Physical Weathering of Rocks


Physical Weathering of Rocks (Mechanical Weathering)

Physical weathering is a process in which rocks are broken up into smaller particles without any chemical change.

This is a process of physical disintegration of rock into smaller pieces

Physical weathering is carried out in different ways in different types of areas.

 

Block disintegration

Physical weathering is carried out in different ways in different types of areas.

Successive heating and cooling cause rock expansion and contraction.

In hot desert regions, daytime temperatures are high, while nights are very cold.

This high diurnal temperature range causes rock expansion and contraction that tend to enlarge joints.

And then, rocks disintegrate into smaller pieces.

The process is termed as block disintegration.

 

Exfoliation

Rocks are usually weak heat conductors.

As a result of extreme heating, the rock’s outer layers expand quickly while the inner layers remain unchanged.

Due to this, the outer layer of the rock subsequently peels off from the rock’s main mass.

The process of rock peeling is very similar to the peeling of an onion’s successive layers.

This process is termed as Exfoliation.

Examples of exfoliation: Dolerite blocks of rocks in Singhbhum(Bihar), Granite domes of Mahabalipuram.

 

Frost Action:

This process occurred in cold climates.

The rocks get split into parts due to continuous freezing and melting of water inside their joints.

When water is converted into ice its volume increased by 10 percent.

In cold regions s, through this process rocks are broken down into small particles.

This process is termed as frost action.