GRAVELS OF SOUTHERN NORTH SEA

Gravels of six regions in the North Sea show differences in composition, grain size and roundness. It seems that the gravels in the Hinder Bank region and in front of the Thames estuary represent reworked river deposits. The material near the Suffolk coast is better rounded and is a fossil beach gravel. These deposits are formed between Lower Tertiary and Lower Holocene. Further northward the gravel belt off the British coast contains many components that are not derived from rocks in the immediate surroundings. The gravels in the region of the Dogger Bank and Inner Well Bank Rough show analogous compositions. The occurrence of boulder clay on the sea floor points to a glacial origin of this gravel. It is held that the gravel of the Dogger Bank was brought from the west by the land-ice of the Last Glacial. The gravel of the Cleaver Bank, situated east of the Dogger Bank, shows much flint of Scandinavian origin. The latter gravel is also derived from moraines of the Weichsel (Last) Glacial. The gravel of the Texel Rough is of Scandinavian origin, but here the moraines belong to the Saale (Penultimate) Glacial. Generally, the coarsest material is found on top of the elevations in the central North Sea, whereas more and finer gravel occurs in the deeper surroundings, thus indicating selection by waves during the low sea levels of the Lower Holocene. © 1969.