How is soil formed?

Explanation

Temperature variations due to radiations of the sun, rain water, winds and living organisms influence the formation of soil from the rocks involving two processes : 1. weatheirng, and 2. Decomposition or organic matter and subsequent humification and mineralization. Breakdown of bigger rocks into small, fine soil particles is called weathering. It may occur due to physical, chemical or biological means. Under the influence of solar radiations, rocks heat up and expand. At night, these cool down and contract. Since all the parts of the rocks do not expand and contract at the same rate, cracks appear in the rocks and ultimately the large rocks break up into smaller pieces. Flow of water through or over the rocks makes the cracks bigger. On freezing, the water expands in rock creavices and and breaak the rocks. Similarlky, stong winds continue to rub against hard rocks and ercks them. Lichens, mosses and other plants also influence the formation of soil by eroding them.
Decomposition involves degadation of organic materals by bacteria and fungi of decay and leads to humification and mineralization. In this way soil is formed but very slowly.