Sunday, 26 February 2017

Geography Notes on Landforms created by the Glacier

Cirque:
  • A cirque ("serk") is a bowl-shaped rock valley on the side of a mountain, often with a glacier or permanent snowfield in it.
  • Cirques are created by glaciers, grinding an existing valley into a rounded shape with steep sides.
  • The back wall of the cirque is like a high cliff and the floor is concave and huge in size. The total shape resembles an armchair.
  • When a glacier melts completely, water accumulates in the cirque and forms a lake which is known as a tarn.
U-shaped valley:
  • When a glacier is flowing through a valley in a mountainous region, the sides of the valley get eroded. Ice causes friction on the sides of the valley.
  • As the erosion of the sides is greater than that of the floor, a valley is formed with vertical sides and a wide floor. This valley is called a U-Shaped valley.
Hanging Valley:
  • Hanging valleys are often associated with valley glaciers, joining the main valley along its sides.
  • They are the product of different rates of erosion between the main valley and the valleys that enter it along its sides.
  • The tributaries are left high above the main valley, hanging on the edges, their rivers and streams entering the main valley by either a series of small waterfalls or a single impressive fall.
Fjord:
  • Steep-sided narrow entrance-like feature at the coast where the stream meets the coast.
  • Fjords are common in Norway, Greenland and New Zealand.
Moraine
  • The material transported and deposited by a glacier is known as moraine.
  • Moraine is made up of pieces of rocks that are shattered by frost action and are brought down by river.
  • Zigzag hills, with many steeps slopes, made up of long stretches of sand and gravel are called eskers.
  • The oval shaped hills of lesser height are called drumlins.
Types of moraine;
  • Lateral
  • Medial
  • Terminal
  • Ground

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