Organic sedimentary rocks are sedimentary rocks formed from the remains of organisms. The three types of organic sedimentary rock are limestone, chert and coal. Both limestone and chert are formed largely from the hard structures of organisms, while coal is formed from dead plants after a long period of exposure to the correct environmental conditions.Know More
Bony fish, corals and certain planktonic algae form calcium-based structures that break down and settle to the ocean floor after their deaths. These build up under time and pressure, eventually solidifying into a solid mass known as limestone. Limestone is easily dissolved by acidic substances, even including rainwater, because of its calcium content. Marble is a metamorphic rock made from limestone exposed to extreme temperatures and pressures.
Another group of photosynthetic plankton, known as diatoms, as well as sponges create structures from silica. The sediments from diatoms are the source of diatomaceous earth, but when not gathered for this purpose time and pressure cause the formation of chert.
Coal is the only type of organic sedimentary rock that is not formed primarily in oceans. Instead, it form in shallow waters, particularly swamps, where plant debris is buried by sediment and exposed to various chemical processes, purifying the carbon component of the plants.Learn more about Geology
Sedimentary rocks are made of minerals and debris that have been weathered or eroded from rocks over long stretches of time. This sediment can be laid down by water, by the movement of earth or glaciers, by evaporation or by biological processes.Full Answer >
Sedimentary rocks come from the fragments of pre-existing rocks called sediments. There are three types of sedimentary rocks, each coming from different kinds of sediments. Clastic sedimentary rocks are created from the broken pieces of other rocks, while chemical sedimentary rocks form from mineral crystals like halite and gypsum.Full Answer >
Sedimentary rocks are rocks made by sediment that has accumulated over millions of years. This sediment can accumulate on the surface of the Earth or under water. Sedimentary rocks tend to resemble the sediment that created them, so they are usually gray or brown.Full Answer >
Sedimentary rocks are primarily characterized by lithification. Lithification occurs when sediment has been deposited and accumulates at the earth's surface or in bodies of water to form a rock over time. Subgroups of sedimentary rocks are defined by their specific formation.Full Answer >