Soil formation occurs by a process called weathering off rocks. For this breaking down of rocks, a number of factors are needed like,
● Sun: - During daytime sun heats up the rocks due to which a little bit of expansion of rocks occurs. At night when the temperature falls rocks tend to contract, due to this simultaneous and subsequent heating, and cooling cracks are formed inside the rocks. This phenomenon can be easily observed in hilly areas during the rainy season. After the rain when the sun emerges it heats up the wet and cool mountains but they tend to resist due to which breaking of mountains occurs.
● Water: - Water is another factor that helps in soil formation. Water fills up the cracks developed due to the heating and cooling of rocks and at causes the cracks to widen up more. Also, water takes away the smaller rocks and causes them to grind over one another ultimately causing them to break.
● Wind: - wind also works the same way by taking away the sand from one place to another.
● Living organism: - Some living organisms like lichens are the pioneer community i.e. they colonize the rocks first as the first living organism and they secrete certain acids when they grow on these rocks. Due to this secretion rocks becomes weak and break down easily. Roots of bigger trees can penetrate these rocks and can help in their breakdown. Along with them, other microorganisms and mosses help in the weathering of rocks.
While polythene doesn’t play any role during this process.