Abstract

The construction of a bathymetric map of the continental shelf of the British Isles around Orkney and Shetland and extending east to the Norwegian Trench and as farsouth as Aberdeen is described. The map is based on echo traces made by a large number of ships in the course of their duties and also on all available published charts and much unpublished bathymetric data. The map is presented together with maps showing the nature of the bottom and the roughness of the bottom based on information obtained during the construction of the bathymetric map.

The origins of the various features appearing in the maps are discussed. It is shown that in the Orkney and Shetland area broad flat bottomed deeps coincide with basins of young sediments (post-Devonian and probably Mesozoic or Tertiary) and are probably of glacial origin. In the North Sea deeps are mostly very narrow and elongate and these have been interpreted as tunnel-valleys formed beneath an ice front. They are arranged in an arcuate belt partly surrounding the deepest part of the North Sea where there is a patch of mud. This mud was probably deposited from the water flowing out from beneath the ice where it was formed into a lake. It is possible that a submarine canyon on the edge of the Norwegian Trench to the east of the mud patch is the overflow channel for this water.

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