Geology 12207 223381108 2008-07-03T20:50:34Z Autodidactyl 3483605 [[WP:UNDO|Undid]] revision 223353106 by [[Special:Contributions/92.19.51.17|92.19.51.17]] ([[User talk:92.19.51.17|talk]]) {{for|the scientific journal|Geology (journal)}} [[Image:World geologic provinces.jpg|thumb|300px|World geologic provinces '''[[Oceanic crust]]''' {{legend|#cde|0-20 Ma}} {{legend|#abc|20-65 Ma}} {{legend|#89a|>65 Ma}} '''[[Geologic province]]s''' {{legend|#f96|[[Shield (geology)|Shield]]}} {{legend|#f9c|[[Continental platform|Platform]]}} {{legend|#9fc|[[Orogeny|Orogen]]}} {{legend|#9cf|[[Basin (geology)|Basin]]}} {{legend|#969|Large [[igneous rock|igneous]] province}} {{legend|#ff9|Extended [[crust (geology)|crust]]|border=#dc8}} ]] {{WVS}} '''Geology''' (from [[Greek language|Greek]]: γη, ''gê'', "earth"; and λόγος, ''[[logos]]'', "speech" lit. to talk about the earth) is the [[science]] and study of the solid matter that constitutes the [[Earth]]. Encompassing such things as rocks, soil, and gemstones, geology studies the composition, structure, physical properties, history, and the processes that shape Earth's components. It is one of the [[Earth science]]s. [[Geologist]]s have established the [[age of the Earth]] at about 4.6 billion (4.6x10<sup>9</sup>) years, and have determined that the Earth's [[lithosphere]], which includes the [[Crust (geology)|crust]], is fragmented into [[tectonic plate]]s that move over a [[rheid|rheic]] upper [[Mantle (geology)|mantle]] ([[asthenosphere]]) via processes that are collectively referred to as [[plate tectonics]]. Geologists help locate and manage the Earth's [[natural resource]]s, such as [[petroleum]] and [[coal]], as well as [[metals]] such as [[iron]], [[copper]], and [[uranium]]. Additional economic interests include [[gemstone]]s and many minerals such as [[asbestos]], [[perlite]], [[mica]], [[phosphates]], [[zeolites]], [[clay]], [[pumice]], [[quartz]], and [[silica]], as well as elements such as [[sulfur]], [[chlorine]], and [[helium]]. Geology is also of great importance in the applied fields of [[civil engineering]], [[soil mechanics]], [[hydrology]], [[environmental engineering]] and [[geohazard]]s. [[Planetary geology]] (sometimes known as Astrogeology) refers to the application of geologic principles to other bodies of the solar system. Specialised terms such as ''selenology'' (studies of the [[moon]]), ''areology'' (of [[Mars]]), etc., are also in use. Colloquially, ''geology'' is most often used with another noun when indicating extra-Earth bodies (e.g. "the geology of Mars"). The word "geology" was first used by [[Jean-André Deluc]] in the year 1778 and introduced as a fixed term by [[Horace-Bénédict de Saussure]] in the year 1779. The science was not included in ''[[Encyclopædia Britannica]]'s'' third edition completed in 1797, but had a lengthy entry in the fourth edition completed by 1809.<ref>{{cite book | last = Winchester | first = Simon | authorlink = Simon Winchester | title = [[The Map that Changed the World]] | publisher = HarperCollins Publishers | date = 2001 | pages = 25 }} ISBN 0-06-093180-9 </ref> An older meaning of the word was first used by [[Richard Aungerville|Richard de Bury]] to distinguish between earthly and [[Theology|theological]] jurisprudence. ==History== {{main|History of geology}} [[Image:Insects in baltic amber.jpg|thumb|right|200px|A [[mosquito]] and a [[fly]] in this [[Baltic Sea|Baltic]] amber necklace are between 40 and 60 million years old]] The work ''[[Peri Lithon]]'' (''On Stones'') by [[Theophrastus]] (372-287 BC), a student of [[Aristotle]], remained authoritative for millennia. Its interpretation of [[fossils]] was not overturned until after the [[Scientific Revolution]]. ''[[Peri Lithon]]'' was translated into [[Latin]] and some other foreign languages. Much later in the [[Ancient Rome|Roman]] period, [[Pliny the Elder]] produced a very extensive discussion of many more minerals and [[metal]]s then widely used for practical ends. He is among the first to correctly identify the origin of [[amber]] as a [[fossilized]] [[resin]] from pine trees by the observation of insects trapped within some pieces. He also laid the basis of [[crystallography]] by recognising the [[octahedral]] habit of [[diamond]]. Some modern scholars, such as [[Fielding H. Garrison]], are of the opinion that modern geology began in the [[Islamic Golden Age|medieval Islamic world]].<ref>[[Fielding H. Garrison]] wrote in the ''History of Medicine'': <br />{{quote|"The [[Saracen]]s themselves were the originators not only of [[algebra]], [[chemistry]], and geology, but of many of the so-called improvements or refinements of civilization, such as [[Street light|street lamps]], [[window]]-[[Paned window|panes]], [[firework]], [[string instrument|stringed instruments]], [[cultivation|cultivated]] [[fruit]]s, [[perfume]]s, [[spice]]s, etc."}}</ref> [[Abū al-Rayhān al-Bīrūnī|Abu al-Rayhan al-Biruni]] (973-1048 AD) was one of the earliest [[Islamic geography|Muslim geologists]], whose works included the earliest writings on the [[geology of India]], hypothesizing that the [[Indian subcontinent]] was once a [[sea]].<ref name=Salam>[[Abdus Salam]] (1984), "Islam and Science". In C. H. Lai (1987), ''Ideals and Realities: Selected Essays of Abdus Salam'', 2nd ed., World Scientific, Singapore, p. 179-213.</ref> [[Avicenna|Ibn Sina]] (Avicenna, 981 - 1037 C.E.), in particular, made significant contribution to natural sciences (which he called ''Attabieyat'') along with other natural philosophers such as [[Brethren of Purity|Ikhwan AI-Safa]] and many others. He wrote an encyclopaedic work entitled “''[[The Book of Healing|Kitab al-Shifa]]''” (the Book of Cure, Healing or Remedy from ignorance), in which Part 2, Section 5, contains his essay on Mineralogy and Meteorology, in six chapters: Formation of [[mountain]]s, The advantages of mountains in the formation of [[cloud]]s; Sources of [[water]]; Origin of [[earthquake]]s; Formation of [[mineral]]s; The diversity of earth’s [[terrain]]. These principles were later known in the [[Renaissance]] of [[Europe]] as the [[law of superposition]] of strata, the concept of [[catastrophism]], and the doctrine of [[Uniformitarianism (science)|uniformitarianism]]. These concepts were also embodied in the Theory of the Earth by [[James Hutton]] in the Eighteenth century C.E. Academics such as [[Stephen Toulmin|Toulmin]] and [[June Goodfield|Goodfield]] (1965), commented on Avicenna's contribution: "Around A.D. 1000, Avicenna was already suggesting a hypothesis about the origin of mountain ranges, which in the Christian world, would still have been considered quite radical eight hundred years later".<ref>Toulmin, S. and Goodfield, J. (1965), ’The Ancestry of science: The Discovery of Time’, Hutchinson & Co., London, p.64. Also see http://muslimheritage.com/topics/default.cfm?ArticleID=319 </ref> In [[China]], the [[polymath]] [[Shen Kua]] (1031-1095) formulated a hypothesis for the process of land formation: based on his observation of [[fossil]] [[animal shell|shells]] in a geological [[stratum]] in a mountain hundreds of miles from the ocean, he inferred that the land was formed by [[erosion]] of the [[mountain]]s and by [[Deposition (sediment)|deposition]] of [[silt]]. [[Georg Agricola]] (1494-1555), a physician, wrote the first systematic treatise about [[mining]] and [[smelting]] works, ''[[De re metallica]] libri XII'', with an appendix ''Buch von den Lebewesen unter Tage'' (Book of the Creatures Beneath the Earth). He covered subjects like [[wind energy]], [[hydropower|hydrodynamic power]], melting cookers, transport of [[ore]]s, extraction of [[sodium|soda]], [[sulfur]] and [[alum]], and administrative issues. The book was published in 1556. [[Nicolas Steno]] (1638-1686) is credited with the [[law of superposition]], the [[principle of original horizontality]], and the [[principle of lateral continuity]]: three defining principles of [[stratigraphy]]. Previous attempts at such statements met accusations of heresy from the Church.{{Fact|date=April 2007}} By the 1700s [[Jean-Étienne Guettard]] and [[Nicolas Desmarest]] hiked central France and recorded their observations on [[Geologic map|geological maps]]; Guettard recorded the first observation of the [[Volcano|volcanic]] origins of this part of France. [[William Smith (geologist)|William Smith]] (1769-1839) drew some of the first geological maps and began the process of ordering [[rock strata]] (layers) by examining the fossils contained in them. [[James Hutton]] is often viewed as the first modern geologist. In 1785 he presented a paper entitled ''Theory of the Earth'' to the [[Royal Society of Edinburgh]]. In his paper, he explained his theory that the Earth must be much older than had previously been supposed in order to allow enough time for mountains to be eroded and for [[sediment]]s to form new rocks at the bottom of the sea, which in turn were raised up to become dry land. Hutton published a two-volume version of his ideas in 1795 ([http://www.gutenberg.org/etext/12861 Vol. 1], [http://www.gutenberg.org/etext/14179 Vol. 2]). [[Image:Carl Spitzweg 025.jpg|thumb|left|''The geologist'', 19th century painting by [[Carl Spitzweg]].]] Followers of Hutton were known as ''[[Plutonism|Plutonists]]'' because they believed that some rocks were formed by [[vulcanism]] which is the deposition of lava from [[volcano]]es, as opposed to the ''[[Neptunism|Neptunists]]'', who believed that all rocks had settled out of a large ocean whose level gradually dropped over time. In 1811 [[Georges Cuvier]] and [[Alexandre Brongniart]] published their explanation of the antiquity of the Earth, inspired by Cuvier's discovery of fossil elephant bones in Paris. To prove this, they formulated the principle of [[Stratigraphy|stratigraphic]] succession of the layers of the earth. They were independently anticipated by [[William Smith (geologist)|William Smith's]] stratigraphic studies on [[England]] and [[Scotland]]. By 1827 [[Charles Lyell]]'s ''Principles of Geology'' reiterated Hutton's uniformitarianism, which influenced the thought of [[Charles Darwin]]. [[Sir Charles Lyell]] first published his famous book, ''Principles of Geology'', in 1830 and continued to publish new revisions until he died in 1875. He successfully promoted the doctrine of [[Uniformitarianism (science)|uniformitarianism]]. This theory states that slow geological processes have occurred throughout the [[History of Earth|Earth's history]] and are still occurring today. In contrast, [[catastrophism]] is the theory that Earth's features formed in single, catastrophic events and remained unchanged thereafter. Though Hutton believed in uniformitarianism, the idea was not widely accepted at the time. [[Image:Wegener.jpg|thumb|right|Plate tectonics - [[seafloor spreading]] and [[continental drift]] illustrated on relief globe of the [[Field Museum]] ]] 19th century geology revolved around the question of the [[Age of the Earth|Earth's exact age]]. Estimates varied from a few 100,000 to billions of years. The most significant advance in 20th century geology has been the development of the theory of [[plate tectonics]] in the 1960s. Plate tectonic theory arose out of two separate geological observations: [[seafloor spreading]] and [[continental drift]]. The theory revolutionized the [[Earth sciences]]. The theory of continental drift was proposed by [[Frank Bursley Taylor]] in 1908, expanded by [[Alfred Wegener]] in 1912 and by [[Arthur Holmes]], but wasn't broadly accepted until the late 1960s when the theory of plate tectonics was developed. ==Important principles of geology== There are a number of important principles in geology. Many of these involve the ability to provide the relative ages of strata or the manner in which they were formed. '''The principle of intrusive relationships''' concerns crosscutting [[Intrusion (geology)|intrusions]]. In geology, when an [[igneous rocks|igneous]] intrusion cuts across a formation of [[sedimentary rock]], it can be determined that the igneous intrusion is younger than the sedimentary rock. There are a number of different types of intrusions, including stocks, [[laccolith]]s, [[batholith]]s, [[Sill (geology)|sills]] and [[Dike (geology)|dikes]]. '''The [[principle of cross-cutting relationships]]''' pertains to the formation of [[Geologic fault|faults]] and the age of the sequences through which they cut. Faults are younger than the rocks they cut; accordingly, if a fault is found that penetrates some formations but not those on top of it, then the formations that were cut are older than the fault, and the ones that are not cut must be younger than the fault. Finding the key bed in these situations may help determine whether the fault is a [[normal fault]] or a [[thrust fault]]. '''The principle of inclusions and components''' states that, with sedimentary rocks, if inclusions (or ''[[Clastic rocks|clasts]]'') are found in a formation, then the inclusions must be older than the formation that contains them. For example, in sedimentary rocks, it is common for gravel from an older formation to be ripped up and included in a newer layer. A similar situation with igneous rocks occurs when [[xenolith]]s are found. These foreign bodies are picked up as [[magma]] or [[lava]] flows, and are incorporated, later to cool in the matrix. As a result, xenoliths are older than the rock which contains them. '''The [[Uniformitarianism (science)|principle of uniformitarianism]]''' states that the geologic processes observed in operation that modify the Earth's crust at present have worked in much the same way over geologic time. A fundamental principle of geology advanced by the 18th century Scottish physician and geologist [[James Hutton]], is that "the present is the key to the past." In Hutton's words: "the past history of our globe must be explained by what can be seen to be happening now." '''The [[principle of original horizontality]]''' states that the deposition of sediments occurs as essentially horizontal beds. Observation of modern marine and non-marine sediments in a wide variety of environments supports this generalization (although [[cross-bedding]] is inclined, the overall orientation of cross-bedded units is horizontal). '''The [[Law of superposition|principle of superposition]]''' states that a sedimentary rock layer in a tectonically undisturbed sequence is younger than the one beneath it and older than the one above it. Logically a younger layer cannot slip beneath a layer previously deposited. This principle allows sedimentary layers to be viewed as a form of vertical time line, a partial or complete record of the time elapsed from deposition of the lowest layer to deposition of the highest bed. '''The [[principle of faunal succession]]''' is based on the appearance of fossils in sedimentary rocks. As organisms exist at the same time period throughout the world, their presence or (sometimes) absence may be used to provide a relative age of the formations in which they are found. Based on principles laid out by [[William Smith (geologist)|William Smith]] almost a hundred years before the publication of [[Charles Darwin]]'s [[theory of evolution]], the principles of succession were developed independently of evolutionary thought. The principle becomes quite complex, however, given the uncertainties of fossilization, the localization of fossil types due to lateral changes in habitat ([[facies]] change in sedimentary strata), and that not all fossils may be found globally at the same time. ==Fields or related disciplines== {{FixHTML|beg}} [[Image:Syncline and anticline.svg|thumb|300px|An illustrated depiction of a [[syncline]] and [[anticline]] commonly studied in [[Structural geology]] and [[Geomorphology]].]] [[Image:Oceanic-continental convergence Fig21oceancont.svg|thumb|300px|Oceanic-continental convergence resulting in [[subduction]] and [[volcanic arc]]s illustrates one effect of [[plate tectonics]].]] {{FixHTML|end}} {{top|width=63%|width2=31%|bgcolor=#bFFFB0}} <!-- removing bgcolor gives transparent default ---> * [[Earth science]] * [[Economic geology]] ** [[Mining|Mining geology]] ** [[Petroleum geology]] * [[Engineering geology]] * [[Environmental geology]] * [[Geoarchaeology]] * [[Geochemistry]] ** [[Biogeochemistry]] ** [[Isotope geochemistry]] * [[Geochronology]] * [[Geodetics]] * [[Geography]] * [[Geological modelling]] * [[Geomicrobiology]] * [[Geomorphology]] * [[Geomythology]] * [[Geophysics]] * [[Glaciology]] * [[Historical geology]] * [[Hydrogeology]] or [[geohydrology]] {{mid|width=63%|width2=33%|bgcolor=#bFFFb0}} * [[Mineralogy]] * [[Oceanography]] ** [[Marine geology]] * [[Paleoclimatology]] * [[Paleontology]] ** [[Micropaleontology]] ** [[Palynology]] * [[Petrology]] * [[Petrophysics]] * [[Plate tectonics]] * [[Sedimentology]] * [[Seismology]] * [[Soil science]] ** [[Pedology (soil study)]] * [[Speleology]] * [[Stratigraphy]] ** [[Biostratigraphy]] ** [[Chronostratigraphy]] ** [[Lithostratigraphy]] * [[Structural geology]] * [[Volcanology]] {{bottom}} ==Regional geology== * [[Geology of the Alps]] * [[Geology of the Appalachians]] * [[Geology of the Himalaya]] ===By nations=== {{Top|width=64%}} <!-- width may be unnecessary here, but makes room for pics or diagrams if desired. --- Any multiple group of such should be "framed" using the Template:FixHTML as used in above section --- as different browser rendering ordering priorities can cause edge displacements in pages with adjacent --- block elements such as those hypothetical pics and this table ---> * [[Geology of Australia]] ** [[Geology of the Australian Capital Territory]] ** [[Geology of Victoria]] ** [[Yilgarn craton|Geology of the Yilgarn Craton]] * [[Geology of China]] ** [[Geology of Hong Kong]] * [[Geology of Europe]] ** [[Geology of the Netherlands]] ** [[Geology of Norway]] ** [[Geology of the United Kingdom]] *** [[Geology of England]] **** [[Geology of Dorset]] **** [[Geology of Hampshire]] **** [[Geology of Hertfordshire]] **** [[Geology of Shropshire]] **** [[Geology of Lizard, Cornwall]] *** [[Geology of Scotland]] *** [[Geology of Wales]] * [[Geology of the Falkland Islands]] * [[Geology of India]] ** [[Sikkim#Geology|Geology of Sikkim]] * [[Geology of Japan]] {{mid|width=64%}} * [[Geology of the United States of America]] ** ''US geology by state:'' *** [[Geology of Connecticut]] *** [[Geology of Georgia (U.S. state)|Geology of Georgia]] *** [[Geology of Idaho]] *** [[Geology of Illinois]] *** [[Geology of Minnesota]] *** [[Geology of Mississippi]] *** [[Geology of Pennsylvania]] *** [[Geology of Tennessee]] *** [[Geology of Texas]] ** ''US Geology by region or feature:'' *** [[Geology of the Appalachians]] *** [[Geology of the Pacific Northwest]] *** [[Geology of the Bryce Canyon area]]''(Utah)'' *** [[Geology of the Canyonlands area]] ''(Utah)'' *** [[Geology of the Capitol Reef area]] ''(Utah)'' *** [[Geology of the Death Valley area]] ''(California)'' *** [[Geology of the Grand Canyon area]] ''(Arizona)'' *** [[Geology of the Grand Teton area]] ''(Wyoming)'' *** [[Geology of the Lassen area]] ''(California)'' *** [[Mount Adams (Washington)#Geology|Geology of Mount Adams]] ''(Washington)'' *** [[Geology of Mount Shasta]] ''(California)'' *** [[Geology of the Yosemite area]] ''(California)'' *** [[Geology of the Zion and Kolob canyons area]] ''(Utah)'' *** [[Glacial geology of the Genesee River]] ''(New York, Pennsylvania)'' {{bottom}} ==Planetary geology== {{see also|Geology of solar terrestrial planets}} [[Image:Viking2 frost enhance.jpg|thumb|right|300px|Surface of Mars as photographed by the [[Viking 2]] lander [[December 9]], [[1977]].]] * [[Geology of Mercury]] * [[Geology of Venus]] * [[Geology of the Moon]] * [[Geology of Mars]] ==References== {{reflist}} ==See also== <div class="references-small" style="-moz-column-count:3; column-count:3;"> * [[Agrogeology]] * [[Geochemistry]] * [[Geologist]] * [[Geologic modeling]] * [[Geologic time scale]] * [[Glossary of geology terms]] * [[International Union of Geological Sciences]] ([[IUGS]]) * [[List of geology topics]] * [[List of fossil sites]] ''(with link directory)'' * [[List of minerals]] * [[List of rock types]] * [[List of publications in geology|Important publications in geology]] * [[List of rock textures]] * [[Mineral]] * [[Timeline of geology]] * [[Paleorrota]] </div> ==External links== * geology.com - [http://geology.com ''Earth Science News, Maps, Dictionary, Articles, Jobs''] * James Hutton's [http://www.mala.bc.ca/~johnstoi/essays/Hutton.htm ''Theory of the Earth''] * James Hutton's [http://www.uwmc.uwc.edu/geography/hutton/hutton.htm ''Theory of the Earth & Abstract of the Theory of the Earth''] {{Earth science}} {{Nature nav}} [[Category:Geology| ]] [[af:Geologie]] [[am:መሬት ጥናት (ጂዮሎጂ)]] [[ar:جيولوجيا]] [[an:Cheolochía]] [[ast:Xeoloxía]] [[map-bms:Geologi]] [[ba:Геология]] [[bs:Geologija]] [[br:Douarouriezh]] [[bg:Геология]] [[ca:Geologia]] [[cs:Geologie]] [[cy:Daeareg]] [[da:Geologi]] [[de:Geologie]] [[et:Geoloogia]] [[el:Γεωλογία]] [[es:Geología]] [[eo:Geologio]] [[eu:Geologia]] [[fa:زمین‌شناسی]] [[fo:Jarðfrøði]] [[fr:Géologie]] [[fy:Geology]] [[ga:Geolaíocht]] [[gd:Eòlas-talmhainn]] [[gl:Xeoloxía]] [[ko:지질학]] [[hr:Geologija]] [[io:Geologio]] [[id:Geologi]] [[ia:Geologia]] [[ie:Geologie]] [[iu:ᓄᓇᓕᕆᓂᖅ/nunaliriniq]] [[is:Jarðfræði]] [[it:Geologia]] [[he:גאולוגיה]] [[jv:Geologi]] [[kaa:Geologiya]] [[ky:Геология]] [[ku:Geolojî]] [[lad:Jeolojiya]] [[la:Geologia]] [[lv:Ģeoloģija]] [[lb:Geologie]] [[lt:Geologija]] [[li:Geologie]] [[jbo:ligytedyske]] [[hu:Geológia]] [[mi:Tātai aro whenua]] [[mn:Геологи]] [[nah:Tlālmatiliztli]] [[nl:Geologie]] [[ja:地質学]] [[no:Geologi]] [[nn:Geologi]] [[nrm:Géologie]] [[nov:Geologia]] [[om:Geology]] [[ps:ځمکپېژندنه]] [[pl:Geologia]] [[pt:Geologia]] [[ro:Geologie]] [[ru:Геология]] [[sco:Geologie]] [[sq:Gjeologjia]] [[scn:Gioluggìa]] [[simple:Geology]] [[sl:Geologija]] [[sr:Геологија]] [[sh:Geologija]] [[su:Géologi]] [[fi:Geologia]] [[sv:Geologi]] [[tl:Heolohiya]] [[ta:நிலவியல்]] [[th:ธรณีวิทยา]] [[vi:Địa chất học]] [[tg:Геология]] [[tr:Yerbilim]] [[uk:Геологія]] [[ur:ارضیات]] [[vec:Giołogia]] [[vo:Talav]] [[fiu-vro:Geoloogia]] [[wa:Djeyolodjeye]] [[yi:געאלאגיע]] [[zh-yue:地質學]] [[bat-smg:Geoluogėjė]] [[zh:地质学]] [[sk:Geológia]]