An avalanche is a sliding mass of snow, or ice, or wet earth and stones. An avalanche of earth and stones is a kind of landslide. It can happen even in regions without snow. A steep mountainside or bluff becomes thoroughly soaked with water, or is weakened in some other way. The earth can no longer stand in such a steep slope without sliding, and an avalanche begins.
This kind of avalanche is most common in the spring, when winter snow and ice melt and soak the ground below. It may also occur where man digs a roadway or mine along the base of a steep mountainside. This kind of landslide has often blocked mountain valleys and thereby created large lakes.
