Geometry of Quaternary sediments along the north Norfolk coast, UK: a shallow seismic study

Abstract

Seismic refraction profiles on land and marine single-channel seismic profiling in inshore waters were used to supplement shallow-borehole data to determine the overall form of the Quaternary sequence in the coastal zone of North Norfolk. Refraction data from five principal profiles across the zone shows four velocity units, and correlation with the borehole data indicates that these (principally) represent (a) the surface drained/weathered zone, (b) Holocene and glacial sediments, (c) weathered chalk, and (d) fresh chalk. A strong reflection on two marine profiles is interpreted as the top of the Chalk. Integration of the data shows that Quaternary sediments are contained in a broad, shallow, east–west trending trough centred along the marshes, landward of barrier sediments. This trough extends eastwards beyond the present shoreline into the southern North Sea. The linearity of the axis of the trough and the adjacent coastline suggests an underlying structural control that may be east–west faulting on the northern side of the London–Brabant Massif.