Gradation in geography


Exogenetic forces are constantly working to bring about leveling or the gradation of land.

They attempt to achieve a condition of balance between erosion and deposition which mean a graded position.

Agents of gradation like rivers, glaciers winds, sea waves, and underground water perform their task with the help of the triple action of weathering, erosion, and deposition.

The leveling down of elevated portions of the earth’s surface is done by erosion.

The filling up of depressions is done by deposition of the eroded material transported by the external agents of gradation.

The work of gradation has two components (I) degradation and (II) aggradation.

 

Degradation

When rocks are removed by scraping, scratching and cutting as a result of the process of erosion, thereby lowering the elevation of the land, it is called degradation.

Degradation, first of all, includes the work of weathering that is the movement of scarped and scratched material aided by the great force of gravity.

It also includes the work of erosion implying the transportation of the rock material by an agent of gradation.

The increase in the movement of rock- debris increases both its erosional and transportational capacities.

 

Aggradation

Filling up of low-lying areas of depression by eroded material is called deposition.

Deposition starts when the agents of gradation lose their force or have an obstruction in their way.

As a result, eroded material is deposited in depressions which not only creates new landforms but also modifies the existing ones.

 

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