How is soil formed?

Soil formation in nature takes place by weathering of rocks by mechanical, chemical and biological methods.

• Physical Factors
  Wind: When the wind blows it erodes big rocks which rub with other rocks breaking into small pieces which are further carried by wind to form soil.
  Sun:  The heat of the sun causes expansion of the rocks due to heating during day time and it contracts at night. This expansion of the rocks causes cracks in the rocks, which break slowly to form soil.
  Water: When it rains the force of rainwater erodes the rock which breaks to form soil.
• Chemical Factor
  Water: Water when reacts with carbonates and phosphates present in the rock, it forms soluble compounds which make the rock hollow from inside.
• Biological factor:The living organism also helps in the formation of soil. the lichens that grow on moist rock surface release certain substances that cause the rock surface to powder down and form a thin layer of soil. Other small plants like moss are able to grow in this new surface.