Answer 1

1. Climate: The climate in which Soil develops is the most important factor. It is responsible for the following:
   (a) Weathering: Extremes of temperature, freezing and thawing of ice break down rocks and favour Soil formation.
   (b) Vegetation: The growth and decay of vegetation determines the humus content of the Soil. Roots of plants penetrate the Soil and make it porous.
   (c) Bio-chemical processes taking place in Soil: Bacteria and fungi cause the decay of plants and animal remains. Some transform the atmospheric nitrogen into Soil nitrogen.
2. The Parent rock: The physical and chemical composition of the parent rock determines the relative proportion of different minerals in the Soil layers.
3. The Topography: The slope of the land surface is an important factor in the formation of Soil layer.
   (a) Hills and slopes: Steep slopes usually have a thin Soil layer because weathered particles are easily carried downslope by running water and wind.
   (b) Plains and Valleys: On flat plains and in valleys, thick fertile Soils are developed.