Lithospheric thickness and crustal uplift dimensions are calculated numerically as functions of time after the onset of a convective transfer of heat into the lithosphere by magma intrusion. The numerical models show that the rate of lithospheric thinning depends on the rate or magma entry into the lithosphere and the initial temperature regime of the lithosphere. The width and height of uplift for continental regions depends on (1) the apparent flexural regidity of the lithosphere, (2) the diameter of the hot spot beneath the lithosphere, (3) the density contrast between the new asthenosphere and the original lithosphere, (4) erosion rates, and (5) the rate of magma entry into the lithosphere. For oceanic lithosphere the amount of uplift depends on points 1, 2, and 3 above, on the eruption depth, and on the size of the volcanic load (if any). With reasonable values for these parameters the model produces crustal uplift rates and lithospheric deflections similar to those observed for continental rifts and Hawaii. The model suggests that a fractured lithosphere beneath Hawaii is not necessary. Volcanic loading combined with the uplift produced by lithospheric thinning can produce an arch with an amplitude comparable to that of the Hawaiian arch. The model applied to moving plates suggests that the lithosphere/asthenosphere boundary is asymmetrically distorted in the direction of plate movement.