Biological weathering or chelation.

Combines the effects of plant roots and other microorganisms for example

• Plant roots growing into the rock increase internal stresses and strains causing rock disintegration via joints and crevices.
• Man through his activities such as mining and quarrying, construction, overgrazing cause large scale disintegration of rocks
• Movement/trampling of herds of animals breakdown rocks especially in nomadic communities such as Karamoja.
• Small animals such as rodents like rats. Mice, moles and squirrel make burows in rock which fcilitate physical disintegration of rocks.
• Insects such as locust and termites destroy the vegetation cover such as grass thereby exposing the rocks to agents of physical weathering