Question

Are physical and chemical weathering processes independent of each other? If not, why? Explain with examples.

Answer 1

No, physical and chemical weathering are not independent of each other. They are different but still interdependent. Physical or mechanical weathering processes depend on some applied forces.

The applied forces could be:

1. gravitational forces such as overburden pressure, load and shearing stress;
2. expansion forces due to temperature changes, crystal growth or animal activity;
3. water pressures controlled by wetting and drying cycles.

Chemical weathering depends on a group of weathering processes viz; solution, carbonation, hydration, oxidation and reduction act on the rocks to decompose, dissolve or reduce them to a fine clastic state through chemical reactions by oxygen, surface and/or soil water and other acids. Water and air (oxygen and carbon dioxide) along with heat must be present to speed up all chemical reactions. Over and above the carbon dioxide present in the air, decomposition of plants and animals increases the quantity of carbon dioxide underground. These chemical reactions on various minerals are very much similar to the chemical reactions in a laboratory.

These forces are interdependent. For example availability of water and heat depends on physical factors while chemical reactions depend on availability of water and heat.