Bristol Channel Fault Zone

The Bristol Channel Fault Zone or Central Bristol Channel Fault Zone is a major south-dipping geological fault, or zone of faulting, running approximately west-east in the Bristol Channel between England and Wales. It makes landfall just south of Weston-super-Mare and the Mendip Hills. It forms a divide between the late Palaeozoic age South Wales basin to the north and the Culm Basin to the south. It marks a major change in the pre-Variscan geology of the United Kingdom, juxtaposing very different sequences of Devonian and Lower Carboniferous rocks. During the Variscan, the fault may have acted as either a strike-slip fault or a thrust fault or indeed both; its nature remains uncertain. During the Triassic to Jurassic, the fault zone was active as an extensional fault, controlling the development of the Bristol Channel Basin.