The breaking of rocks near the Earth's surface by various physical, chemical and biological processes over a long period of time leads to the formation of soil.
Factors that help in the formation of soil are:
(i) Sun: Sun heats up rocks during the day causing them to expand. At night these rocks cool down and contract. This unequal expansion and contraction causes cracks in the rocks.
(ii) Water: Water during rainfall after enter these cracks, may freeze and cause the crack to widen. Also, Flowing water wears away rocks over long periods of time breaking it into smaller and smaller particles.
(iii) Wind: Strong winds erode rocks down, which rub with each other.
(iv) Living Organisms: Lichen growing on the surface of the rock, releases certain substances that cause the rock surface to powder down and form a thin layer of soil.