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The modern lithosphere keeps thickening at an growing rate. Since the applied boundary force keeps constant, this increases in the rate of thickening can be related to the action of the gravitational force that promotes convergence and thickening: The cold, dense and thick SCLM keeps pulling on the lithosphere producing a couple of horizontal forces directed toward the orogen. After 25Ma the surface reaches an elevation of 6000m. It has been shown that the thickened lithospheric mantle is instable and may be dragged into the convecting asthenospheric mantle.
After a few Ma the Archaean continental lithosphere reaches a dynamical equilibrium where thickening related to convergence is balanced by thinning related to gravitational spreading in a direction perpendicular to that of convergence. This spreading is promoted that the gravitational force that is large compare to the strength of the lithosphere. After 25 Ma the surface reaches an elevation of 1000m. This experiment suggests that Archaean mountain belts do not exist!

This contrasted behaviour can be interpreted in terms of the Argand Ratio: the ratio between the gravitational force to the strength of the lithosphere. The Argand ratio measures the influence of gravity on lithospheric deformation.