A model for the equilibrium of the Pine Mountain block of the southern Appalachians shows that fault-zone drag is the most important energy sink. However, internal deformation accompanying bending at ramps is significant and makes fault-zone drag a poor estimate of the total energy dissipated in movement for reasonable model parameters. In none of the models considered can gravity provide the energy necessary to move the Pine Mountain block. A regional compression on the order of a kilobar is also necessary. However, gravity sliding is untenable as a source for this regional compression because (1) there is no evidence for a forward-dipping sole fault now or at the time of deformation as required by this model and (2) a gravity sliding model is inconsistent with some geological observations. But there is no evidence for or against a forward-dipping erosional surface, a critical aspect of the so-called 'glacier analogy' model. However, unlike gravity sliding, the existence of a forward-dipping erosional surface at the time of deformation is not inconsistent with known geology. Any solution to the problem of driving forces for fold and thrust belts must consider not only paleotopography but also processes taking place in the interior of mountain belts.