Sedimentary Rocks are formed by sediment and or chemical reactions. Sediment is loose material such as bits of rocks ,mineral,plants and animals. Water wind and ice can move sediment to places where it settles in like ocean floors, lakes, and rivers. Whenever this happens a new layer of sediment settles. Sedimentary rocks are usually formed in oceans and lakes where larger and heavier fragments settle first. Each layer of sediment is squeezed together by the weight above it.