Landform

A glacier is a flowing mass of solid ice. It erodes the sides of its valley, not just the bottom, resulting in distinctive "U" shaped valleys. The rate at which it erodes is proportional to its depth, because a thicker pile of ice bears down harder on the rocks below. When a glacial tributary joins a larger glacier, the tops of both will usually flow to be at nearly the same elevation, but the bottoms will not be. This difference results in "hanging valleys," which often display magnificent waterfalls as Yosemite Falls and Bridal Veil Falls in Yosemite Valley, after the ice has melted away. A glacier can transport material at any velocity, but only while it is frozen. Where it melts, its sediments pile up into hills called moraines. Sometimes rivers flow beneath the ice, leaving sinuous mounds of sediments called eskers. Other deposits of sediment washed off the top of the glacier form steep sided hills called kames. If the glacier advances again and runs over any of these deposits, it can modify them into streamlined hills called drumlins.