The rock cycle is a fundamental concept in geology that describes the dynamic transitions through geologic time among the three main rock types: sedimentary, metamorphic, and igneous. As the diagram to the right illustrates, each type of rock is altered or destroyed when it is forced out of its equilibrium conditions. An igneous rock such as basalt may break down and dissolve when exposed to the atmosphere, or melt as it is subducted under a continent. Due to the driving forces of the rock cycle, plate tectonics and the water cycle, rocks do not remain in equilibrium and are forced to change as they encounter new environments. The rock cycle is an illustration that explains how the 3 rock types are related to each other and how processes change from one type to another over time. This article includes a list of works cited but its sources remain unclear because it lacks in-text citations. ... The table and timeline of geologic periods presented here is in accordance with the dates and nomenclature proposed by the International Commission on Stratigraphy. ... The rocky side of a mountain creek near Orosí, Costa Rica. ... Two types of sedimentary rock: limey shale overlaid by limestone. ... Quartzite, a form of metamorphic rock, from the Museum of Geology at University of Tartu collection. ... Igneous rocks are formed when molten rock (magma) cools and solidifies, with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. ... Basalt Basalt (IPA: ) is a common gray to black extrusive volcanic rock. ... Layers of Atmosphere - not to scale (NOAA)[3] Earths atmosphere is a layer of gases surrounding the planet Earth and retained by the Earths gravity. ... The Juan de Fuca plate sinks below the North America plate at the Cascadia subduction zone. ... Animated, colour-coded map showing the various continents. ... The tectonic plates of the world were mapped in the second half of the 20th century. ... The movement of water around, over, and through the Earth is called the water cycle. ...

A diagram of the rock cycle.

Image File history File links Download high resolution version (960x718, 96 KB)Diagram describing the rock cycle, from [1] File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links Download high resolution version (960x718, 96 KB)Diagram describing the rock cycle, from [1] File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...

Historical development

The original concept of the rock cycle is usually attributed to James Hutton, the eighteenth century father of geology. The rock cycle was a part of Hutton's uniformitarianism and his famous quote: no vestige of a beginning, and no prospect of an end, applied in particular to the rock cycle and the envisioned cyclical nature of geologic processes. This concept of a repetitive non-evolutionary rock cycle remained dominant until the plate tectonics revolution of the 1960s. With the developing understanding of the driving engine of plate tectonics, the rock cycle changed from endlessly repetitive to a gradually evolving process. The Wilson cycle (a plate tectonics based rock cycle) was developed by J. Tuzo Wilson during the 1960s and 70s. this dude has a HUGE nose James Hutton, painted by Abner Lowe. ... Uniformitarianism has had two separate meanings, both more prevalent in 19th-century discourse: Within religious philosophy, Uniformitarianism (with a capital U) is the belief that the Universe has existed as it is now for an infinite time and will continue to exist for ever. ... 1960 (MCMLX) was a leap year starting on Friday (the link is to a full 1960 calendar). ... The tectonic plates of the world were mapped in the second half of the 20th century. ... The supercontinent cycle describes the quasi-periodic aggregration and dispersal of Earths continental crust. ... John Tuzo Wilson (October 24, 1908-April 15, 1993) was a Canadian geophysicist and geologist who achieved worldwide acclaim for his theory of plate tectonics, the assumption that the Earths crust is comprised of plates floating on magma. ... Centuries: 1st century BC - 1st century - 2nd century Decades: 20s - 30s - 40s - 50s - 60s - 70s - 80s - 90s - 100s - 110s - 120s 70 71 72 73 74 75 76 77 78 79 Note: Sometimes the 70s is used as shorthand for the 1970s, the 1870s, or other such decades in other centuries...

The cycle

Rock cycle - USGS

Image File history File links Rock cycle - USGS http://3dparks. ... Image File history File links Rock cycle - USGS http://3dparks. ...

Transition to igneous

When rocks are pushed deep under the Earth's surface, they may melt into magma. If the conditions no longer exist for the magma to stay in its liquid state, it will cool and solidify into an igneous rock. A rock that cools within the Earth is called intrusive or plutonic and will cool very slowly, producing a coarse-grained texture. As a result of volcanic activity, magma may cool very rapidly while being exposed to the atmosphere and are called extrusive or volcanic rocks. These rocks are fine-grained and sometimes cool so rapidly that no crystals can form and result in a natural glass, such as obsidian. Any of the three main types of rocks can melt into magma and cool into igneous rocks. Adjectives: Terrestrial, Terran, Telluric, Tellurian, Earthly Atmosphere Surface pressure: 101. ... Magma is molten rock located beneath the surface of the Earth (or any other terrestrial planet), and which often collects in a magma chamber. ... Pluton redirects here. ... This article is about volcanoes in geology. ... Layers of Atmosphere - not to scale (NOAA)[3] Earths atmosphere is a layer of gases surrounding the planet Earth and retained by the Earths gravity. ... Extrusive refers to the mode of igneous volcanic rock formation in which hot magma from inside the Earth flows out (extrudes) onto the surface as lava or explodes violently into the atmosphere to fall back as pyroclastics or tuff. ... Glass can be made transparent and flat, or into other shapes and colors as shown in this sphere from the Verrerie of Brehat in Brittany. ... Obsidian from Lake County, Oregon Counterclockwise from top: obsidian, pumice and rhyolite (light color) Obsidian is a rock which is a type of naturally occurring glass, produced by volcanoes (igneous origin) when a felsic lava cools rapidly and freezes without sufficient time for crystal growth (see glass transition temperature). ...

Post-volcanic changes

Rock masses of large shaped penis rocks have been found in igneous origin have no sooner consolidated than they begin to change. The gases with which the magma is charged are slowly dissipated, lava flows often remain hot and steaming for many years. These gases attack the components of the rock and deposit new minerals in cavities and fissures. The zeolites are largely of this origin. Even before these "post-volcanic" processes have ceased, atmospheric decomposition or weathering begins as the mineral components of volcanic and igneous rocks are not stable under surface atmospheric conditions. Rain, frost, carbonic acid, oxygen and other agents operate continuously, and do not cease until the whole mass has crumbled down and most of its ingredients have been resolved into new products or carried away in aqueous solution. In the classification of rocks these secondary changes are generally considered unessential: rocks are classified and described as if they were ideally fresh, though this is rarely the case in nature. Zeolite The micro-porous molecular structure of a zeolite, ZSM-5 Zeolites (Greek, zein, to boil; lithos, a stone) are minerals that have a micro-porous structure. ... Weathering is the process of breaking down rocks, soils and their minerals through direct contact with the atmosphere. ... Minerals are natural compounds formed through geological processes. ... Carbonic acid (ancient name acid of air or aerial acid) has the formula H2CO3. ...

Secondary changes

Epigenitic change (secondary processes) may be arranged under a number of headings, each of which is typical of a group of rocks or rock-forming minerals, though usually more than one of these alterations will be found in progress in the same rock. Silicification, the replacement of the minerals by crystalline or crypto-crystalline silica, is most common in felsic rocks, such as rhyolite, but is also found in serpentine, etc. Kaolinization is the decomposition of the feldspars, which are the most common minerals in igneous rocks, into kaolin (along with quartz and other clay minerals); it is best shown by granites and syenites. Serpentinization is the alteration of olivine to serpentine (with magnetite); it is typical of peridotites, but occurs in most of the mafic rocks. In uralitization secondary hornblende replaces augite; this occurs very generally in diabases; chloritization is the alteration of augite (biotite or hornblende) to chlorite, and is seen in many diabases, diorites and greenstones. Epidotization occurs also in rocks of this group, and consists in the development of epidote from biotite, hornblende, augite or plagioclase feldspar. Felsic is a term used in geology to refer to silicate minerals, magmas, and rocks which are enriched in the lighter elements such as silica, oxygen, aluminium, sodium, and potassium. ... Rhyolite This page is about a volcanic rock. ... This article does not cite any references or sources. ... Kaolin Kaolinite (Aluminium Silicate Hydroxide) Kaolinite is a mineral with the chemical composition Al2Si2O5(OH)4. ... Clay minerals are hydrous aluminium silicates, sometimes with minor amounts of iron, magnesium and other cations. ... Close-up of granite from Yosemite National Park, valley of the Merced River Quarrying granite for the Mormon Temple, Utah Territory. ... Syenite leucocratic variety of nepheline syenite from Sweden (särnaite). ... Serpentinization is a geological metamorphic process involving heat and water in which low-silica mafic and ultramafic rocks are oxidized and hydrolyzed with water into serpentinite. ... The mineral olivine (also called chrysolite and, when gem-quality, peridot) is a magnesium iron silicate with the formula (Mg,Fe)2SiO4. ... Serpentine Serpentine is a group of common rock-forming hydrous magnesium iron phyllosilicate ((Mg, Fe)3Si2O5(OH)4) minerals; it may contain minor amounts of other elements including chromium, manganese, cobalt and nickel. ... // Headline text Magnetite is a ferrimagnetic mineral form of iron(II,III) oxide, with chemical formula Fe3O4, one of several iron oxides and a member of the spinel group. ... Peridotite xenolith from San Carlos, southwestern United States. ... In geology, mafic minerals and rocks are silicate minerals, magmas, and volcanic and intrusive igneous rocks that have relatively high concentrations of the heavier elements. ... Amphibolite Amphibolite (IPA: ) is the name given to a rock consisting mainly of hornblende amphibole, the use of the term being restricted, however, to metamorphic rocks. ... Amphibole (Hornblende) Hornblende is a complex inosilicate series of minerals. ... Augite is a single chain inosilicate mineral described chemically as (Ca,Mg,Fe)SiO3 or calcium magnesium iron silicate. ... It has been suggested that this article or section be merged with Dolerite. ... Chlorite is a group of phyllosilicate minerals often classified as clays. ... Categories: Mineral stubs | Igneous rocks ... New Zealand greenstone is formed by the metamorphism of basalt. ... Epidosite is a highly altered epidote and quartz bearing rock. ... Epidote from Slovakia Epidote is a calcium aluminium iron sorosilicate mineral, Ca2(Al, Fe)3(SiO4)3(OH), crystallizing in the monoclinic system. ...

Transition to metamorphic

This diamond is a mineral from within an igneous or metamorphic rock that formed at high temperature and pressure.

Rocks exposed to high temperatures and/or pressures can be changed physically or chemically to form a different rock, called metamorphic. Regional metamorphism refers to the effects on large masses of rocks over a wide area, typically associated with mountain building events within orogenic belts. These rocks commonly exhibit distinct bands of differing mineralogy and colors, called foliation. Another main type of metamorphism is caused when a body of rock comes into contact with an igneous intrusion that heats up this surrounding country rock. This contact metamorphism results in a rock that is altered and re-crystallized by the extreme heat of the magma and/or by the addition of fluids from the magma that add chemicals to the surrounding rock (metasomatism). Any pre-existing type of rock can be modified by the processes of metamorphism. Wikipedia does not have an article with this exact name. ... Wikipedia does not have an article with this exact name. ... This article is about the gemstone. ... // Orogeny (Greek for mountain generating) is the process of mountain building, and may be studied as a tectonic structural event, as a geographical event and a chronological event, in that orogenic events cause distinctive structural phenomena and related tectonic activity, affect certain regions of rocks and crust and happen within... Foliation is any penetrative planar fabric present in rocks. ... Metasomatism is a geologic process where metamorphism causes an alteration in a mineral or rock mass that involves a chemical change of the substance with the addition of material, as when chrysolite (olivine) is converted to serpentine basically by the addition of water. ...

Transition to sedimentary

Rocks exposed to the atmosphere are variably unstable and subject to the processes of weathering and erosion. Weathering and erosion breaks the original rock down into smaller fragments and carries away dissolved material. This fragmented material accumulates and is buried by additional material. While an individual grain of sand is still a member of the class of rock it was formed from, a rock made up of such grains fused together is sedimentary. Sedimentary rocks can be formed from the lithification of these buried smaller fragments (clastic sedimentary rock), the accumulation and lithification of material generated by living organisms (biogenic sedimentary rock - fossils), or lithification of chemically precipitated material from a mineral bearing solution due to evaporation (precipitate sedimentary rock). Clastic rocks can be formed from fragments broken apart from larger rocks of any type, due to processes such as erosion or from organic material, like plant remains. Biogenic and precipitate rocks form from the deposition of minerals from chemicals dissolved from all other rock types. Layers of Atmosphere - not to scale (NOAA)[3] Earths atmosphere is a layer of gases surrounding the planet Earth and retained by the Earths gravity. ... Weathering is the process of breaking down rocks, soils and their minerals through direct contact with the atmosphere. ... Severe soil erosion in a wheat field near Washington State University, USA. For erosion as an operation of Mathematical morphology, see Erosion (morphology) Erosion is displacement of solids (soil, mud, rock and other particles) by the agents of ocean currents, wind, water, or ice by downward or down-slope movement... Lithification (from the Greek word lithos meaning rock and the Latin-derived suffix -ific) is the process whereby sediments compact under pressure, expel connate fluids, and gradually become solid rock. ... In geology, the term clastic refers to sediments formed from fragments of pre-existing rock. ... This article does not cite any references or sources. ... A biogenic substance is a substance produced by natural processes. ... FOSSIL is a standard for allowing serial communication for telecommunications programs under DOS. FOSSIL is an acronym for Fido Opus Seadog Standard Interface Layer. ... Evaporation is the process whereby atoms or molecules in a liquid state (or solid state if the substance sublimes) gain sufficient energy to enter the gaseous state. ... Severe soil erosion in a wheat field near Washington State University, USA. For erosion as an operation of Mathematical morphology, see Erosion (morphology) Erosion is displacement of solids (soil, mud, rock and other particles) by the agents of ocean currents, wind, water, or ice by downward or down-slope movement... Minerals are natural compounds formed through geological processes. ...

Forces that drive the rock cycle

Plate tectonics

Main article: Plate Tectonics

In 1967, J. Tuzo Wilson published an article in Nature describing the repeated opening and closing of ocean basins, in particular focusing on the current Atlantic Ocean area. This concept, a part of the plate tectonics revolution, became known as the Wilson cycle. The Wilson cycle has had profound effects on the modern interpretation of the rock cycle as Plate tectonics became recognized as the driving force for the rock cycle. The tectonic plates of the world were mapped in the second half of the 20th century. ...

Spreading ridges

The start of the cycle can be placed at the mid-ocean divergent boundaries where new magma is produced by mantle upwelling and a shallow melting zone. This new or juvenile basaltic magma is the first phase of the igneous portion of the cycle. It should be noted that the least dense magma phases tend to be favored in eruptions. As the ridge spreads and the new rock is carried away from the ridge, the interaction of heated circulating seawater through crevices starts the initial retrograde metamorphism of the new rock. A mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, formed by plate tectonics. ... Magma is molten rock located beneath the surface of the Earth (or any other terrestrial planet), and which often collects in a magma chamber. ... Earth cutaway from core to exosphere. ... Basalt Basalt (IPA: ) is a common gray to black extrusive volcanic rock. ... Annual mean sea surface salinity for the World Ocean. ...

Subduction zones

The Juan de Fuca plate sinks below the North America plate at the Cascadia subduction zone.

Main article: Subduction

The new basaltic oceanic crust eventually meets a subduction zone as it moves away from the spreading ridge. As this crust is pulled back into the mantle, the increasing pressure and temperature conditions cause a restructuring of the mineralogy of the rock, this metamorphism alters the rock to form eclogite. As the slab of basaltic crust and some included sediments are dragged deeper, water and other more volatile materials are driven off and rise into the overlying wedge of rock above the subduction zone which is at a lower pressure. The lower pressure, high temperature, and now volatile rich material in this wedge melts and the resulting buoyant magma rises through the overlying rock to produce island arc or continental margin volcanism. This volcanism includes more silicic lavas the further from the edge of the island arc or continental margin, indicating a deeper source and a more differentiated magma. USGS image of a subduction zone. ... USGS image of a subduction zone. ... Structure of the Cascadia subduction zone Area of the Cascadia subduction zone The Cascadia subduction zone is a very long sloping fault that stretches from northern Vancouver Island to northern California. ... The Juan de Fuca plate sinks below the North America plate at the Cascadia subduction zone. ... Age of oceanic crust Oceanic crust is the part of Earths lithosphere which underlies the ocean basins. ... The Juan de Fuca plate sinks below the North America plate at the Cascadia subduction zone. ... Eclogite is a coarse-grained, mafic-to-ultramafic grouping of metamorphic rocks of special interest on account of the variety of minerals they contain and their microscopic structures and geological relationships. ... The ability of a liquid to evaporate quickly and at relatively low temperatures. ... An island arc is a type of archipelago formed by plate tectonics as one oceanic tectonic plate subducts under another and produces magma. ... This article is about volcanoes in geology. ...

At times some of the metamorphosed downgoing slab may be thrust up or obducted onto the continental margin. These blocks of mantle peridotite and the metamorphic eclogites are exposed as ophiolite complexes. Obduction is the overthrusting of continental crust by oceanic crust or mantle rocks. ... Peridotite xenolith from San Carlos, southwestern United States. ... Eclogite is a coarse-grained, mafic-to-ultramafic grouping of metamorphic rocks of special interest on account of the variety of minerals they contain and their microscopic structures and geological relationships. ... Ophiolites are sections of oceanic lithosphere that have been uplifted or emplaced to be exposed within continental crustal rocks. ...

The newly erupted volcanic material is subject to rapid erosion depending on the climate conditions. These sediments accumulate within the basins on either side of an island arc. As the sediments become more deeply buried lithification begins and sedimentary rock results.

Continental collision

On the closing phase of the classic Wilson cycle, two continental or smaller terranes meet at a convergent zone. As the two masses of continental crust meet, neither can be subducted as they are both low density silicic rock. As the two masses meet, tremendous compressional forces distort and modify the rocks involved. The result is regional metamorphism within the interior of the ensuing orogeny or mountain building event. As the two masses are compressed, folded and faulted into a mountain range by the continental collision the whole suite of pre-existing igneous, volcanic, sedimentary and earlier metamorphic rock units are subjected to this new metamorphic event. The thickness of the Earths crust (km). ... // Orogeny (Greek for mountain generating) is the process of mountain building, and may be studied as a tectonic structural event, as a geographical event and a chronological event, in that orogenic events cause distinctive structural phenomena and related tectonic activity, affect certain regions of rocks and crust and happen within...

Accelerated erosion

The high mountain ranges produced by continental collisions are immediately subjected to the forces of erosion. Erosion wears down the mountains and massive piles of sediment are developed in adjacent ocean margins, shallow seas, and as continental deposits. As these sediment piles are buried deeper they become lithified into sedimentary rock. The metamorphic, igneous, and sedimentary rocks of the mountains become the new piles of sediments in the adjoining basins and eventually become sedimentary rock.

An evolving process

The plate tectonics rock cycle is an evolutionary process. Magma generation, both in the spreading ridge environment and within the wedge above a subduction zone, favors the eruption of the more silicic and volatile rich fraction of the crustal or upper mantle material. This lower density material tends to stay within the crust and not be subducted back into the mantle. The magmatic aspects of plate tectonics tends to gradual segregation within or between the mantle and crust. As magma forms, the initial melt is composed of the more silicic phases that have a lower melting point. This leads to partial melting and further segregation of the lithosphere. In addition the silicic continental crust is relatively buoyant and is not normally subducted back into the mantle. So over time the continental masses grow larger and larger.

The important role of water

Main article: Water cycle

The surface pattern on this pedestal rock is honeycomb weathering, caused by salt crystallization. This example is at Yehliu, Taiwan.

The presence of abundant water on Earth is of great importance for the rock cycle. Most obvious perhaps are the water driven processes of weathering and erosion. Water in the form of precipitation and acidic soil water and groundwater is quite effective at dissolving minerals and rocks, especially those igneous and metamorphic rocks and marine sedimentary rocks that are unstable under near surface and atmospheric conditions. The water carries away the ions dissolved in solution and the broken down fragments that are the products of weathering. Running water carries vast amounts of sediment in rivers back to the ocean and inland basins. The accumulated and buried sediments are converted back into rock. The movement of water around, over, and through the Earth is called the water cycle. ... Image File history File links File links The following pages link to this file: Weathering Rock cycle ... Image File history File links File links The following pages link to this file: Weathering Rock cycle ... The Queens Head, the most famous of the eroded shapes Yehliu (野柳) is a peninsula on the north coast of Taiwan, between Taipei and Keelung. ... This article describes water from a scientific and technical perspective. ... Weathering is the process of breaking down rocks, soils and their minerals through direct contact with the atmosphere. ... Severe soil erosion in a wheat field near Washington State University, USA. For erosion as an operation of Mathematical morphology, see Erosion (morphology) Erosion is displacement of solids (soil, mud, rock and other particles) by the agents of ocean currents, wind, water, or ice by downward or down-slope movement... Acidity redirects here. ... Loess field in Germany Surface-water-gley developed in glacial till, Northern Ireland Technically, Soil forms the pedosphere: the interface between the lithosphere (rocky part of the planet) and the biosphere, atmosphere, and hydrosphere. ... Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of geologic formations. ... An electrostatic potential map of the nitrate ion (NO3−). Areas coloured red are lower in energy than areas colored yellow An ion is an atom or group of atoms which have lost or gained one or more electrons, making them negatively or positively charged. ...

A less obvious role of water is in the metamorphism processes that occur in fresh seafloor volcanic rocks as seawater, sometimes heated, flows through the fractures and crevices in the rock These processes, illustrated by serpentinization, are an important part of the destruction of volcanic rock. A sample of serpentinite rock, partially made up of chrysotile Serpentinite is a rock comprised of one or more serpentine minerals. ...

The role of water and other volatiles in the melting of existing crustal rock in the wedge above a subduction zone is a most important part of the cycle. Along with water, the presence of carbon dioxide and other carbon compounds from abundant marine limestone within the sediments atop the downgoing slab is another source of melt inducing volatiles. This involves the carbon cycle as a part of the overall rock cycle. Carbon dioxide is a chemical compound composed of one carbon and two oxygen atoms. ... This article does not cite any references or sources. ... The carbon cycle is the biogeochemical cycle by which carbon is exchanged between the biosphere, geosphere, hydrosphere,and atmosphere of the Earth (other astronomical objects may have similar carbon cycles, but nothing is yet known about them). ...

References

Encyclopædia Britannica, the 11th edition The Encyclopædia Britannica Eleventh Edition (1910–1911) is perhaps the most famous edition of the Encyclopædia Britannica. ... The public domain comprises the body of all creative works and other knowledge—writing, artwork, music, science, inventions, and others—in which no person or organization has any proprietary interest. ...

External links

• The Six Fundamental Concepts about the Earth's Geology - NASA
• Wilson cycle - a detailed Plate Tectonics rock cycle
• The Rock Cycle Song
• Modelling the rock cycle with STELLA
• Wilson cycle
• A circular Wilson cycle?