• Three types of rocks-(1) Igneous (2) Sedimentary and (3) Metamorphic.
  1. Igneous: The rocks which are formed by the cooling of molten matter (Magma or lava) which comes outer from the interior of the earth.
  2. Sedimentary: The rocks which have been formed by the layers of beds (strata) of the material deposited by wind, glacier, running water or the sea.
  3. Metamorphic: The Sedimentary or igneous rocks which have changed their form in course of time due to intense heat and pressure in the interior of the earth and known as metamorphic rocks, e.g., marble, slate etc.
  • Weathering
  • It implies breaking up and decay of rocks by the action of the sun, rain, wind, water etc.
  • Denudation
  • It implies the wearing down of rocks or surface. It includes two processes-(1) the breaking of rocks material (2) the carrying away of that material, thereby laying the rocks base for further attack.
  • Denuding factors: (1) Wind (2) Water (3) Temperature (4) Glacier (5) Sea (6) Regelation (7) Animals (8) Gravity (9) Man etc.
  • Erosion
  • When the uppermost surface of the earth is worn out by the action of water, wind, storms; it is called soil erosion.