What is the name for the principle that brings floating crust into gravitional balance?

The principle that brings floating crust into gravitational balance is called isostasy. It describes how the Earth's lithosphere (the rigid outer layer) maintains equilibrium by adjusting its thickness and elevation in response to changes in load, such as ice, water, or sediment. This balance is achieved through the buoyancy of the lithosphere as it "floats" on the denser, more fluid asthenosphere beneath it.