Examples of clastic and carbonate sedimentary rock layers at the Grand Canyon photo taken from South Kaibab Trail.
The study of ancient reefs requires a basic understanding of sedimentary rocks. Most sedimentary rocks are deposited under water as layers, which can also be called beds or strata. There are three basic types of sedimentary rocks. 1) Clastic sedimentary rocks form by the accumulation of sediment particles eroded from older rocks, and they represent mud, sand or gravel that has hardened into rock. 2) Carbonate sedimentary rocks, including limestone and dolostone, form when organic activity or inorganic precipitation extracts carbonate from seawater to form a sediment composed of calcium carbonate or calcium-magnesium carbonate. 3) Chemical sedimentary rocks form as minerals dissolved in water precipitate out of solution. When salt water evaporates Halite (salt) and gypsum are deposited.