EXTERNAL PROCESS & WEATHERING AND ITS TYPES

External process

      It  refers to the external phenomena that occur on or above the earth’s surface. External processes shape the relief created by internal processes. External agents carry out this process: water, ice, wind, atmosphere and human beings. They include all the changes that alter or wear down the rocks and deposit materials resulting from erosion.

 

Weathering 

Weathering is the fracturing or disintegration and decomposition of rocks by natural agents. It is a static process. There is no movement of weathered material except where the pieces fall due to the force of gravity. 

Weathering is classified into three types:

1. Physical or Mechanical Weathering 

2. Chemical Weathering 

3. Biological Weathering

1. Mechanical Weathering Mechanical weathering is the physical disintegration of rocks due to factors like heat, water and frost. Small pieces or particles of rock prise off from the rock surface. 
   
2. Chemical WeatheringChemical weathering is the rotting or decomposition of rocks, under the influence of atmosphere and water. This type of weathering is most common in equatorial and tropical regions where there is enough moisture and heat to start off chemical reactions within rock masses.
3. Biological Weathering Biological weathering is a form of weathering caused by growth of roots and burrowing of animals. Plants roots are the most efficient agents of the biological weathering as they give off acids that contributes to break down of rocks.