Landforms Formed by Glacial Erosion

Glaciers

Mountainous and polar regions located above the snow line are covered with snow throughout the year, this snow never melts completely. These areas are called glaciers or glaciers. The height of the snow line decreases on going towards the glacier from the equator. The height of the snow line at the equator is 6000 meters. Rivers originate from these glaciers only. The speed of the rivers coming out of here is very less in the beginning. Following are some of the main facts related to glacier –

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• Snow River or Ice River : A slow flowing river in glaciers is called a snow or ice river.
• Valley Glacier : Long and narrow valleys are formed due to glaciers and snow rivers in high mountains, which are called valley glaciers or glacial valleys.
• Continental Glacier : When the ice cover spreads to the surrounding lowlands, and the entire area is covered with ice, it is called continental glacier.
• Snow Cap : High mountain peaks covered with snow are called snow caps. Glaciers originate from these peaks only.
• Ice Sheet : The layer of frozen ice or rocks on the plateau above the snow line is called ice sheet.
• Ice Berg : Blocks of ice flowing in water after breaking from a glacier or ice cap are called icebergs. They range in size from small to large. Sometimes their size is very large.

Just as various topographies are formed as a result of erosion by flowing river water, by underground water and by sea water, in the same way, erosion and exhumation occur in glaciers over time and different types of topographies are formed. happens. The brief description of these topographies are as follows –

• Topographies Formed as a Result of Glacial Erosion
  1. U shaped valley
  2. Hanging valley or Suspended valley
  3. Cirques 
  4. Aretes 
  5. Col 
  6. Horn
  7. Giant Staircase
  8. Nunatak
  9. Sheep Rock or Mesh Rock
  10. Fiord
• Topographies Formed as a Result of the Deposition Action of Glaciers
  1. Moraines
  2. Drumlin
  3. Till Ground 
  4. Outwash Plain 
     • Esker 
     • Kame
     • Ketil 
     • Hummock 
• Topography Made Under Periglacial

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A. Topographies Formed as a Result of Glacial Erosion

As a result of the erosion process of glaciers, different shapes are formed, whose details are as follows –

1. U shaped valley

No new valley is formed by glaciers. A long and deep U-shaped valley is formed by erosion perpendicular to the glacier in a pre-existing river valley.

2. Hanging Valley or Suspended Valley

The rate of erosion in the main glacier is higher than that of the tributary glacier. When a subsidiary glacier comes and meets the main glacier, the subsidiary glacier appears to be hanging at the meeting point. This is called hanging valley.

3. Iceberg or Cirques

When glaciers are removed as a result of erosion from a glacier or from a mountainous part, a topography similar to an armchair is formed. This is called Himgahvar or Sark. It is known by different names at different places. It is called Corrie in Scotland, Cwm in Wales, Karren in Germany and Kessel in Scandinavians.

4. Aretes

When two snow cavities or cirques are formed in opposite directions on a mountain, then the part between them gets eroded and forms a pointed and comb-like shape. This pointed part is called arite.

5. Girisankat (Col)

When as a result of erosion, the wall of the erite is also broken, then a hilly way is made for movement there. This path is called Girisankat.

6. Giri Shringa (Horn)

When snow cavities or cirques start forming in a mountainous area from different directions, then the top part of the mountain forms a pointed and horn-like shape. This pointed part is called Giri Shringa or top horn. Like – Matterhorn in the Alps mountain of Switzerland.

7. Himsopan or Giant Staircase and Paternoster Lake

As a result of the erosion of mountain glaciers, large ice steps or stairs are formed, which are called Himsopan or Daityasopan. Due to the disappearance of glaciers in the middle of these stairs, lakes are formed here. Which are called Paternoster Lake.

8. Nunatak

Despite the snow cover in some mountainous area, high mounds of rocks keep coming out, which are called Nunatak.

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9. Sheep Rock or Aries Rock ( Roche Moutonne )

When a large rock formation or barrier comes in the way of a glacier, the glacier starts flowing over it. Glaciers climb this barrier slowly and descend very rapidly. While ascending, the glaciers make it smooth, whereas, due to high velocity, while descending, they break the slope and make it rough and steep. Such rocky mounds look like the back of a sheep when seen from a distance. Hence they are called Bhed Shila or Mesh Shila.

10. Fiord

In high latitudes, the submerged valleys formed by glaciers are called fiords. These are mostly found on the coasts of Norway, Switzerland, Alaska, Scotland, Greenland, Chile and New Zealand.

B. Topographies Formed as a Result of the Deposition Action of Glaciers

Many types of topographies are formed by the accumulation of materials eroded by the glaciers, the details of which are as follows –

1. Moraines

Depositional moraines are formed as a result of the deposition of materials carried by snow rivers. It is mainly formed at those places, where glaciers melt and convert into water.

2. Drumlins

When the bedrock of glaciers is deposited in the form of dome-shaped mounds over a short period of time, the figures made from it are called drumlins. Their shape is like an inverted boat. Generally they are found in herds. When seen from a distance, they look like a 'basket of eggs'.

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3. Till Ground

The deposition of boulder clay by glaciers results in the formation of till plains over a wide area. The tilled plains of the prairie are an example of this.

4. Outwash Plain

When the glacier melts, its water gets divided into many streams, and spreads over a wide area to form a plain structure similar to the sheet of glacier. This plain is called the sedimentary plain or alluvial plain. The following structures are formed in the sedimentary plains –

1. Esker : In sedimentary plains, jagged ledges of rock blocks formed by streams are called Esker.
2. Kame : After the melting of the ice in the front part of the glacier, the deposits of sand and gravel appear in the form of mounds, which are called Kame.
3. Ketil : As a result of the melting of large pieces of snow, troughs or pits are formed, which are called Ketil.
4. Hummock : Many small mounds are found in the middle of Ketil, which are called hummocks.

C. Topography Made Under Periglacial

Periglaciation is formed by surface glaciers or glaciers in the polar and sub-polar regions. In this, activities like frost weathering, soil erosion etc. take place, as a result of which many structures are formed. Pingo, pulsa, thermocast, frost cliff, frost polygon etc. are formed in these structures.

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