The post-Variscan development of the British Isles within a regional transfer zone influenced by orogenesis

The break-up of Pangaea after the Variscan Orogeny included rifting extending southwards from the Barents Sea via the Norwegian–Greenland Rift and into the North Sea, and northwards from the Central Atlantic. These two major rift systems interacted to form an approximately 1200-km-wide transfer zone across the British Isles, where a complex network of basins developed during the Mesozoic. Fault patterns were commonly controlled by reactivation of Precambrian, Caledonian and Variscan structures. The two main rift systems were unable to breach this regional transfer zone, where the crust had been thickened by the Caledonian and Variscan orogenies, until the Eocene. Breaching did not occur down the North Sea and through the English Channel because of Alpine contraction in NW Europe. Instead, breaching occurred around the west of Ireland and NW Scotland, so the British Isles remained connected to Europe rather than to the North American Plate.