Glaciers are made from fallen snow that are compressed together into large ice masses. Gaciers are formed when snow remains in one location long enough to transform into ice. Glaciers are the largest reservoir of fresh water. Approximately 10% of the earth is covered by glaciers.
They constantly move under their own weight. For it to remain in a constant size, there must be a balance between income (accumulation) and outgo (ablation). For glaciers to be formed in the first place, accumulation must be more than ablation of snow over a period of many years.
