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.Continue Reading
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
Fossil fuels are formed the gradual accumulation of organic remains on the sea floor. As the accumulation rate increases, the organic remains are subjected to heat and pressure, which leads to fossil-fuel formation.Full Answer >
Organic matter in soil is compacted by the weight of new soil, created by decaying matter, into an organic sediment layer called peat. Given enough time, this peat becomes overrun with minerals from underground water until it becomes one of many types of sedimentary rock, including shale and limestone.Full Answer >
Non-foliated metamorphic rocks are rocks that have been changed by heat and pressure into rocks with a non-layered or banded appearance. Some examples of non-foliated metamorphic rocks include quartzite, marble, amphibolite and hornfels.Full Answer >
Igneous rocks are often used for construction because of their durability. Igneous rocks can also be separated to access the various valuable metals and minerals inside them. Igneous rocks form as magma comes to or near the surface of the Earth; cooling and hardening because of its distance from the inner parts of the Earth where magma forms.Full Answer >