Avalanche (Fr. avalanche or analange), a mass of snow precipitated from mountain sides to the lower levels. Avalanches are common in the Alps and Apennines, and several different forms of them are described. The drift avalanche is the light, dry snow swept from the mountains by strong winds, and accumulated in the valleys, sometimes to such depths as to bury the villages it falls upon. More destructive is that formed by the damp, cohering snow, which, beginning in a small rolling body, gathers with every turn increased proportions and velocity, and taking up in its progress loose rocks and earth, or the shattered limbs of trees, sweeps off not only houses and villages, but the very lands on which they stand. It is said that in the year 1500 100 men were buried by such an avalanche in the Great St. Bernard; and in 1624, in Italian Switzerland, 800 soldiers were thus engulfed, many of whom, however, were afterward dug out alive. The villages in the high valleys of the Rhone have been particularly exposed to these disasters.

In 1827 the village of Briel in Valais was almost entirely covered with an avalanche.

The rolling avalanches sometimes change in their descent to sliding masses, and these take in their progress every movable body, down to the solid rock of the mountains. Hills of gravel and loose rocks, covered with forests and dwellings, are thus carried down to lower levels, and in cases of vineyards thus removed, intricate questions of proprietorship have arisen. Ice avalanches are produced by the breaking of masses of ice from moving glaciers. (See Glacier).