Cold Environments: Glacial Landforms

Erosional Landforms
1. Corries/Cwm/Cirque
  1. Corrie is also known as a Cwm (Wales) or a Cirque (France) and is an enlarged hollow on a mountainside.
  2. Steep back wall and sides, generally hollow and very deep and may contain a small lake called a tarn.
  3. The front of a corrie often has a raised rock lip, which helps explain the presence of the tarn.
2. Arêtes
  1. Two neighbouring glaciers cut back into a mountainside-each one eroding a corrie-the ridge between the two corries becomes narrower.
  2. This is a knifed-edged ridge called an arête that are common in both present-day glacial landscapes, and post-glacial landscapes.
3. Pyramidal Peak
  1. When three or more corries erode back-to-back, the ridge then becomes an isolated peak called a pyramidal peak.
4. Glacial Trough
  1. This is, in effect, a U-shaped valley. They tend to be steep-sided and flat-bottomed. They are also generally straight, because of their immense power and inflexibility of the large glaciers that gouge them out
  2. A valley glacier will just cut through any previously existing interlocking spurs to form truncated spurs up the valley side.
  3. If a glacier encounters weaker bedrock, or if a tributary joins the main valley which increases volume of ice, there might be enhanced erosion in parts of the trough (overdeepening). Localised enhanced erosion can form a narrow, but deep, ribbon lake
  4. When main glacier melts, tributary glaciers are left hanging, and when they melt a hanging valley is formed
  5. Resistant bands of rock on valley floor can lead to formation of roche moutonnee
5. Roche Moutonnee
  1. Formed when a glacier flows over a band of resistant rock
  2. Approximately 20 meters in height, and 10 meters in length
  3. Strations on upstream side dues to abrasion, and polishing due to rock flour
  4. Plucking on downstream side
Depositional Landforms
1. Moraines
  1. Lateral Moraine consists largely of frost shattered rocks that have fallen onto the glacier from the valley sides
  2. Medial Moraine is when a tributary glacier joins the main glacier, and two lateral moraines join up.
  3. Englacial Moraine is moraine that has been trapped inside the glacier for many years
  4. Ground Moraine is the rock material that grinds along at the base of the glacier.
  5. Terminal Moraine is the moraine that marks the furthest the glacier has travelled.
  6. Recessional Moraine is formed when a glacier retreats, then after a long time starts to move again, gathering moraine as it travels. This moraine is then deposited here and this is known as recessional moraine. It marks a temporary halt in the retreat of the glacier.
2. Outwash plain
  1. Lies beyond the terminal moraine
  2. A vast expanse of sand and gravel-deposited by braided meltwater rivers from the glacier.
3. Till
  1. The material deposited/dumped on the ground when a glacier retreats.
4. Drumlins
  1. Upstream side (stoss) is the steep sided
  2. The downstream side (lee) is the gentle sloping side.
  3. Egg-shaped hillocks that usually occur in clusters (swarms) in low-lying valley bottoms.
  4. Consisting of a mixture of boulders and clay (ground moraine)
  5. Thought to have been a result from the moulding of rock debris on the valley floor by ice moving over it.
  6. Approximately 10 meters in height, and 40-50 meters in length
  7. Steep upstream, and long slope downstream

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Cold Environments: Glacial Landforms

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	Created by Andrew_Ellinas almost 11 years ago