With the earth coming into existence, the powers of denudation started on it. In this, rocks break down and get accumulated at the same place or elsewhere through weathering and erosion. The rocks formed by the accumulation of layers over the layers on the fossils of living – organisms, vegetation and rocks – flour obtained from different rocks, came to be known as Sedimentary Rocks. These rocks are formed by many types of substances and sediments. Many processes take place in their formation.