VIDEO: Mont Blanc’s Cosmic Ridge Collapses, Just Missing Climbers Below

When the Arête des Cosmiques near Mont Blanc collapsed this week in a spectacular avalanche of rocks, it’s a miracle that none of the trekkers below were hurt. The video, shot by one of a group of climbers, says it all.

“Aiguille de Midi; met Killian Jornet and watched the Cosmiques Arête fall apart,” Nick Lozika, one of the climbers, wrote on Instagram. Lower down the glacier, more climbers were coming up. For a time, it seemed as if they would be caught in the rockslide.

The area is one of the most visited in the mountains around Chamonix. It is popular as a first experience on alpine ridges. It is easily accessible from the Aiguille de Midi cable car and usually offers good-quality rock, varied pitches, relatively low difficulty (AD), and plenty of places to add protection, SummitPost writes.

a pile of rubble fans out at the foot of the mountain

The collapsed ridge. Photo:

Granite still unsafe

After a dry spring and a scorchingly hot summer, temperatures have decreased around Chamonix, improving conditions on the glaciers and peaks. Mont Blanc, for instance, has been okay to climb in the last two weeks, and the refuges have opened again.

“But the effect of thawing permafrost is a different story,” IFMGA guide Helias Milleiroux told ExplorersWeb. “It is now, after the big heat, when big rockslides are more likely, especially on higher granite peaks.”

Granite is especially sensitive to thawing permafrost because the ice inside the cracks in the rock melts slowly and leaves the slabs in place, but extremely unstable.

“The granite routes look fine, but they are completely unpredictable. One slab is perfectly safe, and then the next one slides down from under your feet.”

Helias Milleiroux and his sister Isis after a July climb. Photo: Helias Milleiroux


Milleiroux has been guiding in the valley all summer.

“I climbed the Freney Pillar with my sister in July and the rock was in good condition. The problem back then was that the approach route over the glacier was dry and heavily crevassed.”

According to Millerioux, that was the norm this summer: The classical routes were hard to access. “Tougher conditions on the glaciers scared off mountaineers and as a result, the mountains have been nearly empty.”

He points out that the risk now is that some people may feel safe when they are not. For the next few weeks, he recommends limestone rather than granite routes.

“The structure of limestone is different and, in the present conditions, safer,” he said.

A past climber on what used to be the Arête des Cosmiques. Photo: Juanjo for

Angela Benavides

Angela Benavides graduated university in journalism and specializes in high-altitude mountaineering and expedition news. She has been writing about climbing and mountaineering, adventure and outdoor sports for 20+ years.

Prior to that, Angela Benavides spent time at/worked at a number of local and international media. She is also experienced in outdoor-sport consultancy for sponsoring corporations, press manager and communication executive, and a published author.