What do you understand by the process of glaciation? What are the landforms associated with glaciation? Explain with the help of suitable examples.
हिमनदी की प्रक्रिया से आप क्या समझते हैं? हिमनदी से संबंधित भू-आकृतियाँ कौन-सी हैं? उपयुक्त उदाहरणों की सहायता से व्याख्या कीजिए।
In this question candidates need to write about process of glaciation and land-forms associated with glaciation. Give some examples of land-forms created through glaciation .
Glaciers are the mass movement of the ice that can change the entire landscape. They can sculpt mountains and carve valleys. Glaciers can move a vast quantity of rocks and sediments and creates landforms.
As glaciers move across a landscape, they alter the terrain and carve out unique formations. This process is called glaciation,
- It is responsible for many of the most recognizable landscapes on Earth.
- Glacial processes are the way that glaciers shape the land through processes of weathering, erosion, transportation, and deposition. Abrasion and plucking are the two main glacial processes of erosion.
Glacial Erosional Landforms-
- Hollow basin cut into a mountain ridge.
- It has steep sided slope on three sides, an open end on one side and a flat bottom.
- When the ice melts, the cirque may develop into a tarn lake.
- Original stream-cut valley, further modified by glacial action.
- It is a ‘U’ Shaped Valley. It at mature stage of valley formation.
- Since glacial mass is heavy and slow moving, erosional activity is uniform – horizontally as well as vertically.
- A steep sided and flat bottomed valley results, which has a ‘U’ shaped profile.
- Formed when smaller tributaries are unable to cut as deeply as bigger ones and remain ‘hanging’ at higher levels than the main valley as discordant tributaries.
- A valley carved out by a small tributary glacier that joins with a valley carved out by a much larger glacier.
- Steep-sided, sharp-tipped summit with the glacial activity cutting into it from two
- Ridge that acquires a ‘horn’ shape when the glacial activity cuts it from more than two sides.
- 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.
Glacial Depositional Landforms-
- Glacial Depositional Landforms – eskers-morains
- When the glacier reaches its lowest point and melts, it leaves behind a stratified deposition material, consisting of rock debris, clay, sand, gravel etc. This layered surface is called till plain or an outwash plain.
- Winding ridge of un-assorted depositions of rock, gravel, clay etc. running along a glacier in a till plain.
- The eskers resemble the features of an embankment and are often used for making roads.
- Broken ridges or un-assorted depositions looking like hump in a till plain.
- They are smooth oval shaped ridge-like features composed mainly of glacial till with some masses of gravel and sand.
- The long axes of drumlins are parallel to the direction of ice movement.
- They may measure up to 1 km in length and 30 m or so in height.
- The drumlin end facing the glacier is called the stoss end and is blunter and steeper than the other end called tail.
- Formed when the deposited material in a till plain gets depressed locally and forms a basin.
- They are long ridges of deposits of glacial till.
- Terminal moraines are long ridges of debris deposited at the end (toe) of the glaciers.
- Lateral moraines form along the sides parallel to the glacial valleys.
- Many valley glaciers retreating rapidly leave an irregular sheet of till over their valley floors called ground moraines.
- The moraine in the centre of the glacial valley flanked by lateral moraines is called medial moraine.
- They are imperfectly formed as compared to lateral moraines. Sometimes medial moraines are indistinguishable from ground moraines.
In glacial landforms, glacial erosion landforms occur due to scouring of land surface due to deposition of ice and snow and glacial depositional landforms is the depositions of crushed rocks and sands after the melting of glacial.