Sedimentary

rock is that which has formed from sediment deposited by water or air. Being the most visible portion of the crust, sedimentary rock collects as a thin layer at the surface of the Earth. This type of rock is generally composed of dust, sand, or mud. Depending on its composition, sedimentary rock can either be clastic, organic, or chemical. Both limestone and sandstone are common building stones that are sedimentary.