Glacial – Glacial Landforms

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  • Masses of ice moving as sheets over the land.
  • Linear flows down the slopes of mountains in broad trough-like valleys. Move basically because of the force of gravity.
  • Erosion by glaciers is tremendous because of friction caused by sheer weight of the ice.
  • Glaciers can cause significant damage to even unweathered rocks and can reduce high mountains into low hills and plains.
  • River Bhagirathi is basically fed by meltwaters from under the snout (Gaumukh) of the Gangotri glacier. Alkapuri glacier feeds waters to Alakananda river.
  • Rivers Alkananda and Bhagirathi join to make river Ganga near Deoprayag.
Erosional Landforms
Cirque
  • Found at the heads of glacial valleys.
  • The accumulated ice cuts these cirques while moving down the mountain tops.
  • Deep, long and wide troughs or basins with very steep concave to vertically dropping high walls at its head as well as sides.
  • Lake of water can be seen quite often within the cirques after the glacier disappears. Such lakes are called cirque or tarn lakes.
Horns and Serrated Ridges
  • Three or more radiating glaciers cut headward until their cirques meet, high, sharp pointed and steep sided peaks called horns form.
Glacial Valleys/Troughs
  • Glaciated valleys are trough-like and U shaped with broad floors and relatively smooth, and steep sides. contain littered debris or debris shaped as moraines with swampy appearance.
  • Elevation on one or both sides of the main glacial valley.
  • Very deep glacial troughs filled with sea water and making up shorelines (in high latitudes) are called fjords /fiords 
Depositional Landforms
  • Unassorted coarse and fine debris dropped by the melting glaciers is called glacial till.
  • Some amount of rock debris small enough to be carried by such melt water streams is washed down and deposited - outwash deposits.
  • Rock fragments in outwash deposits are somewhat rounded at their edges.
Moraines
  • Terminal moraines - long ridges of debris deposited at the end (toe) of the glaciers.
  • Lateral moraines - form along the sides parallel to the glacial valleys.
  • Ground moraines - deposits varying greatly in thickness and in surface topography.
  • Medial moraine - moraine in the centre of the glacial valley flanked by lateral moraines.
Eskers
  • Glaciers melt in summer, streams flow.
  • Very coarse materials like boulders and blocks along with some minor fractions of rock debris carried into this stream settle in the valley of ice beneath the glacier and after the ice melts can be found as a sinuous ridge called esker.
 Outwash Plains
  • Foot of the glacial mountains or beyond the limits of continental ice sheets are covered with glacio-fluvial deposits.
  • Outwash plains of gravel, silt, sand and clay.
Drumlins
  • Smooth oval shaped ridge like feature of glacial till with some masses of gravel and sand.
  • Parallel to the direction of ice movement up to 1 km length & 30m height.
  • Stoss End - drumlins facing the glacier.
  • Tail End - blunter and steeper than the other end.

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