently wasn’t one that Fisher was worried about. “We look at alcoves from the bottom every year,” Fisher said. “We try to knock off what we can before sites are open to the public.” Fisher called what happened at Square Tower House “alcove exfoliation” and said it has been happening for centuries. Park employees are also on the lookout for small flakes from the cliffs as signs of a possible fall.
[Note: To read the full article, click here. Photo courtesy of Mesa Verde National Park.]