Avalanches are caused when there is a ledge or pocket on the side of a mountain. The snow accumulates in that pocket or ledge and if it becomes too heavy for the ledge, it will tumble down the...
In snow avalanches, new snow that accumulates on top of another heavy layer of snow can begin to slide down the mountainside. The sliding mass gains momentum and size as it moves downhill.
Effects of Avalanches: The effects of an avalanche can be destruction of buildings/roads (e.g. ski lodge), Death or injury of person (frostbite, broken limbs etc.), Death or injury of animals...