England and Molnar, 1990, Geology, v. 18, pp. 1173-1177.

Uplift = displacement component in the direction opposite to the gravity vector.

Important definitions:
1) Surface uplift: Displacement of the earth's surface with respect to the geoid (equipotential surface of equal gravity magnitude and always perpendicular to the local gravtiy vector).

2) Uplift of rocks: Displacement of rocks with respect to the geoid.

3) Exhumation: Displacement of rocks with respect to the surface. The rate of exhumation is the rate of erosion or the rate of removal of overburden by tectonic processes.

Surface uplift = uplift of rock - exhumation

Surface uplift is the important parameter for understanding tectonic forces acting in mountain belts.

Uplift of rock is useful for mass balance calculations.

Measuring surface uplift:
Geodesy
Paleoflora
Marine terraces (assuming that sea level can be reconstructed).

Measuring exhumation:
Geobarometry or geothermometry (assuming a geothermal gradient).