New Insights Into the Lithospheric Structure of Southern Norway

Topography can result from a balance, called isostasy, between the overlying weight of the crust and the buoyancy of the mantle beneath it. The principle of isostasy was put forward almost two centuries ago as a method of explaining variations in mountain heights, and it does a good job of explaining most of the first‐order variations in the Earth's topography. For example, when the crust is in local isostatic balance, elevation increases can be compensated for by an increase in crustal thickness, which in mountainous areas is in the form of a crustal root. Called Airy isostasy, compensation through crustal roots involves a correlation between surface topography and crustal thickness. However, topography may not be solely compensated for by crustal thickness, as other mechanisms such as flexural rigidity, low mantle densities, and dynamic topography can also be in effect.