YOSEMITE NATIONAL PARK, Calif. (AP) - Falling boulders are the single biggest force shaping Yosemite Valley, one of the most popular tourist destinations in the national park system. Now swaths of some popular haunts are closing for good after geologists confirmed unsuspecting tourists and employees are being lodged in harm's way.
On Thursday, the National Park Service announced that potential danger from the unstable 3,000-foot-tall Glacier Point, a granite promontory that for decades has provided a dramatic backdrop to park events, will leave some of the valley's most popular lodging areas permanently uninhabitable.
"There are no absolutely safe areas in Yosemite Valley," said Greg Stock, the park's first staff geologist and the primary author of a new study that assesses the potential risk to people from falling rocks in the steep-sided valley. The highest risk area is family friendly Curry Village, which was hit by a major rock fall several years ago.
A newly delineated "hazard zone" also outlines other areas, including the popular climbing wall El Capitan, where the danger posed by the rock falls is high but risk of injury is low because they aren't continuously occupied.
"Rock falls are common in Yosemite Valley, posing substantial hazard and risk to the approximately four million annual visitors to Yosemite National Park," reads the ominous opening line of the report.
The move to close parts of historic Curry Village, a camp of canvas and wooden cabins, comes four years after the equivalent of 570 dump trucks of boulders hit 17 cabins, flattened one and sent schoolchildren scrambling for their lives. The park fenced off 233 of the 600 cabins in the village.
The new report, obtained early by the Associated Press, now identifies 18 more that closed on Thursday.
Rock falls in and around the century-old Curry Village have killed two people and injured two dozen others since 1996. Since officials began keeping track in 1857, 15 people have died throughout the valley and 85 have been injured from falling rocks.
Yosemite Valley is ringed by 3,000-foot walls of granite. Since the last glacier retreated 15,000 years ago, the biggest factor shaping the most popular tourist destinations in the park has been the sloughing of rock when granite heats and cools and eventually breaks along fissures and cracks.
The report shows the greatest dangers are within 180 feet of the base of the cliffs. However, there is a 10 percent chance a potentially deadly boulder will fall outside of the zone every 50 years.
Park officials said two employee dormitories and parts of three others built in 2005 would be closing, which will further exacerbate a critical staff housing shortage.
Also on the closure list: a half-dozen sites at Camp 4, a $5-a-night camping bargain near El Capitan used mainly by climbers.
A representative of the park's concessionaire said visitors with reservations in Curry Village this summer will still get rooms, and some cabins can be moved to safer areas.