Tectonic, eustatic and climatic significance of raised beaches of Val de Saire, Cotentin, Normandy, France
Résumé
Detailed mapping, morphostratigraphical and geochronological analyses were undertaken in the Val de Saire, Cotentin, Normandy, northern France. These studies have identified a series of Middle and Upper Pleistocene-age deposits overlying four wave-cut platforms (PF IV–PF I), which can be associated with temperate high sea-level events and equated with MIS 11, 9, 7 and MI Substage 5e. A sea-level stand recorded at –20 m NGF at the La Mondrée site seems to correspond to MI Substage 5c or 5a. The completeness of the Val de Saire record, and particularly the width of platform IV (MIS 11), has so far no equivalent on the south coast of the English Channel. This study provides contribution to an understanding of the impact of the interglacial–glacial cycles in a coastal intraplate situation. The cyclicity of the morphogenesis is explained by interaction between eustatic variations and strongly expressed activity of slow uplift (ca 60 mm/kyr through the Middle Pleistocene). Several OSL dates from the gravel to sand sequence of the Eemian–Weichselian cycle indicate that these deposits represent the marine regression of the end of the Last Interglacial.