Time scales of isostatic compensations

It is generally accepted that isostatic compensations are retarded by a kind of flow process within the earth. The most famous example is the Fennoscandian uplift due to the disappearance of the Pleistocene ice sheets. The relaxation time tr of the Fennoscandian uplift during which the deviation from isostasy diminished to 1/e of its value was about 5000 years. The problem here is the dependence of tr on the characteristic wavelength L.