Biological Weathering

Living organisms like lichens, mosses, etc. influence the formation of soil.

(a) Lichens : They live on rocks and produce acids. The acids corrode the surface of rocks to form thin layer of soil.

(b) Mosses : Mosses later grow on such surfaces and cause the rock to break up further.

(c) Roots : The roots of trees enter the cracks and provide anchorage. In due course, roots grow bigger and force the cracks to widen.