What causes isostasy?

Isostasy is caused by the gravitational equilibrium between the Earth's lithosphere and asthenosphere, which allows the crust to "float" at varying elevations based on its density and thickness. When geological processes, such as erosion or sediment deposition, alter the mass of the crust, the lithosphere adjusts vertically to maintain balance. This adjustment can lead to uplift or subsidence as the Earth's crust responds to changes in surface load, such as glacial ice or mountain ranges. Essentially, isostasy reflects the principle that the Earth's crust seeks to maintain equilibrium under varying conditions.