Age-dependent rheology profiles (viscosity) for (A) Archean Baltica/Reguibat shield (Paleo-Proterozoic margins) and (B) Phanerozoic lithosphere involved in Africa-Europe convergence. Thickness, temperature and composition determine the depths and numbers of mechanical decoupling levels in crust and mantle. These two contrasting rheological profiled ultimately define lateral viscosity profiles that reproduce well the first order pattern of current stresses and basal traction exerted by mantle flow at the base of the continents (C). The mantle heat flux Qm is larger for the Phanerozoic lithosphere to explain the lack of thermal relaxation.