Editing Isostasy (section)

{{short description|State of gravitational equilibrium between Earth's crust and mantle}}

'''Isostasy''' (Greek [[wikt:ἴσος|''ísos'']] 'equal', [[wikt:στάσις|''stásis'']] 'standstill') or '''isostatic equilibrium''' is the state of [[gravity|gravitational]] [[mechanical equilibrium|equilibrium]] between [[Earth]]'s [[crust (geology)|crust]] (or [[lithosphere]]) and [[mantle (geology)|mantle]] such that the [[crust (geology)|crust]] "floats" at an elevation that depends on its thickness and density. This concept is invoked to explain how different topographic heights can exist at Earth's surface. Although originally defined in terms of [[continental crust]] and mantle,<ref>33.Spasojevic, S., and Gurnis, M., 2012, Sea level and vertical motion of continents from dynamic Earth models since the Late Cretaceous: American Association of Petroleum Geologists Bulletin, v. 96, no. 11, p. 2037–2064.</ref> it has subsequently been interpreted in terms of [[lithosphere]] and [[asthenosphere]], particularly with respect to oceanic island [[volcanoes]],<ref>13.	Foulger, G.R., Pritchard, M.J., Julian, B.R., Evans, J.R., Allen, R.M., Nolet, G., Morgan, W.J., Bergsson, B.H., Erlendsson, P., Jakobsdottir, S., Ragnarsson, S., Stefansson, R., Vogfjord, K., 2000. The seismic anomaly beneath Iceland extends down to the mantle transition zone and no deeper. Geophys. J. Int. 142, F1–F5.</ref> such as the [[Hawaiian Islands]].

Although Earth is a dynamic system that responds to loads in many different ways,<ref name=Watts2001>{{cite book |first=A. B. |last=Watts |title=Isostasy and flexure of the lithosphere |publisher=Cambridge University Press |date=2001 |isbn=0521622727}}</ref> isostasy describes the important limiting case in which crust and mantle are in [[static equilibrium]]. Certain areas (such as the [[Himalayas]] and other convergent margins) are not in isostatic equilibrium and are not well described by isostatic models.

The general term ''isostasy'' was coined in 1882 by the American geologist [[Clarence Dutton]].<ref name=Dutton1882>{{cite journal|last1=Dutton |first1=Clarence |date=1882 |title=Physics of the Earth's crust; discussion |journal=American Journal of Science |series=3 |volume=23 |issue=April |pages=283–290 |doi=10.2475/ajs.s3-23.136.283 |bibcode=1882AmJS...23..283D |s2cid=128904689 }}</ref><ref name=Orme2007>{{cite journal |last1=Orme |first1=Antony |date=2007 |title=Clarence Edward Dutton (1841–1912): soldier, polymath and aesthete |journal=Geological Society, London, Special Publications |volume=287 |issue=1 |pages=271–286 |doi=10.1144/SP287.21 |bibcode=2007GSLSP.287..271O |s2cid=128576633 }}</ref><ref name=cdutton1958>{{cite web | url=http://www.nasonline.org/publications/biographical-memoirs/memoir-pdfs/dutton-clarence.pdf | first=Chester R. | last=Longwell | publisher=National Academy of Sciences | location=Washington D.C.| title=Clarence Edward Dutton | date=1958 | access-date=24 March 2022}}</ref>