A rockslide on a snow-covered mountain is called an avalanche.

Here's why:

* Rockslide: Involves loose rocks tumbling down a slope.

* Avalanche: Involves a large mass of snow, ice, and sometimes rocks, falling rapidly down a mountainside.

While both are dangerous and destructive, avalanches are more complex, involving the movement of a much larger volume of material and often triggering additional hazards like snow plumes and debris flows.