The planar surface over which an avalanche releases and slides on.
Credit: Crested Butte Avalanche Center
The bed surface can be any layer within the snowpack or the ground. Common bed surfaces include crusts or hard, old layers in the snowpack, or in many cases, avalanches slide along the weak snow that caused the initial failure.
Credit: Crested Butte Avalanche Center
Credit: Colorado Avalanche Information Center