Late Pleistocene and Holocene history of the northern North Sea, based on acoustic reflection records
In: Netherlands Journal of Sea Research. Netherlands Institute for Sea Research (NIOZ): Groningen; Den Burg. ISSN 0077-7579; e-ISSN 1873-1406, more
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| Abstract |
Subbottom profiles of the northern North Sea show the presence of several Late Pleistocene and Holocene deposits, the thicknesses of which were mapped. These deposits reflect the occurrence of several glacial and interglacial stages. Buried channels show incisions of possibly Elsterian and Saalian age and deposits of the Holsteinian and the Eemian-Weichselian periods with high sea levels. North of 57°30'N a Saalian or older glacial drift and morainic ridges are present. Here glacial and glaciomarine Hills Deposits represent the advance and retreat of a Weichselian glacier, followed by the Late Weichselian maximum glaciation. At that time the North Sea temporarily became an inland sea or proglacial lake, and the Fladen Deposits were formed. Subglacial tunnel valleys and proglacial channels transported sediments into the Fladen Ground area. The British and Scandinavian ice did not meet in the central North Sea. After a minimum relative sea level of 109 to 114 m below the present had been reached at the Witch Ground, a transgression started the deposition of the Witch Deposits in the north, and subsequently the Upper Channel Fill and the East Bank Deposit of the shallower regions in the south. Directly north of the Dogger Bank tidal sand ridges were formed. At the Fladen and Witch grounds pockmarks and zones of sound-scattering were found which are probably due to gas, ascending from underlying strata. |
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