Glaciers

Changing Earth’s Surface

5 Agents of Erosion

Gravity Running Water Glaciers Waves Wind

Glaciers

Glacier – any large mass of ice that moves slowly over land.

Two Types• Continental

• Valley

Continental Glaciers

A glacier that covers much of a continent or large island.

Ice Age

Continental glaciers have covered larger parts of Earth’s surface.

Valley Glaciers

A long, narrow glacier that forms when snow and ice build up high in a mountain valley.

Valley Glaciers

Once the depth of the snow and ice reaches more than 30-40 meters, gravity begins to pull the glacier downhill.

Valley Glaciers

Rate – a few centimeters to a few meters per day.

Glaciers Shape the Land

Erosion Deposition

Glacial Erosion

Plucking – the process by which a glacier picks up rocks as it flows over the land.

Glacial Deposition

When a glacier melts, it deposits the sediment it eroded from the land, creating various landforms.

Till

The mixture of sediment that a glacier deposits directly on the surface.

Clay, silt, sand, gravel, and boulders

Deposition Landforms

Moraine• The till deposited at the edges of a glacier

forms a ridge.

Terminal Moraine• The ridge of till at the farthest point reached

by a glacier

• Long Island NY is a terminal moraine from the last ice age.

Deposition Landforms

Kettle• A small depression that forms when a chunk

of ice is left in glacial till.

• Kettles often fill with water. Many found in Minnesota