Seismic refraction studies of geological structure in the inner part of the Bristol Channel

Abstract

Nine E–W seismic refraction lines about 12 km long provide information on the thickness and structure of the Mesozoic succession in the inner Bristol Channel area. About 2000 m of mainly Jurassic strata occupy the Bristol Channel syncline north of Foreland Point but this structure attenuates eastwards and is replaced by the Glastonbury syncline which contains nearly 800 m of Mesozoic strata under Bridgwater Bay. The Central Bristol Channel fault zone has been traced eastwards towards Bridgwater Bay, and has a southerly downthrow of several hundred metres in mid-Channel north of Porlock. There is some evidence for an early phase of movement along the fault zone, bringing Lower Palaeozoic against Upper Palaeozoic rocks.