This paper gives calculations and computations, based on simple ideal conditions, of the possible disturbances of underground temperatures caused by uplift and denudation. The effects of the speed of denudation, the rate of uplift, and the time during which these two processes may have been operating, are illustrated by numerical tables applying to some specific ideal situations. The resulting disturbance of the heat flow in the earth (which is evaluated by making use of underground temperature gradients) is discussed. It is shown that uplift and denudation increase the heat flow above its equilibrium value, but that no very large increase is likely to occur unless the equilibrium heat flow is small and the speed of denudation is large.