III. Biological Activity

It includes the role of plants and animal in promotion of both physical and chemical weathering. Burrowing and wedging by organisms like earthworms, termites, rodents etc., help in exposing the new surfaces to chemical attack and assist in the penetration of moisture and air. Human beings by disturbing vegetation, ploughing and cultivating soils, also help in mixing and creating new contacts between air, water and minerals in the earth materials. Tree roots can occasionally be shown to have forced apart adjacent blocks of rock. Decaying plant and animal matter help in the production of humic, carbonic and other acids which enhance decay and solubility of some elements.