Index >> Microbes and Lithosphere>> Biological Weathering

Lower forms of plants (algae and pioneer organisms) like lichens inhabit the bare rocks, since lichens can grow in any extreme habitat owing to their symbiotic relationship.

These organisms release carbon dioxide (respiration) which combines with water (moisture) to form carbonic acid.
The acid helps in decomposing the soil minerals to form clay. This is a long-term process. As these pioneer organisms die, they get decomposed and add humus to the rock surface thus facilitating other chemoorganotrophs to grow.

Now there is a heap of life growing over the rock and this leads to the formation of crevices on the rocks (due to the acid produced by the growth of the organisms). Higher plants start growing in these crevices adding to the organic matter. Thus the parent rock becomes weathered and turns into soil. This process happens only in terms of years.