Explain the formation of residual soil.

Pedogenesis: Basically, the process of soil formation is known as Pedogenesis.  And the formation of soil is cyclic, which is known as 'geological cycle'.

Almost all the soils are formed by the disintegration or weathering of rocks. The weathering can be either physical weathering or chemical weathering. If the soil stays at the place of its formation even after weathering, is known as residual soil or sedentary soil. In residual soils, the weathered sediments remain over the parent rock.