Av′alanche, a mass of snow or ice which slides down the sides of high mountains, often causing great destruction. There are various kinds of avalanches. Drift or powder avalanches are loose, dry snow, which is set in motion by the wind and rushes into valleys in the form of great dust-clouds. They usually occur in winter and are very dangerous, because of their suddenness, often suffocating men and animals and overturning houses by the compression of the air which they cause. Another kind of avalanche is like a landslide. The melting of the snow in spring makes the soil slippery, and great masses of snow are carried down the mountains by their own weight, taking trees and stones with them. If they come to a precipice in their course, as they often do, they are hurled with tremendous force into the valley beneath, destroying whatever is in their path. Ice avalanches often occur in summer. They are masses of ice which detach themselves from the mountain glaciers, commonly in July, August and September. Nine great Alpine avalanches, which destroyed 447 lives, are recorded between the years 1578 and 1827.
For works with similar titles, see Avalanche.