CBSE Class 9 Answered

Soil is formed by the following two processes:

i. Weathering: It is the process of breaking down of rock from the sediment. It includes physical, chemical and biological processes. Physical processes are temperature, wind, rain, water, ice, snow and glacier. Chemical processes includes hydrolysis, hydration, oxidation and reduction. Biological processes includes production of organic acids by lichens and mosses that leads to the breakdown of rock into smaller particles.

ii. Paedogenesis:  In this phase of soil formation, soil gets enriched with minerals and humus by the action of detritivores and arthropods.  The addition of organic matter is the final stage in the soil formation.