In the topic erosion by running water, we need to have a proper understanding of the words erosion and running water. So, erosion is a geological process through which earthen material (including soil, rock fragments, etc.) is worn away from one location on the Earth’s crust and transported to another location by natural forces such as wind or water. The word running water basically stands for the flowing water, such as river, seas, stream, etc.
The running water cause erosion in four ways: -
1) Chemical action: In chemical action, the chemical decay works along joints and cracks and thus helps in breaking the bedrock.
2) Hydraulic action: It is the erosion that occurs when the motion of water against a rock surface produces mechanical weathering. Here the moving water current flows against the bunks and bed of a river, thereby removing the rock particles. At the bottom of waterfalls, the channels are eroded at an enormously rapid rate by the hydraulic action.
3) Abrasion: The flowing water uses rock fragments such as pebbles, gravels, and sands as a tool for scratching and grinding the side and floor of the valley. This process of erosion is called abrasion.
4) Attrition: it is the erosion that includes the mechanical breakdown of loads running along the moving water due to the collision of particles with each other. The attrition causes the rock fragments to become more rounded and smaller in size.
EROSION BY WIND
1) Deflation: Lifting and removal of loose material by wind are called deflation. By this process, the land surface is gradually lowered. In many desert areas, deflation produces hollows or basins with their bottoms at the water table. Such basins containing some water, which are known as “oases”.
2) Abrasion: During dust storms, the wind carries minute grains of sand in suspension. They travel in a great hurry and collide against the rock masses and cause erosion. In this process, the sand grains are used as tools for eroding rocks is called abrasion.
3) Attrition: The particles that travel with wind collide against one another. These mutual collisions lead to their further breakdown and the process I called attrition.
The Glacier refers to the large crystalline ice, which is formed by the influence of pressure and moisture, the snowflakes change into a granular ice mass. When the ice becomes so thick that the lower layer becomes slippy, downhill snowfall occurs and an active glacier comes into existence.
There are three types of glaciers:
1) The valley glaciers (Mountain glaciers)
2) Piedmont glacier (these are intermediate in form, they are formed at the foot of the mountain.)
3) Ice sheet ( These are huge covers of ice and are also known as Continental glaciers.)
In simple language, the erosion or Degradation process occurs due to one of the geological agent's glaciers, such erosion is called glacier erosion.
Erosion by glacier takes place due to:
1) Plucking: Water flowing along the bottom of the glacier and enter the cracks of the rocks and freezes under it, which is known as freeze-thaw weathering. Since the glacier flows downhill so, this flow pulls the loose pieces of rocks with it. This phenomenon is called plucking.
2) Abrasion: These loose, broken rock pieces, scrape the glacier bed like sandpaper, taking more broken rock pieces along with it, which is known as abrasion. This is also known as rasping.
3) Avalanching: Avalanching is the process of mass-wasting. Along the margins of a valley glacier, the valley side is scrapped and blocks are broken down into smaller pieces, which are carried away by the glacier along with its downhill flow. This leads to undercutting of the side of the valley and creates an avalanching, which brings great quantities of rock waste onto the top of the surface of the glacier.
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