Sedimentary rocks are types of rock that are formed by the deposition and cementation of that material at the Earth's surface and within loads of water. Sedimentation is the name for processes that cause mineral and/or organic particles to settle in place.
The particles that form a sedimentary rock by accumulating are called sediment. Before being deposited, the sediment was formed by weathering and erosion from the source area, and then transported to the place of deposition by water, wind, ice, mass movement or glaciers, which are called agents of denudation. Sedimentation may also occur as minerals precipitate from water solution or shells of aquatic creatures settle out of suspension. The sedimentary rock cover of the Earth's crust. Sedimentary rocks are only a thin veneer over a crust consisting mainly igneous and metamorphic rocks. sedimentary rocks are deposited in layers as strata, forming a structure called bedding. The different types of sedimentary rocks are inorganic (classtic) sedimentary rocks, chemical (crystal) sedimentary rocks, and organic (bioclastic) sedimentary rocks.
Clastic Sedimentary Rocks
Inorganic Sedimentary Rocks
Organic Sedimentary Rocks
The layers are deposited in many environments including oceans, rivers and deserts. These layers of sand and mud are later buried. The weight of overlying layers compresses the mud and sand to form solid rock. Because sedimentary rocks begin to form at the Earth's surface
Igenous Rocks
Igneous rock is formed through the cooling and solidification of magma or lava. The magma can be derived from partial melts of existing rocks in either a planet's mantle or crust. Typically, the melting is caused by one or more of three processes: an increase in temperature, a decrease in pressure, or a change in composition. Solidification into rock occurs either below the surface as intrusive rocks or on the surface as extrusive rocks. Igneous rock may form with crystallization to form granular, crystalline rocks, or without crystallization to form natural glasses.
Intrusive Rocks
Intrusive igneous rocks are formed from magma that cools and solidifies within the crust of a planet, surrounded by pre-existing rock (called country rock); the magma cools slowly and, as a result, these rocks are coarse-grained. The mineral grains in such rocks can generally be identified with the naked eye. Intrusive rocks can also be classified according to the shape and size of the intrusive body and its relation to the other formations into which it intrudes. Typical intrusive formations are batholiths, stocks, laccoliths, sills and dikes. When the magma solidifies within the earth's crust, it cools slowly forming coarse textured rocks, such as granite, gabbro, or diorite.
Extrusive
Extrusive igneous rocks, also known as volcanic rocks, are formed at the crust's surface as a result of the partial melting of rocks within the mantle and crust. Extrusive igneous rocks cool and solidify quicker than intrusive igneous rocks. They are formed by the cooling of molten magma on the earth's surface. The magma, which is brought to the surface through fissures or volcanic eruptions, solidifies at a faster rate. Hence such rocks are smooth, crystalline and fine-grained.
Metamorphic Rocks
A metamorphic rock is a result of a transformation of a pre-existing rock. The original rock is subjected to very high heat and pressure, which cause obvious physical and/or chemical changes.Fossils can sometimes be found in it but they are often squashed.Metamorphic rock is formed under extreme pressure combined with heat over time.Metamorphic rocks make up a large part of the Earth's crust and form 12% of the Earth's current land surface.They are classified by texture and by chemical and mineral assemblage . They may be formed simply by being deep beneath the Earth's surface, subjected to high temperatures and the great pressure of the rock layers above it. They are also formed when rock is heated up by the intrusion of hot molten rock,magma, from the Earth's interior. The study of metamorphic rocks provides information about the temperatures and pressures that occur at great depths within the Earth's crust.
Marble-Marble is a metamorphic rock that forms when limestone is subjected to the heat and pressure of metamorphism. It is composed primarily of the mineral calcite and usually contains other minerals, such as clay minerals.Under the conditions of metamorphism, the calcite in the limestone recrystallizes to form a rock that is made of interlocking calcite crystals.
Gneiss-Gneiss is a high grade metamorphic rock,so that it has been featured to higher temperatures and pressures than schist. It is formed by the metamorphosis of granite, or sedimentary rock. Gneiss displays represents alternating layers made of different minerals.
Slate-Slate is a fine-grained, metamorphic rock that is created by the alteration of shale by low-grade metamorphism. It is popular for a use towards variety of uses such as roofing, flooring, and flagging because of its attractive appearance.Slate is composed mainly of micas, depending upon the metamorphism to which it has been opposed to. The original clay minerals in shale alter to micas with increasing levels of heat and pressure. Slate can also contain quartz and amounts of feldspar, calcite, pyrite, and other minerals.