CoachA metamorphic core complex is a dome of metamorphic rocks and mylonites, brought up from the middle or lower crust, beneath a detachment fault whose upper plate is a mosaic of tilted blocks of upper-crustal rocks. In the rolling hinge model, the detachment slips at a moderate dip at depth; as the upper plate moves away, the unloaded footwall rises by isostasy and bends, so that each part of the fault rotates to a low dip, and stops slipping, once it has passed through a hinge that migrates with the extension.
