Formation Of Soil
Soil of Class 7
Soil formation process is very slow it takes several of years to form soil and it is a non-renewable resource. Soil formation start millions of year back near the surface of the earth and it is initiated by the rocks presents in the earth surface, the rocks present in the surface broken down to form a small particles by various physical, chemical and some biological processes. This process in known as weathering and results in formation of fine particles of soil.
Due to weathering all the parent material undergo chemical and physical decomposition and transformation. In general minerals that are formed or produce by the action of high temperature and pressure are less resistant to weathering, while minerals which are formed at low temperature and pressure are more resistant to weathering. Weathering is usually confined to the top few meters of geologic material, this is due to physical, chemical, and biological stresses generally decrease with depth. Physical disintegration start with rocks that have solidified deep in the earth and exposed to lower pressure near the surface and they swell and become unstable. The decomposition of chemical weathering rates double with each rise of 10°C in temperature but is mainly dependent on water to effect chemical changes. Rocks that will decompose in a few years in tropical climates will remain unaltered for millennia in deserts.