The constant area (constant volume) assumption is generally valid for deformation that has occurred in upper crustal, nonmetamorphic settings, but there are important exceptions. For example, in some settings syntectonic deposition and compaction can result in substantial rock volume changes throughout the course of deformation. In these cases, approximations of the volume changes must be incorporated in the balancing process. | The constant area (constant volume) assumption is generally valid for deformation that has occurred in upper crustal, nonmetamorphic settings, but there are important exceptions. For example, in some settings syntectonic deposition and compaction can result in substantial rock volume changes throughout the course of deformation. In these cases, approximations of the volume changes must be incorporated in the balancing process. |