Holocene development of the east bank of the Gironde Estuary: geoarchaeological investigation of the Saint Ciers-sur-Gironde marsh
Mellallieu, S.J.; Massé, L.; Coquillas, D.; Alfonso, S.; Tastet, J.-P. (2000). Holocene development of the east bank of the Gironde Estuary: geoarchaeological investigation of the Saint Ciers-sur-Gironde marsh, in: Pye, K. et al. Coastal and estuarine environments: sedimentology, geomorphology and geoarchaeology. Geological Society Special Publication, 175: pp. 317-341. https://dx.doi.org/10.1144/GSL.SP.2000.175.01.23 In: Pye, K.; Allen, J.R.L. (Ed.) (2000). Coastal and estuarine environments: Sedimentology, geomorphology and geoarchaeology. Geological Society Special Publication, 175. The Geological Society: London. ISBN 1-86239-070-3; e-ISBN 9781862394230. 435 pp. https://dx.doi.org/10.1144/GSL.SP.2000.175, more In: Hartley, A.J. et al. (Ed.) Geological Society Special Publication. Geological Society of London: Oxford; London; Edinburgh; Boston, Mass.; Carlton, Vic.. ISSN 0305-8719; e-ISSN 2041-4927, more |
| Keywords | Marine/Coastal; Brackish water; Fresh water |
| Authors | | Top | - Mellallieu, S.J.
- Massé, L.
- Coquillas, D.
| | |
| Abstract | The nature of postglacial sea-Ievel change and sediment infilling of the Gironde Estuary, SW France, has previously been reconstructed using a sequence stratigraphic model. This paper examines specifically the development of the St Ciers-sur-Gironde marsh during the late Holocene. The study area forms the largest expanse of coastal wetlands on the east bank of the Gironde. A geoarchaeological approach is used incorporating borehole survey, sedimentological and diatom analysis, radiocarbon dating, archaeological, documentary and cartographic evidence, which aims to test and refine the previous model of estuarine development. The later Holocene sequence is characterized by alternating clay-silt and peat facies. Diatom evidence indicates that clay-silt units represent sedimentation under marine-brackish estuarine conditions in intertidal mudflat, and potentially saltmarsh, environments. The palaeo-environmental conditions represented by the main upper peat unit, dated to 5600-2600 BP, are currently unknown due to the absence of diatom evidence from these levels. Within an overlying trend of rising relative sea-Ievel over the past 6000 years, 3 negative sea-Ievel tendencies appear to have occurred. There is insufficient resolution in the present data set to determine the exact nature of each or their duration. |
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