Natural Resources — Science STD 9 — Question

Biological weathering: Is done by living organisms such as lichens and bryophytes. Lichens growing on rock surface extract minerals from the rocks. This creates small crevices at places where a thin layer of soil builds up. Mosses grow over these crevices causing deepening of crevices and results in the buildup of more soil inside them. The roots of short lived herbs also passes into them and the cracks gradually widen and cause slow fragmentation and eventually pulverisation of rocks.