The sedimentary sequence on the shelf of the southern North Sea records Quaternary climatic changes in two ways. They are indicated directly by moraine and glaciofluvial deposits from the Elsterian, Saalian and Weichselian glacial periods when the British and the Scandinavian ice sheets covered parts of the area. An indirect response to the climate is indicated by sea-level changes. Phases of cooling are characterized by regressions and low sea-level stands; phases of warming are indicated by marine transgressions and high sea levels during the Holsteinian, Eemian and Holocene periods. The seismic characteristics of the different lithological units, the sedimentary sequences and their fossil content are described for the offshore area and the adjacent coastal zone. This provides a record of the interaction of sedimentary processes and the palaeogeographic development as a response to climatic changes.
Survey campaigns in an area off the Zeeland coast in the south-eastern part of the Southern Bight with sub-bottom profilers and coring and drilling equipment resulted in relatively detailed information on the sub-seabed conditions. Our data shed some new light on the origin of at least some of the ridges, investigated before by Baak (1936) and Houbolt (1968). Several of the modern Zeeland ridges seem to have been formed essentially by sand accumulation around small pre-existing sediment bodies. One of these so-called 'initial ridges' has been dated as early Atlantic. The sand which makes up the bulk of the modern ridges contains several mollusc species that are no longer living—or are very rare now—in the Southern Bight. This suggests that the ridge formation was essentially completed some time ago, before the deposition of up to 2000 years old, slightly clayey, lee-side deposits.
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