Article
Article
Isostasy
Article By:
Bell, Robin E. Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York.
Coakley, Bernard J. Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York.
Last reviewed:November 2019
DOI:https://doi.org/10.1036/1097-8542.356500
The application of Archimedes' principle to the layered structure of the Earth. The elevated topography of Earth is roughly equivalent to an iceberg that floats in the surrounding, denser water. Just as an iceberg extends beneath the exposed ice, the concept of isostasy proposes that topography is supported, or compensated, by a deep root. The buoyant outer shell of the Earth, the crust, displaces the denser, viscous mantle in proportion to the surface elevation. Isostasy implies the existence of a level surface of constant pressure within the mantle, the depth of compensation. Above this surface the mass of any vertical column is equal. Equal pressure at depth can also be achieved by varying density structure or by the regional deflection of the lithosphere. See also: Archimedes' principle; Earth crust
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