Berms on an intertidal shoal: shape and internal structure
Boersma, J.R.; Terwindt, J.H.J. (1981). Berms on an intertidal shoal: shape and internal structure, in: Nio, S.D. et al. Holocene marine sedimentation in the North Sea basin. Special Publication of the International Association of Sedimentologists, 5: pp. 39-49. https://dx.doi.org/10.1002/9781444303759.ch3 In: Nio, S.D.; Shuttenhelm, R.T.E.; van Weering, Tj.C.E. (Ed.) (1981). Holocene marine sedimentation in the North Sea basin. Special Publication of the International Association of Sedimentologists, 5. Blackwell: Oxford. ISBN 0-632-00858-X. 515 pp. https://dx.doi.org/10.1002/9781444303759, more In: Special Publication of the International Association of Sedimentologists. Blackwell: Oxford. ISSN 0141-3600; e-ISSN 2054-6610, more |
| Keywords | Marine/Coastal; Brackish water |
| Authors | | Top | - Boersma, J.R.
- Terwindt, J.H.J.
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| Abstract | On the intertidal part of the Ossenisse shoal, Westerschelde estuary, the Netherlands, elevated ridges or strips (berms) appear which separate areas with different bedform configuration and hydrographic character. The ebb is the dominant tide on one side of the berm; the flood on the other. Ebb and flood currents make an appreciable angle with each other and supply material to the berm which gives rise to its elevated position. The different morphological appearances of berms, varying between a high and sharp negative step and a narrow dome-like elevation, are associated with specific internal structures, in which cross-bedding and cross-lamination participate in a way slightly different from ordinary sandwaves or dunes. Spring- and neap-tides can be distinguished in the typical berm structures by juxta- or superposition of cross-bedded or cross-laminated bundles sets and cosets. Often the cross-bedding rests on sloping faces. Berms are expected to have a relatively high preservation potential. |
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