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Glacial Landform Features

During the last Ice Age, glaciers covered about a third of the Earth's surface compared with about 10 percent today. Glaciers move, and it is this action -- called glaciation -- that creates landforms. Glacier movement erodes the surface beneath it, creating one type of landform feature. They also pick up rocks and deposit them in other places, creating other landforms. Many of the landscape features found in North America and Europe are the result of these two types of Ice Age glacier action.

Cirques
- A cirque is one of the larger glacial landforms cause by erosion. It is a bowl-shaped depression with steep sides carved out of a mountainside. Some cirques fill with water to form a tarn, which is a name for a small lake. In some mountainous regions, the glacier creates two or more cirques side by side. Between these, steep, sharp ridges form, called arretes. When the walls of three cirques meet they often form a mountain peak, called a "horn." The Matterhorn, in Switzerland, is a famous example of this kind of landform.
Kettle Lakes
- A kettle lake is formed when a sizable chunk of the main glacier breaks off and is buried under "till" from the main glacier. This is a mixture of finely-ground rocks, boulders and sand. Underneath the till, the glacial ice melts and creates a depression in the landscape that eventually fills with water to form a lake. One of the most famous kettle lakes in the world is Walden Pond in Massachusetts. It has steep sides, coves and two spots of extreme depth, which are characteristic of a kettle lake. Its fame comes not so much from the fact that it is a glacial landform, but because it is the setting for Henry Thoreau's influential philosophical study, titled "Walden, or Life in the Woods."
Drumlins
- Drumlins are tear-shaped hills that formed beneath the glacier, and are created by the glacier depositing rocks rather than eroding the landscape. A drumlin landscape is characterized by soft, rolling hills and is often called a "basket of eggs" landscape. The position of the drumlin tail, or pointy end, indicates the direction the glacier was going in, as it moves from the blunt toward the point and vary in length from 200 feet (60 meters) to just over half a mile, or one kilometer.
Valleys
- The downward flow of a glacier through an existing stream valley creates a valley glacier. With the force of erosion, these valley glaciers turn V-shaped valleys into U-shaped ones that resemble a trough in shape. Where a small glacier erodes the terrain above the main valley, it creates a small trough, which is called a "hanging valley." When a glacier creates a valley that runs all the way down to the sea, and the valley fills with sea water, this landform is known as a "fjord."

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