Explain the Formation of sedimentary rocks?

Lithification refers to the processes by which loose sediments are consolidated into new rock material. One of the most common forms of lithification is called compaction. As the weight of accumulating sediments increases through time, the force of all the layers above compresses lower layers into new rock material. This occurs in the oceans and on land; anywhere there is layering of sediment will cause lower layers to be compressed from the force of gravity. Cementation is a chemical process by which minerals suspended in water crystallize out into new rock material. This chemical sedimentation is best exemplified by the formation of limestone from organic debris on the oceans' floors.

The Law of Original Horizontality refers to the building up of sedimentary layers over time. Since gravity pulls materials straight down, the formation of sedimentary beds of new rock always occurs in a perfectly horizontal fashion. The importance of this law becomes evident later when evaluating warped and uplifted sedimentary layers. In knowing that the sedimentary layers of rock were all once lying flat, scientists and explorers can better estimate the original age and arrangement of rock formations and mountains with sedimentary layers. Another important rule when studying sedimentary rock formations is that the lower down the layer, the older it is. This is true because as the layer was built up, successive layers of sediment were deposited on top of previous layers.

Finding fossils is best done in sedimentary rock formations. Organisms become trapped in mud or sediment, then become buried and mineralized into the rock layers. Knowing the age of the rock layers will reveal the age of the fossilized organisms, and vise-versa, as knowing the fossil ages can give clues as to the age of the unknown rocks