Denudation
The process of wearing away the earth causes a general lowering and leveling out of the surface.
This process is called denudation and is carried out in 4 phases:
o Weathering: Gradual disintegration of rocks by atmospheric or weather forces.
o Erosion: Active wearing away of earth’s surface by moving agents like water, wind, glaciers, etc.
o Transportation: Removal of eroded debris to new positions.
o Deposition: Dumping of debris in a certain part of the earth, where it may accumulate to form new rocks.
All 4 phases of denudation are taking place simultaneously in different parts of the world at different rates depending upon the following factors:
LOCAL CLIMATE:
- As there are different climatic regions on the earth’s surface owing to thermal gradients created by latitudinal, seasonal and land and water spread variations, the exogenic geomorphic processes vary from region to region.
- Within different climatic regions, there may be local variations of the effects of different climatic elements due to altitudinal differences, aspect variations and the variation in the amount of insolation received by north and south facing slopes as compared to east and west-facing slopes.
STRUCTURE OF ROCKS:
- Climatic factors being equal, the intensity of action of exogenic geomorphic processes depends upon the type and structure of rocks. The term ‘structure’ includes such aspects of rocks as folds, faults, orientation and inclination of beds, presence or absence of joints, bedding planes, hardness or softness of constituent minerals, chemical susceptibility of mineral constituents; the permeability or impermeability, etc.
NATURE OF RELIEF:
- The differences on the surface of the earth like variations in crustal strength and thickness though originally related to the crustal evolution continue to exist in some form or the other due to differences in the type and structure of earth materials, differences in geomorphic processes and in their rates of operation.
INTERFERENCE BY MAN:
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Human beings by disturbing vegetation, ploughing and cultivating soils, also help in mixing and creating new contacts between air, water, and minerals in the earth materials.