(Cont.) This is the first time that an alternation between thrusting and normal faulting has been observed in an over-riding plate during continent-continent collision, and only the second time that it has ever been documented in a collisional orogen. The data imply that there was a fundamental cyclicity between crustal thickening and thinning, consistent with dynamical models of orogenesis in which plate-forces responsible for contraction and gravitational forces responsible for extension, oscillate between periods where one dominates. Furthermore, given the established relationship between topography and synorogenic extension in active mountain belts, it is likely that activity along the Tindern detachment, the earliest splay of the FRD, was controlled by Caledonian paleotopography that formed during the initial stages of orogenesis. The fact that most middle- and upper-crustal extension was restricted to the FRD implies that a localized inherent crustal weakness may have developed after initial movement along the Tindern detachment. Given that late-stage Devonian activity on the FRD may have played a prominent role in the formation of the Devonian basins, which themselves likely controlled the geometry and location of subsequent Mesozoic extension and formation of the North Sea basins, the implication is that the position of rifting of the north Atlantic ocean was partially [pre-determined] inherited from the initial Caledonian paleotopography.