ISOSTASY

isostasy

(noun) (geology) a general equilibrium of the forces tending to elevate or depress the earth’s crust

Source: WordNet® 3.1

Etymology

Noun

isostasy (usually uncountable, plural isostasies)

(geology) The state of balance or pressure equilibrium thought to exist within the Earth's crust, whereby the upper lithosphere floats on denser magma beneath.

Source: Wiktionary

I*sos"ta*sy, n. [See Iso-; Stasis.]

Definition: The state or quality of being isostatic. Specif. (Geol.),

Definition: general equilibrium in the earth's crust, supposed to be maintained by the yielding or flow of rock material beneath the surface under gravitative stress. By the theory of isostasy each unit column of the earth, from surface to center, has approximately the same weight, and the continents stand higher than the ocean beds chiefly because the material of the crust has there less density.

Source: Webster’s Unabridged Dictionary 1913 Edition