Bedforms on the Middelkerke Bank, Southern North Sea

  1. B. W. Flemming and
  2. A. Bartholomä
  1. J. Lanckneus and
  2. G. de Moor

Published Online: 14 APR 2009

DOI: 10.1002/9781444304138.ch3

Tidal Signatures in Modern and Ancient Sediments

Tidal Signatures in Modern and Ancient Sediments

How to Cite

Lanckneus, J. and de Moor, G. (1995) Bedforms on the Middelkerke Bank, Southern North Sea, in Tidal Signatures in Modern and Ancient Sediments (eds B. W. Flemming and A. Bartholomä), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304138.ch3

Author Information

  1. Marine and Coastal Geomorphology Research Unit, Geological Institute, University of Gent, Krijgslaan 281, B-9000 Gent, Belgium

Publication History

  1. Published Online: 14 APR 2009
  2. Published Print: 11 AUG 1995

ISBN Information

Print ISBN: 9780865429789

Online ISBN: 9781444304138



  • large dunes, covering flanks and summit of Middelkerke Bank;
  • geographical distribution and characteristics of bedforms;
  • residual morpho-dynamic behaviour;
  • sonograms, determining dune orientation;
  • Syledis UHF-radio positioning system;
  • sonograms of November 1989, showing similar migration


Large dunes cover the flanks and summit of the Middelkerke Bank. They have constant orientation, heights ranging from 0.5 to 5 m, wavelengths of 75 to 150 m and in most cases asymmetrical profiles. No relationships could be established between the heights of the large dunes and the grain sizes of the sediment or the water depth in which they are developed. The slopes of both lee and stoss flanks are very low. Almost every large dune on the bank can assume both ebb and flood orientations through time. Two cases are presented in which particular swell and wind conditions induced common orientations to nearly all the large dunes. No significant migration was observed for six large dunes on the northern end of the bank over a time span of 13 months during which five surveys were carried out. Fields of small and medium dunes occur on the whole bank and in the adjacent swales. They are two-dimensional and have wavelengths ranging from 1 to 15 m. They are oriented at an oblique angle to the large dunes with a counter-clockwise offset of approximately 20°, their alignment being perpendicular to the direction of the peak tidal currents. Flood- and ebb-oriented small dunes cover the western and eastern flanks of the bank respectively. The boundary line between the dune fields having opposing asymmetries more or less follows the axis of the bank and often coincides with the crest lines of the larger dunes.