An uplift or depression of the Earth's crust, affecting large areas of land or of the bottoms of oceans: An epeirogeny is the deformation of the Earth's crust by which continents and ocean basins are produced.

Basins and plateaus are often formed as the result of epeirogeny.

Epeirogeny differs from orogeny in that it affects larger regions of the Earth's crust and is not as frequently associated with the folding and the faulting of rocks.