It’s Egypt! Trust me. I had the same question and it was right ;)
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Relation between buoyancy, isostatic equilibrium, and epeirogenic processes</u></h2>
Buoyant force or buoyancy, is the force exerted in an object which is fully or partially occupied in a fluid. Isostatic equilibrium is the gravitational equilibrium between earth's crust and underlying mantle. while epeirogenic process is the depression of land having long wavelengths.
Both epeirogenic process and isostatic equilibrium uses the principle of buoyancy. The crust of the Earth or the lithosphere floats over underlying mantle at an elevation depending upon its density and thickness.
