Climbers call snow cornices the fatal attraction of the mountains. They are beautiful but potentially deadly.
“They are incredibly dangerous,” said Peter Frenzen, a climber and public-affairs officer at Mount St. Helens National Volcanic Monument. “They are an unsupported overhanging shelf of snow. Their strength comes in how frozen and solid they are.”
The collapse of a cornice at Mount St. Helens led to the death this week of Joseph Bohlig, 52. The body of the veteran climber was recovered Tuesday.
The crater rim at the volcano is perfect cornice-forming terrain, Frenzen said. Winds from the south and southwest carry snow up and over the crater rim, forming shelves that cantilever out tens of feet over the 1,500-foot-deep crater.
Their own weight and warm weather can send them crashing onto the slope below, triggering an avalanche.
Skamania County Undersheriff David Cox said he couldn’t recall any other fatal falls into the crater since the 1980 eruption. In April 2008, a Portland, Ore.-area snowmobiler fell into the crater when a cornice collapsed. That man survived and was rescued.
“The real trick,” Franzen said, “is to be careful to know when you are on a cornice and when you are not.”
He said he once came upon a group of people lunching on a cornice they didn’t know was there. He also has heard stories of near misses where people crawled out on a cornice for a better look at the crater.
Cornices are hard to spot. The best advice, he said, is to stay back.
Franzen said a climbing ranger told him the best way to spot a cornice is to move sideways along the rim to see what you plan to walk on, “how overhanging it is.” If you can’t tell where the cornice begins and the rim stops, then don’t go, he advised.
The national monument Web site has a photo of cornices and includes the warning: “Do not approach the crater rim unless you can find a wind-scoured area where the surface of the rim is visible.”
Signs at the trailhead also warn of cornices. The warning is repeated on hiking permits needed to climb to the crater.
Between 12,000 and 15,000 people make the climb to the southwest crater rim each year, usually in the spring and summer. About 1,500 climbers make the longer winter climb.
The collapse of cornices serves a purpose, Franzen said. They are part of Mount St. Helens rebuilding itself.
The collapsing cornices and resulting avalanches are the major reason for the growth of Carter Glacier inside the crater, he said. Considered the youngest and fastest-growing glacier in North America, Crater Glacier is fed by falling ice and snow from the rim.