Question

Write a note on weathering classify and explain.

Answer 1

1. Weathering is the disintegration and decomposition of materials of the earth’s crust by their exposure to atmosphere.
2. Movement of huge volumes of weathered rock material down the slope due to gravity is called mass movement or mass wastage.
3. The nature and magnitude of weathering differs from place to place and region to region
4. There are three types of weathering called physical weathering, Chemical weathering and Biological weathering.

• Physical weathering:

1. It is the breakdown of rocks without changing their chemical composition, through the action of physical forces.
2. The constant freezing and thawing of rocks during the night and day leads to expansions and contractions of rocks.
3. Exfoliation, block disintegration, granular disintegration, etc., are the different types of weathering.
4. The alternate heating and cooling on rounded rock surfaces leads to the peeling of rocks, layer by layer. This is called exfoliation.
5. Granular disintegration takes place in crystalline rocks where the grains of the rocks became loose and fall out.
6. Block disintegration is caused due to repeated expansion and contraction of rocks day and night.

• Chemical weathering:

1. Disintegration and decomposition of rocks due to chemical reactions is called chemical weathering.
2. Chemical weathering takes place through the processes of oxidation carbonation, solution and Hydration.
3. Oxygen in the atmosphere reacts with the iron found in rocks, forming iron oxide. This process is known as oxidation.
4. Carbonation in the mixing of water with the atmospheric carbon di – oxide forming carbonic acid.
5. Solution is the process of dissolution of rock substances in water. This results in the loosening of the rock particles.
6. Certain chemicals in the rock enlarge in size in humid conditions, resulting in the development of cracks and the rock wears down. This is known as hydration.
7. Biological weathering: Biological weathering occurs due to the penetration and expansion of plant roots, earthworms, burrowing animals (rabbits, rats) and some human activities.