Avalanches
masses of snow or ice that slide or roll down the declivities of high mountains, and often occasion great devastation. They have various names, according to their nature. Drift or powder avalanches consist of snow, which, loose and dry from strong frost, once set in motion by the wind, accumusuddenly lates in its descent, and comes suc into the valley in an overwhelming dustcloud. Avalanches of this kind occur chiefly in winter, and are dangerous on account of their suddenness, suffocating winter, and are dangerous on men and animals, and overturning account of their suddenness, suffocating houses by the compression of the air which they cause. Another kind of avalanche resembles a landslip. When the snow begins to melt in spring, the soil beneath becomes loose and slippery; and the snow slides down the declivity by its own weight, carrying with it soil, trees, and rocks. Ice avalanches are those that are seen and heard in summer thundering down the steeps-e. g., of the Jungfrau. They consist of masses of ice that detach themselves from the glaciers in the upper regions. They are most common in July, August and September. Nine great Alpine avalanches , which cost 447 lives, are on record between 1518 and 1879, the most destructive being one of 1827, which swept away half the village of Biel, in the upper Valais, with 88 inhabitants .