Editing Geology (section)

===Plate tectonics===
{{Main|Plate tectonics}}
[[File:Plates tect2 en.svg|thumb|upright=1.35|The major [[tectonic plates]] of the [[Earth]]<ref>{{Cite web|url=https://ocre-geoscience.com/ocre-geomap/|title=OCRE GeoMap|website=OCRE Geoscience Services}}</ref>]]

In the 1960s, it was discovered that the Earth's [[lithosphere]], which includes the [[Crust (geology)|crust]] and rigid uppermost portion of the [[upper mantle]], is separated into [[tectonic plate]]s that move across the [[Plasticity (physics)|plastically]] deforming, solid, upper mantle, which is called the [[asthenosphere]]. This theory is supported by several types of observations, including seafloor spreading<ref>Hess, H. H. (November 1, 1962) "[http://repositories.cdlib.org/sio/lib/23 History Of Ocean Basins]. {{Webarchive|url=https://web.archive.org/web/20091016025000/http://repositories.cdlib.org/sio/lib/23|date=2009-10-16}}", pp. 599–620 in ''Petrologic studies: a volume in honor of A. F. Buddington''. A. E. J. Engel, Harold L. James, and B. F. Leonard (eds.). [[Geological Society of America]].</ref><ref name="TDE discovery">{{Cite book |last1=Kious |first1=Jacquelyne |author2=Tilling, Robert I. |others=Kiger, Martha, Russel, Jane |title=This Dynamic Earth: The Story of Plate Tectonics |publisher=United States Geological Survey |location=Reston |year=1996 |edition=Online |chapter=Developing the Theory |isbn=978-0-16-048220-5 |chapter-url=http://pubs.usgs.gov/gip/dynamic/understanding.html |access-date=13 March 2009 |archive-date=10 August 2011 |archive-url=https://web.archive.org/web/20110810162308/http://pubs.usgs.gov/gip/dynamic/understanding.html |url-status=live }}</ref> and the global distribution of mountain terrain and seismicity.

There is an intimate coupling between the movement of the plates on the surface and the [[mantle convection|convection of the mantle]] (that is, the [[heat]] transfer caused by the slow movement of ductile mantle rock). Thus, oceanic parts of plates and the adjoining mantle [[convection currents]] always move in the same direction – because the oceanic lithosphere is actually the rigid upper thermal [[boundary layer]] of the convecting mantle. This coupling between rigid plates moving on the surface of the Earth and the convecting [[Mantle (geology)|mantle]] is called plate [[tectonics]].

The development of plate tectonics has provided a physical basis for many  observations of the solid [[Earth]]. Long linear regions of geological features are explained as plate boundaries:<ref name="TDE plates">{{Cite book |last1=Kious |first1=Jacquelyne |author2=Tilling, Robert I. |others=Kiger, Martha, Russel, Jane |title=This Dynamic Earth: The Story of Plate Tectonics |publisher=United States Geological Survey |location=Reston, VA |date=1996 |edition=Online |chapter=Understanding Plate Motions |isbn=978-0-16-048220-5 |chapter-url=http://pubs.usgs.gov/gip/dynamic/understanding.html |access-date=13 March 2009 |archive-date=10 August 2011 |archive-url=https://web.archive.org/web/20110810162308/http://pubs.usgs.gov/gip/dynamic/understanding.html |url-status=live }}</ref>
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[[File:Active Margin.svg|thumb|Oceanic-continental convergence resulting in [[subduction]] and [[volcanic arc]]s illustrates one effect of [[plate tectonics]].]]
* [[Mid-ocean ridge]]s, high regions on the seafloor where [[hydrothermal vent]]s and volcanoes exist, are seen as [[divergent boundary|divergent boundaries]], where two plates move apart.
* Arcs of volcanoes and earthquakes are theorized as [[convergent boundaries]], where one plate [[subducts]], or moves, under another.
* [[Transform boundary|Transform boundaries]], such as the [[San Andreas Fault]] system, are where plates slide horizontally past each other. 

Plate tectonics has provided a mechanism for [[Alfred Wegener]]'s theory of [[continental drift]],<ref>{{Cite book |author=Wegener, A. |url=https://archive.org/details/originsofcontine0000unse |title=Origin of continents and oceans |publisher=Courier Corporation |year=1999 |isbn=978-0-486-61708-4 |url-access=registration}}</ref> in which the [[continents]] move across the surface of the Earth over geological time. They also provided a driving force for crustal deformation, and a new setting for the observations of structural geology. The power of the theory of plate tectonics lies in its ability to combine all of these observations into a single theory of how the lithosphere moves over the convecting mantle.