(i) Relief, parent rock or bedrock, climate, vegetation and other forms of life and time are important factors in the formation of soil. (ii) Various forces of nature such as change in temperature, actions of running water, wind and glaciers, activities of decomposers, etc. contribute to the formation of soil. (iii) Chemical and organic changes which take place in the soil are equally important. (iv) Soil also consists of organic (humus) and inorganic materials.