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| − | '''Earth science''' (also known as '''geoscience''', '''the geosciences''' or '''the Earth Sciences'''), is an all-embracing term for the [[science]]s related to the planet [[Earth (planet)|Earth]]. [http://wordnet.princeton.edu/perl/webwn?s=earth%20science Wordnet Search: Earth science] It is arguably a special case in [[planetary science]], the Earth being the only known [[life]]-bearing planet. There are both [[reductionist]] and [[holism|holistic]] approaches to Earth science. The major historic [[discipline]]s use [[physics]], [[geology]], [[geography]], [[meteorology]], [[mathematics]], [[chemistry]] and [[biology]] to build a quantitative understanding of the principal areas or ''[[Earth's spheres|spheres]]'' of the Earth system.
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| − | == Earth's spheres ==
| + | '''Earth science''' (also known as geoscience, the geosciences or the Earth sciences) is an all-embracing term for the [[sciences]] related to the planet [[Earth]]. It is taken to be a special case in [[planetary science]], given the Earth is the only life-bearing planet currently discovered. There are both [[reductionist]] and [[holistic]] approaches to [[Earth]] sciences. The formal [[discipline]] of Earth sciences may include the [[study]] of the [[atmosphere]], hydrosphere, [[oceans]] and biosphere, as well as the solid [[earth]]. Typically Earth scientists will use [[tools]] from [[physics]], [[chemistry]], [[biology]], and [[mathematics]] to build a [[quantitative]] [[understanding]] of how the Earth system works, and how it evolved to its current state. |
| − | Earth science generally recognizes 4 spheres, the lithosphere, the hydrosphere, the atmosphere, and the biosphere. | |
| − | [http://www2.cet.edu/ete/hilk4/intro/spheres.html Earth's Spheres]. ©1997-2000. Wheeling Jesuit University/NASA Classroom. These correspond to rocks, water, air, and life. Some practitioners include the cryosphere (ice) as a distinct portion of the hydrosphere and the pedosphere (soil) as an active, intermixed sphere as part of Earth's spheres. | |
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| − | *[[Geology]] describes the [[Rock (geology)|rocky]] parts of the Earth's [[Crust (geology)|crust]] (or [[lithosphere]]) and its historic development. Major subdisciplines are [[mineralogy]] and [[petrology]], [[geochemistry]], [[geomorphology]], [[paleontology]], [[stratigraphy]], [[Structural geology|structural geology]], [[engineering geology]] and [[sedimentology]].
| + | The following fields of [[science]] are generally categorized within the geosciences: |
| − | *[[Geophysics]] and [[Geodesy]] investigate the [[figure of the Earth]], its reaction to forces and its [[magnetic field|magnetic]] and [[gravity field]]s. Geophysicists explore the [[Earth's core]] and [[Earth's mantle|mantle]] as well as the [[Plate tectonics|tectonic]] and [[Seismology|seismic]] activity of the lithosphere.<ref name="smith 5" [http://wordnet.princeton.edu/perl/webwn?s=geodesy Wordnet Search: Geodesy] [http://www.oceanservice.noaa.gov/education/kits/geodesy/welcome.html NOAA National Ocean Service Education: Geodesy]
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| − | *[[Soil science]] covers the outermost layer of the Earth's crust that is subject to soil formation processes (or [[pedosphere]]). [http://soil.gsfc.nasa.gov/ped/pedosph.htm Elissa Levine, 2001, The Pedosphere As A Hub] Major subdisciplines include [[edaphology]] and [[Pedology (soil study)|pedology]]. [http://jan.ucc.nau.edu/~doetqp-p/courses/env320/lec1/Lec1.html Duane Gardiner, Lecture: Why Study Soils? excerpted from Miller, R.W. & D.T. Gardiner, 1998. Soils in our Environment, 8th Edition]
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| − | *[[Oceanography]] and [[hydrology]] (includes [[limnology]]) describe the marine and freshwater domains of the [[water]]y parts of the Earth (or [[hydrosphere]]). Major subdisciplines include [[hydrogeology]] and [[Physical oceanography|physical]], [[Chemical oceanography|chemical]], and [[Marine biology|biological]] oceanography.
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| − | *[[Glaciology]] covers the [[ice|icy]] parts of the Earth (or [[cryosphere]]).
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| − | *[[Atmospheric sciences]] cover the [[gas]]eous parts of the Earth (or [[Earth's atmosphere|atmosphere]]) between the surface and the [[exosphere]] (~1000 km). Major subdisciplines are [[meteorology]], [[climatology]], [[atmospheric chemistry]] and [[atmospheric physics]].
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| − | *A very important linking sphere is the biosphere, the study of which is [[biology]]. The biosphere consists of all forms of life, from single-celled organisms to pine trees to people. The interactions of Earth's other spheres - lithosphere/geosphere, hydrosphere, atmosphere and/or cryosphere and pedosphere - create the conditions that can support life.
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| − | ==Earth's interior==
| + | *[https://en.wikipedia.org/wiki/Geology Geology] describes the rocky parts of the Earth's crust (or [https://en.wikipedia.org/wiki/Lithosphere lithosphere]) and its historic development. Major subdisciplines are mineralogy and petrology, geochemistry, geomorphology, [https://en.wikipedia.org/wiki/Paleontology paleontology], [https://en.wikipedia.org/wiki/Stratigraphy stratigraphy], structural geology, engineering geology and sedimentology. |
| | + | *[https://en.wikipedia.org/wiki/Physical_geography Physical geography] covers the aspects of [https://en.wikipedia.org/wiki/Geomorphology geomorphology], [https://en.wikipedia.org/wiki/Oceanography oceanography], climatology and biogeography.[citation needed] |
| | + | *[https://en.wikipedia.org/wiki/Geophysics Geophysics] and geodesy [[investigate]] the shape of the [[Earth]], its reaction to forces and its [[magnetic]] and [[gravity]] fields. Geophysicists explore the [https://en.wikipedia.org/wiki/Earth%27s_core Earth's core] and [https://en.wikipedia.org/wiki/Earth%27s_mantle mantle] as well as the tectonic and seismic activity of the lithosphere. |
| | + | *[https://en.wikipedia.org/wiki/Soil_science Soil science] covers the outermost layer of the Earth's crust that is subject to soil formation processes (or [https://en.wikipedia.org/wiki/Pedosphere pedosphere]). Major subdisciplines include edaphology and pedology. |
| | + | *[https://en.wikipedia.org/wiki/Oceanography Oceanography] and hydrology (includes limnology) describe the marine and freshwater domains of the watery parts of the Earth (or hydrosphere). Major subdisciplines include hydrogeology and physical, chemical, and biological oceanography.[citation needed] |
| | + | *[https://en.wikipedia.org/wiki/Glaciology Glaciology] covers the icy parts of the Earth (or cryosphere). |
| | + | *[https://en.wikipedia.org/wiki/Atmospheric_sciences Atmospheric sciences] cover the [[gaseous]] parts of the Earth (or [[atmosphere]]) between the surface and the [https://en.wikipedia.org/wiki/Exosphere exosphere] (about 1000 km). Major subdisciplines are meteorology, climatology, atmospheric chemistry and atmospheric physics.[https://en.wikipedia.org/wiki/Earth_science] |
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| − | In [[geology]], [[plate tectonics]], [[mountain|mountain range]]s, [[volcano]]es, and [[earthquake]]s are phenomena that can be explained in terms of [[energy transformation]]s in the [[Earth's crust]].<ref>[http://okfirst.ocs.ou.edu/train/meteorology/EnergyBudget.html Earth's Energy Budget]</ref>
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| − | Beneath the earth's [[lithosphere|crust]] lies the [[Earth's mantle|mantle]] which is heated by the radioactive decay of heavy elements. The mantle is not quite solid and consists of [[magma]] which is in a state of semi-perpetual [[wiktionary:convection|convection]]. This convection process causes the lithospheric plates to move, albeit slowly. The resulting process is known as [[plate tectonics]].<ref>Simison par. 7 Adams 94,95,100,102 Smith 13-17,218,G-6, Oldroyd 101,103,104
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| − | Plate tectonics might be thought of as the process by which the earth resurfaces itself. Through a process called ''spreading ridges'' (or [[seafloor spreading]]), the earth creates new crust by allowing magma underneath the lithosphere to come to the surface where it cools and solidifies--becoming new crust, and through a process called [[subduction]], excess crust is pushed underground--beneath the rest of the lithosphere--where it comes into contact with magma and melts--rejoining the mantle from which it originally came.
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| − | Areas of the crust where new crust is created are called ''divergent boundaries'', and areas of the crust where it is brought back into the earth are called ''convergent boundaries''. There is another type of boundary called a [[transform boundary]] where plates slide in opposite directions but no new lithospheric material is created or destroyed (Smith 331).</ref> [[Earthquakes]] result from the movement of the lithospheric plates, and they often occur near covergent boundaries where parts of the crust are forced into the earth as part of subduction.
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| − | [[Volcanoes]] result primarily from the melting of subducted crust material. Crust material that is forced into the athenosphere melts, and some portion of the melted material becomes light enough to rise to the surface--giving birth to volcanoes.
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| − | == Earth's electromagnet ==
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| − | An [[electromagnet]] is a magnet that is created by a current that flows around a soft-iron core. The earth has a soft iron [[Earth core|core]] surrounded by semi-liquid materials from the mantle that move in continuous currents around the core; The earth has a solid iron inner core surrounded by a liquid outer core therefore, the earth is an [[Wiktionary:electromagnet|electromagnet]]. This is referred to as the [[dynamo theory]] of earth's magnetism.|url=http://setiathome.berkeley.edu/~pauld/etc/210BPaper.pdf], Dynamo Theory and Earth's Magnetic Field., by Demorest, Paul. The fact that earth is an electromagnet helps with the earth's maintenance of an atmosphere suitable for life.
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| − | == Atmosphere ==
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| − | The earth is blanketed by an [[atmosphere]] consisting of 99% oxygen and nitrogen.<ref name="adams atmosphere". The atmosphere has five layers: [[troposphere]], [[stratosphere]], [[mesosphere]], [[thermosphere]], and [[exosphere]]; and 75% of the atmosphere's gasses are in the bottom-most layer, the troposphere.
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| − | The [[magnetic field]] created by [[Earth's mantle|mantle's]] internal motions produces the [[magnetosphere]] which protects the earth's atmosphere from the solar wind.<ref>Adams 21-22</ref> It is theorized that the solar wind would strip away earth's atmosphere in a few million years were it not for the earth's electromagnet. And since earth is [[Age of the earth|4.5 billion]] years old,<ref name="age earth">Smith 183</ref> earth would not have an atmosphere by now if there were no magnetosphere.
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| − | The atmosphere is composed of 78% [[nitrogen]] and 21% [[oxygen]]. The remaining one percent contains small amounts of other gasses including CO,<sub>2</sub> and water vapors. Water vapors and CO<sub>2</sub> allow the earth's atmosphere to catch and hold the sun's energy through a phenomenon called the [[greenhouse effect]]. This allows earth's surface to be warm enough to have liquid water and support life.
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| − | In addition to storing heat, the atmosphere also protects living organisms by shielding the earth's surface from [[cosmic rays]]. Note that the level of protection seems to be adjusted to prevent cosmic rays from destroying all life while allowing for the [[mutations]] that have an important role in pushing forward [[evolution|diversity]] in the biosphere.
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| − | ==Methodology==
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| − | Like all other scientists, Earth scientists apply the [[scientific method]]. They formulate [[hypotheses]] after observing events and gathering data about natural phenomena, and then they test those hypotheses. In Earth science, data usually plays a major role in testing and formulating hypotheses.
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| − | A driving philosophical force behind contemporary earth science is [[uniformitarianism (science)|uniformitarianism]]. Uniformitarianism says that "ancient geologic features are interpreted by understanding active processes that are readily observed". Simply stated, this means that dramatic and awe-inspiring features of the earth can be explained by the actions of gradual processes operating over long periods of time; for example, a mountain need not be thought of as having been created in a moment, but instead it may be seen as the result of earthquake after earthquake raising the ground in a certain area by small amounts over millions of years.
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| − | == Partial list of the major Earth Science topics ==
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| − | ===Atmosphere===
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| − | * [[Atmospheric chemistry]]
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| − | * [[Climatology]]
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| − | * [[Meteorology]]
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| − | ** [[Hydrometeorology]]
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| − | * [[Paleoclimatology]]
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| − | ===Biosphere===
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| − | * [[Biogeography]]
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| − | * [[Paleontology]]
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| − | ** [[Palynology]]
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| − | ** [[Micropaleontology]]
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| − | * [[Geomicrobiology]]
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| − | ===Hydrosphere===
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| − | * [[Hydrology]]
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| − | ** [[Glaciology]]
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| − | ** [[Limnology]]
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| − | * [[Hydrogeology]]
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| − | * [[Oceanography]]
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| − | ** [[Chemical oceanography]]
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| − | ** [[Marine biology]]
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| − | ** [[Marine geology]]
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| − | ** [[Paleoceanography]]
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| − | ** [[Physical oceanography]]
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| − | === Lithosphere or geosphere===
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| − | * [[Geology]]
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| − | ** [[Economic geology]]
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| − | ** [[Engineering geology]]
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| − | ** [[Environmental geology]]
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| − | ** [[Historical geology]]
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| − | *** [[Glaciology]]
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| − | *** [[Quaternary geology]]
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| − | ** [[Planetary geology]]
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| − | ** [[Sedimentology]]
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| − | ** [[Stratigraphy]]
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| − | ** [[Structural geology]]
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| − | * [[Geochemistry]]
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| − | * [[Geography]]
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| − | ** [[Physical geography]]
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| − | * [[Geomorphology]]
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| − | * [[Geophysics]]
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| − | ** [[Geochronology]]
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| − | ** [[Geodynamics]] (see also [[Tectonics]])
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| − | ** [[Geomagnetic]]s
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| − | ** [[Gravimetry]] (also part of [[Geodesy]])
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| − | ** [[Seismology]]
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| − | * [[Hydrogeology]]
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| − | * [[Mineralogy]]
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| − | ** [[Crystallography]]
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| − | ** [[Gemology]]
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| − | * [[Petrology]]
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| − | * [[Volcanology]]
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| − | ===Pedosphere===
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| − | * [[Soil science]]
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| − | ** [[Edaphology]]
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| − | ** [[Pedology (soil study)|Pedology]]
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| − | ===Systems===
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| − | * [[Environmental science]]
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| − | * [[Geography]]
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| − | ** [[Human geography]]
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| − | ** [[Physical geography]]
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| − | * [[Gaia hypothesis]]
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| − | ===Others===
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| − | * [[Cartography]]
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| − | * [[Geoinformatics]] ([[GIS]])
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| − | * [[Geostatistics]]
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| − | * [[Geodesy]] and [[Surveying]]
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| − | ==See also==
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| − | * [[List of basic earth science topics]]
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| − | * [[List of geoscience organizations]]
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| − | * [[Structure of the Earth]]
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| | [[Category: General Reference]] | | [[Category: General Reference]] |
| − | [[Category:Physical sciences]] | + | [[Category: Earth Science]] |
