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Geomorphic agents and processes notes

Geomorphic agents and processes
There are certain processes viz, exogenetic and endogenetic acting upon the earth's surface. The Geomorphic agents and processes are very significant to know about as because they are resulting in the formation of various landforms on the surface of the earth.

The geomorphic agents are those which are responsible for creating certain reliefs. These agents may be water, wind, waves, glaciers etc. And the geomorphic processes are those which shape the earth by creating certain landforms with the help of these agents.

Exogenetic processes are also called destructional processes as they are only engaged in destructing the various relief features on the earth. These processes perform three face work and they are erosion, transportation and deposition. The Geomorphic agents and processes notes that we are going to discuss today, generally includes the work of erosion, transportation and deposition.


Geomorphic agents and processes notes 

1. Erosional work :
(i) Corrosion - It involves the dissolution of the soluble material through the process of disintegration and decomposition of carbonate rocks. The dissolution of soluble materials and minerals from the rocks takes place through the process of solution. It further depends on the nature of rock, solubility of solids, contact type of solvents and solids and ratio between volume of solvents and solids.

(ii) Abrasion - It involves the removal of the loosened materials of the rocks by different erosional processes in differentiate manner. The degree of abrasion depends upon various factors like the nature of erosional tools, nature of erosional processes, nature if geomaterials, force of erosional processes and many more.

(iii) Hydraulic action - It involves the breakdown of rocks, due to the exertion of the pressure by currents of water and waves of sea. This action is the mechanical loosening and removal of material of rocks by water alone. The chemical erosion, abrasion and hydraulic action are so much related to each other that each of these actions cannot successfully operate without the other.

(iv) Attrition - It involves the wear and tear of the erosional tools. The cubbles, pebbles and bolders while moving downwards with water, gets collide against each other and are fragmented into smaller pieces. They are so much broken down to pieces that they get transformed into fine particles of sands and gets transported down in suspension.

(v) Deflation - It involves the removing, lifting and blowing away loose and dry particles of land and dust by winds. The long and continuous deflation removes most of the loose materials and and large depression know as blow out are formed.

2. Transportational work :
(i) The processes like floatation, suspension, solution, saltation and traction accomplishes certain transportational work.

(ii) Running water transports the sediments through traction, suspension and solution. 

(iii) The process of saltation involves the transportation of load with currents of water, where the load moves downwards through the valley floor. It works in an extremely slow manner.

(iv) Traction involves the downstream movement of the loose materials of the valley floor. The load are usually gravel, pebbles, cobles and bolders.

(v) The soluble materials get dissolved in water and become invisible and are transported downstream through the method of solution.

(vi) The materials get dissolved in a suspended form through groundwater.

(vi) The transportational work of sea wave differs from the other agents of transportation. The materials get transported from coast towards the sea and again from the sea towards the coast.
(vii) The materials involved in the transportational work of sea waves ate sand, silt, gravels, pebbles, cobles and bolders.

3. Depositional work :
(i) The deposition of the sediments by the streams depends upon a number of factors like decrease in channel gradient, decrease in stream velocity, decrease in volume and discharge of water, obstruction in channel flow, increase in sediment load, and spreading of river water over large areas.

(ii) Depositional work by the streams, is carried with an decrease in the velocity of stream, which reduces the transporting capacity of the streams and as a result it leaves additional sediments to settle down. Sedimentation takes place in the flood plains, river beds and river mouths.

(iii) Depositional work by groundwater, takes place when water becomes obstructed or over saturated. The groundwater receives more solutes, due to the continuation of the chemical erosion of carbonate rocks. As the movement of the groundwater is slow, it cannot carry enough sediments. As a result sedimentation and chemical erosion takes place together. Large size sediments gets easily settle down, while the fine sediments are kept in the suspended form.

(iv) Depositional work by sea waves, is the most variable and temporary in character because, the currents bring the sediments seawards and deposit them at lower segments of wave cut platforms. These sediments are again brought back to the coast. When an equilibrium level is achieved between the incoming supply of sediments and removal of sediments, a profile of equilibrium is achieved.

(v) Depositional work by wind, is very significant because, features like sand dune and loess are formed. The sediments get deposited due to the decrease in the wind speed and obstruction caused by forest, swamps, lakes, rivers, walls and many more. Sands get deposited on both windward and leeward side of these obstructions. The accumulated sands on other side of the obstruction are called sand shadows, while the accumulated sands between the obstructions are called sand drifts.

(vi) The depositional work by glaciers,  which carry the rock debris are called glacial drifts which contains till, ice contact stratified drift, outwash and many more. They are divided into englacial debris, that exist on the surface of the glacier ; superglacial debris, that exist on the surface of the glacier ; subglacial debris, that exist on the base of the glacier.

These erosional, transportational and depositional work creates certain landforms of the earth which are very significant. They are intimately interrelated to each other in the way that, none can be carried and worked alone with the help of other.

In the Geomorphic agents and processes notes we got the significance and specific details about how erosional, transportational and depositional processes are carried out. The origin of any form of landforms are the only outcome of these three face works of geomorphic processes.

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