Glaciers form in places where more snow falls in winter than melts in summer. Ov many ye, the wei of n snow pre the ol layers in dense, so ice. On the i becomes thick enough, it begins to move slowly downhill under its own weight. As glaciers flow, they carry rocks and soil with them, carving deep valleys and leaving large piles of material behind when they melt. Scientists study these features to understand how the climate has changed over long periods of time.

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