The balance between changes within the Earth's crust and mantle, where material is displaced in response to an increase (isostatic depression) or decrease (isostatic rebound) in mass at any point on t
he Earth's surface above. Such changes are frequently caused by advances or retreats of glaciers.
Isostasy refers to the response of the earth to changes in surface load. It includes the deformational and gravitational response. This response is elastic on short time scales, as in the earth-ocean
response to recent changes in mountain glaciation, or viscoelastic on longer time scales, as in the response to the last deglaciation following the Last Glacial Maximum. See also Glacial Isostatic Adjustment (GIA).
The movement of the solid part of the earth until it is in balance; also called isostatic compensation. The prime example of isostatic adjustment is the continents "floating" on the denser parts of th
e crust.
Large scale sinking of the crust into the asthenosphere because of an increase in weight on the crustal surface. Common in areas of continental glaciation where the crust was depressed by the weight o
f the ice.
Post-glacial rebound (sometimes called continental rebound, isostatic rebound, isostatic adjustment or post-ice-age isostatic recovery) is the rise of land masses that were depressed by the huge weigh
t of ice sheets during the last glacial period, through a process known as isostatic depression. [Wikipedia]