Mechanical Weathering

What does the term "Weathering" mean and how is it related to Erosion?

Weathering means the disintegration of rocks, soil or rather everything that is on the surface of the earth and is exposed to the elements of nature. When I mention "Nature" it includes all the natural endowments like the plants and animals. The process of weathering completely transforms and alters the material that is exposed. Weathering is only a part of erosion, it loosens the material that is exposed and then the agents of erosion transport them from one place to the other. A very important difference between weathering and erosion is that weathering takes place in one place, that is the material is not transported but in case of erosion, the materials are transported.

Types of Weathering

Based on the nature and agents involved in the process of weathering, it can be classified into two types:

• Mechanical Weathering
• Chemical Weathering

here we would discuss about the former which as the name suggests involves the usage of mechanical processes in the process of alteration of rocks. It breaks the rock and that is how brings about the weathering of the rock. Let us go into a detailed understanding of what mechanical weathering is.

Mechanical Weathering

As stated earlier mechanical weathering involves the breaking down of rocks due to a kind of pressure exerted on the rock, which can be due to various reasons. The primary method of mechanical weathering is the alteration in size that the particle would go through and it would definitely grow smaller with weathering. Here are the types of Mechanical Weathering.

Exfoliation is the process wherein the rocks break in sheets along the joints that they have parallel to the earth surface. It mostly occurs when a large mass of rock is brought to the surface level as a result of tectonic movements, which thrusts the rock upwards. Even after the rock layer comes on the surface of the earth the exertion of pressure continues which results in the formation of cracks or sheet joints. Now due to pressure the rock disintegrates along the crack to expose the underlying layer of rock. This process is called Exfoliation.

Abrasion is the type of mechanical weathering which is very common in the deserts. Abrasion means that the the surface of the rock is weathered due to the action of an abrasive agent, which removes the upper layer of the rock, by friction. In the deserts the poles meant for electric wires tend to topple as the base of the pole goes through the abrasive actions and becomes weathered, resulting in the toppling down of the poles. It happens so that wind carries the sand particles that chafes against the rock and wears it down.

Freeze and Thaw Weathering is the type of weathering which is common in places where the night temperature goes down below freezing point thus freezing the weather that is collected in the cracks and crevices of the rocks. As we all know when water freezes its volume increases and as result of which the crack expands. In the morning the frozen water thaws and gives space to more water, which follows the same procedure. After repeated freezing and thawing, ultimately the rocks breaks along the crevice leading to fragmentation of the one whole rock into many rock particles.

Read about Chemical Weathering