Science Matters: Glaciers (PB)

A large mass of ice in a very cold region is called a glacier. Glaciers form in areas where it is so cold that snow does not melt. Layers of snow build up over many years and become ice. Glaciers can be as large as an entire continent. They can also fill a small valley between mountains. Over time, the glacier's weight and gravity cause it to move. Most glaciers move very slowly.