Weathering forces keep on breaking the rocks to convert them into soil. The heat from the sun, rain, frost and wind physically break the rocks. Rocks expand because of heat from the sun and contract when they cool down during night. Continuous contraction and expansion make the rocks weaker and they start to break down. Force of the falling rain increases the rate of breakdown of rocks. The rainwater also weathers down the rocks. Water which gets collected in the fissures in the rock becomes frozen due to frost. We know that volume of water increases on freezing. Increased volume of ice further widens the fissures in rocks. When dust particles hit the rocks because of wind, they work like sandpaper and weather the rock. This is a slow process but its whole effect becomes apparent after thousands of years. Weathering by wind is considered as the reason for lack of mountains in deserts. Mountains which existed in desert changed into sand due to weathering. Many chemical processes keep on happening in nature, e.g. oxidation, carbonation, coalescing of water molecules, dissolution, etc. These processes also facilitate weathering of rocks by making them weaker. Biological forces like plants, animals, microbes and humans also play important role in weathering of rocks. Roots of plants penetrate the rocks and break the rocks when the roots grow. Many animals break the rocks by making holes. Man has proved to be the biggest enemy of rocks. Weathering potential of man is greatest because of machines and gunpowder. Living beings give off many chemicals in nature and such chemicals help in weathering of rocks.
