Loose Snow Avalanches

A loose snow slide pours from a mountain in Denali National Park into the valley. (webshots.com)

Loose, or point-release, avalanches occur on slopes where the snow has simply lost its ability to remain on the slope. This is due to cohesionless snow sloughing off the surface, and picking up more snow as it falls down-slope. As the first particles of snow begin to release on the steeper aspects of the slope, they collide with lower particles, and create a fanned, triangular appearance on the slope. This type of avalanche generally occurs on slopes of 35 degrees or more and typically involves only the upper layers of the snow pack.

*How An Avalanche Forms