What is the term for the surface the avalanche slides on?

• A. Bed surface
• B. Crown
• C. Debris
• D. Staunchwall

Answer: (A)

In avalanche terminology, the surface the avalanche slides on is the bed surface—the boundary between the moving snow and whatever is underneath, whether that's the ground or a weaker snow layer below. This interface is where friction acts as the slab glides downslope, so naming it the bed surface highlights what the avalanche is sliding over.

This term is distinct from the crown, which is the fracture line at the top where the slab initially released; and from debris, which is the snow and material left behind after the avalanche stops. It isn’t a standard term for the boundary, so it wouldn’t describe the sliding surface.