Abstract
The chronostratigraphy of Pleistocene and Holocene coastal deposits in the Médoc Peninsula (southwest France) was revised during preventive archaeology work carried out prior to the restoration of the riprap protecting L'Amélie seaside resort. This study revealed that the Pleistocene deposits were more complex than initially expected. At the base, they comprise subtidal to supratidal estuarine units (“Argiles du Gurp”: laminated silts, green clay, sandy peat with tree stumps) related to the high sea level of Marine Isotopic Stage (MIS) 11 (Holsteinian). These deposits were incised by a fluvial/deltaic channel at the end of the interglacial, then covered by aeolian sands dating back to MIS 10. The whole area is covered unconformably by gravelly sand colluvium. Holocene aeolian deposits fill a small valley cut into the Pleistocene deposits and indicate the arrival of the coastal dune massif in the area during the late Antiquity. An overview of the results obtained in Médoc shows successive bodies of estuarine deposits indicating a gradual northward migration of the Gironde estuary. Only a few high marine levels are recorded (MIS 1, MIS 9, MIS 11, Gelasian, Piacenzian), presumably both because the sea level reached was similar to or higher than the Holocene level and because the deposits were preserved from erosion during the periods of valley incision.
Published Version
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