The disintegration of rocks without any chemical change in their compost in is known as mechanical or physical weathering. The disintegration of rocks occurs mainly due to the influence of temperature variation, frost action, wind action, rainwater, etc.

A. Surface are heated and expand. During the nights the rock surfaces are cooled due to , fall in temperature, rocks contact. The repetition of exemptions and contraction causes tension and stress which leads to cracks in the rocks. Then the rocks disintegrate into i blocks. This process is known as Block disintegration, Rocks are made of different types of minerals.

So the different parts of the same rock mass react differently to temperature. This leads to differential expansion and contraction inside the rocks. The rocks break up into smaller grains. This process of weathering is, called “Granular disintegration”. Due to variat Temperature in the upper and lower layers, the outer layers of rocks peel out into the uric shells. This process of weathering is known as “Exfoliation”.

B. Frost: Rocks are disintegrated due to freezing and thawing of water in the cracks or joints in the rocks. This frost action is more important in the temperate and cold regions. The water present in the cracks of rocks freezes during the night due to fall in temperature below freezing point. When water freezes it expands by 1/10 its volume. It thaws (melts) during the day, due to increase of temperature and it contracts in volume. This alternative freezing and melting of water widens other cracks in the rocks, splits and breaks then into blocks. This is known as frost shattering.

C. Rain: Sometimes, when rain falls suddenly on highly heated rocks in hot desert numerous cracks are developed. This is just like a heated chimney of a lamp, when a drop of water falls on it. The repetition of this mechanism causes disintegration of rocks. In humid region, when torrential rain occurs, the drops strike the rock surface and loosen the particles.

D. Wind: In the deserts the wind blows with greater speed carrying with it sand and rock materials, they collide with each other or strike against the loose rock and cause weathering. In deserts the wind cause this type of weathering on a large scale.

E. Sea waves: Sea waves strike the costal rocks. Repeated striking enlarges the incipient joints. Fractures and cause breaking of rocks into small blocks. Weathering also takes place due to hydraulic pressure, abrasion and attrition caused. 

F. Slope: A steep slope helps in weathering. In mountainous and hilly area, sometimes, on account of gravity, blocks of rocks move down the slope while rolling down the slope, they strike against other block and break up into pieces.

G Gravitation: the gravity of Earth makes the huge rocks to roll towards the slope. Rolling rocks strike against each other and break up into pieces.