Stability of an offset kink in the North Hinder Bank
Smith, D.B. (1988). Stability of an offset kink in the North Hinder Bank, in: de Boer, P.L. et al. (Ed.) Tide-influenced sedimentary environments and facies. Extended versions of papers presented at the Symposium on Classic Tidal Deposits, held August 1985 in Utrecht, Netherlands. pp. 65-78 In: de Boer, P.L. et al. (Ed.) (1988). Tide-influenced sedimentary environments and facies. Extended versions of papers presented at the Symposium on Classic Tidal Deposits, held August 1985 in Utrecht, Netherlands. D. Reidel Publishing: Dordrecht. ISBN 90-277-2622-1. ix, 530 pp., more |
| Abstract | The southern part of North Hinder Bank is offset from the bank's main longitudinal axis by an approximately 750 m wide kink. While both the flanks and crests of the bank are superimposed by two to four metre high sand waves several ten metre high sand waves are present in and at the opposing ends in the offset kink. A comparison of survey lines taken from available hydrographic survey charts show that North Hinder Bank has changed little in cross section form during 135 years. Magnification of the initial offset kink into an s-shaped curve accompanied by lateral displacement of the adjacent sections to the bank has not taken place. The stability of the present offset kink in Northern Hinder Bank suggests that the process of sandbank propagation through lateral displacement of an initial kink, accompanied by the formation of deep enclaves that eventually blowout, as proposed by Caston (1972), is effectively restrained when sand waves are present. Sand waves on the bank, in particular in the region of the kink, appear to restrict the movement of sand along and over the bank by acting as semi-enclosed sand storage units. Separation of a linear sandbank at an offset kink to form two adjacent banks could occur if a col was to develop between offset sections of the bank. This would however require a sustained removal of sand from the bank in the kink via the sand waves present there. The process itself could be initiated by a reduction in the quantity of sand supplied to the middle reaches of the offset kink from along the sandbank or carried to the bank from the adjacent sea floor. Under these circumstances the respective ends of the initial offset would only be slightly displaced laterally. |
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