The process of disintegration and decomposition of rocks is known as “Weathering”

There are three types of weathering 

1. Mechanical weathering 

2. Chemical weathering 

3. Biological weathering 

1. Mechanical weathering: The disintegration of rocks by mechanical way and without any chemical changes is called “Mechanical weathering”. It is also called “physical weathering”. 

The process of Mechanical w eathering is in various forms, depending the types of rock. They are:

• Block disintegration: Due to temperature variation, there is continuous expansion and contraction in the rocks causing tension and stress. Later these rocks disintegrate into blocks known as “Block Disintegration”. 
• Granular disintegration: Rocks consist of several types of minerals and these minerals react differently to heat. As a result, the rocks break into different mineral grain known as “Granular Disintegration”. 
• Exfoliation: Due to the heat of the Sun, outer surfaced of rocks gets heated up, but inside it remains almost cool. This makes the rock to expand and crack. The thin layer of rocks peels off, like the peeling of an onion. This process is Galled “Exfoliation”.

2. Chemical weathering: Disintegration and Decomposition of rocks by chemical processes is called “Chemical weathering”.

In this process secondary or new minerals are developed from the original minerals of the rocks. The rain water and atmospheric gases are the main agents of chemical weathering. It is very common in humid regions.

There are four types of chemical weathering process. They are; 

• Oxidation: The rain water with oxygen reacts on rocks containing iron and produce oxides. This chemical reaction is known as “oxidation”. The common process of rusting of iron is an example of oxidation. 
• Carbonation: The rain water with carbon-di-oxide becomes a weak carbonic acid andit reacts with calcium carbonate or limestone to form calcium bicarbonate, which dissolves easily. This process is called “Carbonation”. It is very active in limestone regions. . 
• Hydration: The rock minerals take up water the increased volume creates physical stress within the rock. As a result certain minerals like feldspar and gypsum are reduced into powder. This process is called “Hydration”. 
• Solution: The rain water is able to dissolve some of the soluble minerals, such as rock-salt, gypsum, potash. This process is called “Solution”.

3. Biological weathering: The disintegration of rocks caused by plants, animals and human beings is called “Biological Weathering”.

1. Plants: The roots of the plant grow through soil and in the cracks of rocks to find water and minerals. As the roots grow deep in the rock they widen and disintegrate the rocks. This process is most prominent in thick forests and vegetative regions.

2. Animals: The burrowing animals like rats, rabbits, ants, earthworms and termites influence in the breaking up of rocks and make passages below the ground. The seepage of air and water through these passage results in rapid weathering of rocks. 

3. Human beings: Human beings play an important role weathering of rocks, through activities like agriculture, mining quarrying, oil drilling, deforestation etc.