FARMINGTON – Chaco Culture National Historical Park officials have grown concerned about the potential rockfall danger in the park, and have decided to close certain areas of the park.

Park officials don’t have any immediate concerns, but they decided to close select campground sites near what they called a “defined rockfall hazard zone.” The bulk of the closures are in Gallo’s Campground, where about 17 of the 49 sites are closed until further notice.

The campsite closures are based on a 2015 study by the Geologic Resources Division of the National Park Service. The study found the “arrangement of more resistant sandstone over more rapidly eroding mudstone,” which is common in the park, creates the potential for rockfall hazards. It went on to identify the park housing area and Gallo Campground, which are at the base of sandstone cliffs, as areas of “greatest concern because they are frequently occupied by people.” A rockfall-monitoring guidance and risk assessment of the areas was provided to the park.

The danger of rockfall is not new to the area but rather one that has threatened the area for centuries, according to a news release from the park. “The ancient Chacoans even made efforts to reduce the risk of potential rockfall damage at Pueblo Bonito,” the park said.

In 1941, the danger was realized when a rockfall occurred near some of the historical ruins in Pueblo Bonito, according to the park’s history. Threatening rock collapsed and destroyed more than 30 rooms in the Pueblo Bonito great house complex. According to the park, if those rooms were occupied at the time, “the inhabitants would have been crushed during this natural disaster.”

If visitors have reserved one of those closed spots, a park official said they can expect a refund within eight weeks or the option to reserve one of the remaining open sites.

lweber@durangoherald.com