Glacial Deposits
Thousands of years ago, snow fell year-round over large areas of Asia, Europe, and North America. Over time, the weight of snow from the top added pressure below. Slowly, the snow turned to ice. Glaciers were formed. The ice in some of these glaciers was almost 1000 m thick. The weight of the ice became so great that it pushed and dented the land.
These moving masses of ice were great forces of erosion. Huge amounts of soil and rock were pushed ahead of the ice and carried along in the glacier's bottom layers. After thousands of years, the ice began to melt. When the ice melted, it left the land changed.
These moving masses of ice were great forces of erosion. Huge amounts of soil and rock were pushed ahead of the ice and carried along in the glacier's bottom layers. After thousands of years, the ice began to melt. When the ice melted, it left the land changed.
The rocky sediment deposited by a glacier is known as till. Till may be fine soil, sand, gravel, boulders, or sharp rocks. Some till is picked as a glacier scrapes Earth's surface. The glacier drags till along its icy base.
A glacier also deposits till at its front. Such deposits are called moraines. Long Island, New York is a moraine left when a huge ice sheet melted. Streams flow through tunnels in melting glaciers. The streams deposit sand and gravel in ridges. These winding ridges are called eskers.