Postglacial Uplift of Scandinavia and Physical Nature of Viscosity of the Earth's Upper Mantle

There are many reasons to assume isostatic readjustment taking place in the low-velocity layer. In this case postglacial uplift of Scandinavia gives the value 1020–1021 for viscosity in the low-velocity layer. Assuming the low-velocity layer being composed principally of Mg silicates it is possible to calculate respective viscosity due to diffusional processes. Thus for viscosity the value 1019–1022 was obtained which is in reasonable agreement with respective value from the uplift data.