seDIMENTARY ROCK
Sedimentary rock is another one of the three types of rocks. It can form from once living organisms, (they don't have to be). Sedimentary rocks forms when erosion carries sediment. Then, deposition occours, where the sediment settles. Compaction then presses the sediments together over millions of years. Finally, cementation "glues" the particles of sediment together. There are three different types of Sedimentary rocks, CLASTIC, ORGANIC, and CHEMICAL. All three types are formed differently.