Isostasy

Mechanism whereby areas of the crustOutermost layer of a differentiated planet, asteroid or moon, usually consisting of silicate rock and extending no more than 10s of km from the surface. The term is also applied to icy bodies, in which case it is composed of ices, frozen gases, and accumulated meteoritic material. On Earth, the Click on Term to Read More rise or subside until the mass of their topography is buoyantly supported or compensated by the thickness of crust below, which “floats” on the denser mantleMain silicate-rich zone within a planet between the crust and metallic core. The mantle accounts for 82% of Earth's volume and is composed of silicate minerals rich in Mg. The temperature of the mantle can be as high as 3,700 °C. Heat generated in the core causes convection currents in Click on Term to Read More. Isostatic gravityAttractive force between all matter - one of the four fundamental forces. Click on Term to Read More anomalies are derived from the assumption that the gravitational effect of the mass associated with the surface topography is approximately compensated by a deficit of either the densityMass of an object divided by its volume. Density is a characteristic property of a substance (rock vs. ice, e.g.). Some substances (like gases) are easily compressible and have different densities depending on how much pressure is exerted upon them. The Sun is composed of compressible gases and is much Click on Term to Read More or the subsurface thickness of the crustal material.