ABSTRACT
Glaciers form when in the course of a typical year more snow is deposited than is wasted, that is, when accumulation exceeds ablation. Generally, accumulation is made up of snowfall, wind drift and avalanches, sometimes also of rime and frost or the freezing of rain or melt water in the snow pack. Ablation may be caused by melting, sublimation or wind erosion, loss of ice by avalanches or ice falls, or by the calving of icebergs, i.e. the breaking off of ice into an ocean or lake.
