Isostasy

Isostasy (Greek ísos 'equal', stásis 'standstill') or isostatic equilibrium is the state of gravitational equilibrium between Earth's crust (or lithosphere) and mantle such that the 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,^[1] it has subsequently been interpreted in terms of lithosphere and asthenosphere, particularly with respect to oceanic island volcanoes,^[2] such as the Hawaiian Islands.

Although Earth is a dynamic system that responds to loads in many different ways,^[3] 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.^[4]^[5]^[6]

^ 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.
^ 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.
^ Watts, A. B. (2001). Isostasy and flexure of the lithosphere. Cambridge University Press. ISBN 0521622727.
^ Dutton, Clarence (1882). "Physics of the Earth's crust; discussion". American Journal of Science. 3. 23 (April): 283–290. Bibcode:1882AmJS...23..283D. doi:10.2475/ajs.s3-23.136.283. S2CID 128904689.
^ Orme, Antony (2007). "Clarence Edward Dutton (1841–1912): soldier, polymath and aesthete". Geological Society, London, Special Publications. 287 (1): 271–286. Bibcode:2007GSLSP.287..271O. doi:10.1144/SP287.21. S2CID 128576633.
^ Longwell, Chester R. (1958). "Clarence Edward Dutton" (PDF). Washington D.C.: National Academy of Sciences. Retrieved 24 March 2022.

[1] 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.

[2] 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.

[Watts2001-3] Watts, A. B. (2001). Isostasy and flexure of the lithosphere. Cambridge University Press. ISBN 0521622727.

[Dutton1882-4] Dutton, Clarence (1882). "Physics of the Earth's crust; discussion". American Journal of Science. 3. 23 (April): 283–290. Bibcode:1882AmJS...23..283D. doi:10.2475/ajs.s3-23.136.283. S2CID 128904689.

[Orme2007-5] Orme, Antony (2007). "Clarence Edward Dutton (1841–1912): soldier, polymath and aesthete". Geological Society, London, Special Publications. 287 (1): 271–286. Bibcode:2007GSLSP.287..271O. doi:10.1144/SP287.21. S2CID 128576633.

[cdutton1958-6] Longwell, Chester R. (1958). "Clarence Edward Dutton" (PDF). Washington D.C.: National Academy of Sciences. Retrieved 24 March 2022.

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