This is another type of weathering caused by the action of plants and animals.
When root of trees grow in cracks and the roots penetrate the ground, they act as wedges, which cause pieces of rocks to break away from main mass.
Another way, through which Biological weathering take place is when animals like earthworm burrow the soil; they help to loosen the soil.
Also man’s activities such as road construction and farming help to promote biological weathering.