It was a beautiful morning enjoying the fresh powder on low angle slopes, but it became brutally apparent that avalanches are still a threat even when making cautious terrain choices. I was ascending Beartrap West on the heavily traveled skin track. On top of the ridge between Beartrap and Desolation Lake, I followed the final switchback of the skin track to the summit of the small knob where people usually transition. Suddenly there was a loud "WOOMPH" and I had a dizzying sensation of vertigo as I realized the snow under my feet was moving. I watched as the entire upper switchback of the skin track disintegrated under my feet and began to slide rapidly down the steep slope toward Desolation. There was nothing but air under my left ski and luckily I was able to self arrest before being pulled down with the snow. I quickly scrambled back from the edge of the slope and observed that the skin track had been ascending up a massive cornice, which had now disappeared. At least 10 other people had ascended this same skin track before me and skied down safely. There was no indication that the skin track was close enough to the edge to trigger a slide. I was unlucky enough to be the final weight that caused the whole thing to collapse. A very sobering moment that made me realize that even what may seem like a benign skin track can be a death trap in the right conditions.