Biological weathering is the disintegration of rocks as a result of action by living organisms.

Biological weathering is the disintegration of rocks as a result of action by living organisms because-

 1. Roots of trees and other plants penetrate into the soil and grow in size. Thus, they exert pressure on rocks and make the cracks wider and deeper. 

2. Some plants grow within fissures and lead to disintegration. 

3. Microscopic organisms such as algae, moss, lichens and bacteria grow on rock surface and produce chemicals, they react on outer layers the rocks and break them.

4. Man known for his economic and technological development becomes the most powerful weathering and erosion agent. Mining, blasting, construction of roads, railways etc., result in fast disintegration of rocks. 

5. There are some barrowing animals like rats, when they barrow, rocks are broken.