Glacial landforms with mapped examples
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Snow collects in hollows high in the mountains and over time compacts into ice. As the ice moves downhill due to its weight and melting water underneath, it erodes the landscape through plucking and abrasion. This action deepens and steepens the hollows, forming cirques or corries, and creates sharp-edged ridges called arêtes between corries. When three or more cirques cut into the same mountain, they form a pyramidal peak with steep, angular faces.
Glacial landforms with mapped examples
- 1. A U-shaped valley This is an example of a U-shaped valley in Great Langdale in the Lake District, and is in the format of an Os Map. A U shaped valley is formed by a valley glacier. A valley glacier will completely fill a valley in an upland area. By doing this, it has far more power to erode the whole valley than the original river which only flowed across the valley floor. As the glacier moves down a valley, its huge power erodes any rock in its path. It does not need to go around crops of harder rock, but simply remove them. Flat bottom Steep valley sides The valley which used to be a V- shaped valley with a river in the bottom now has steep walls of bare rock for its sides and a flat bottom. It is also straighter than it was before glaciation.
- 2. Arête between two corrie glaciers Cirque Steep arm shaped hollow on the side of a mountain. A Cirque or Corrie This is an example of a cirque in Striding Edge, Cumbria. There are steep contour lines all around the cirque which told me that there was a hilly landscape. Cirques began to form at the start of the ice age when snow accumulated in hollows on hillsides. This snow turned into ice, and the ice moved downhill. Freeze- thaw and plucking loosened and removed material from the back of the hollow, creating a steep back wall. 1. Snow collects in hollows high in the mountains. 2. Snow compacts to form ice. 3. The weight of the ice causes it to move, helped by melting water underneath. 4. Ice has a rotational movement towards the lip of the hollow 5. Plucking and abrasion by the ice deepens the hollow 6. Steep back walls are also produced. 7. It is likely that several corries will be forming around the mountain top each producing steep back walls. 8. The Arête ridges form between the corries.
- 3. Pyramidal peak Os version of a pyramidal peak A Pyramidal Peak This is an example of a pyramidal peak in Hafod Garregog, Gwyn. Pyramidal peaks form when three or more cirques cut backwards into the same mountain. This is continually sharpened by frost action and plucking. Steep sided, angular faces The contour lines are very close together at this point, which tells us that a pyramidal peak is here.
- 4. A Truncated Spur This is an example of a truncated spur in Great Langdale, Cumbria. Truncated spurs are rounded areas of land which have been cut off. They are often rounded at the top but steep at the bottom. They are formed when glaciers move through the main valley and cut off spurs. Truncated Spur The contour lines are close together, which shows that the land is steep and hilly. This signifies that there might be a truncated spur here.
- 5. A hanging valley This is an example of a hanging valley in Patterdale, Cumbria. A hanging valley is a tributary valley that enters the side of a U shaped glaciated valley. Originally the 'hanging' valley would have joined the main valley in a normal way, its streams or rivers flowing into the main valley at the same level. The main valley was made deeper by glaciation, but the side valleys were left at their original level. When the ice melted they were no longer level with the bottom of the valley due to the deepening which had occurred. They appear to 'hang' on the steep sides of the new valley, their streams flowing into the main valley through waterfalls. A Hanging Valley
- 6. Arête This is an example of an Arête in Helvellyn, Cumbria, and is in the format of an OS map, and a 3D image. Arêtes form when, if two corries develop back to back, they erode sideways towards each other. The piece of land between them gets narrower until a knife edged ridge, called an arête, is formed. An Arête Contour lines are close together where an Arête is found. This Arête is steep edged and is like a knife. You can see three arêtes meeting forming a Pyramidal peak.
- 7. Arête This is an example of an Arête in Helvellyn, Cumbria, and is in the format of an OS map, and a 3D image. Arêtes form when, if two corries develop back to back, they erode sideways towards each other. The piece of land between them gets narrower until a knife edged ridge, called an arête, is formed. An Arête Contour lines are close together where an Arête is found. This Arête is steep edged and is like a knife. You can see three arêtes meeting forming a Pyramidal peak.