The flora and fauna of late Pleistocene deposits on the Cotentin Peninsula, Normandy

Abstract

The transition from late interglacial (temperate) to early glacial (cold) stage environments, involving not only climatic deterioration, but also a fall in sea level, has been rarely described. The Cotentin Peninsula, Normandy, lies beyond Pleistocene ice limits, and hence has less stratigraphic complexity than areas characterized by ice advances and retreats. Furthermore, it possesses a number of closely spaced coastal sites where late interglacial to early glacial organomineral sediments are present. These sediments overlie interglacial raised beach deposits, or more ancient wavecut rock platforms, and are succeeded by periglacial (head and loess) deposits. These localities thus afforded an ideal opportunity for detailed multidisciplinary studies of sea level and terrestrial environmental change. Investigation of the geomorphology and stratigraphy was accompanied by palaeobotanical and palaeoentomological analysis of the organomineral deposits. The fossil evidence shows that as sea level fell from a height similar to the present day, the climate cooled from temperate to arctic, and that these changes were accompanied by major modifications in the flora and fauna. Previous stratigraphic, pedological and palynological studies of the sites have been taken to imply multiple environmental changes, with ages ranging from Elsterian to Weichselian. The research described here, together with radiometric age determinations, implies that the raised beach and organomineral sediments were associated with a single marine regression between ca . 121 and 45 ka, that is, late in the Eemian Interglacial and early in the Weichselian Glacial stage. These environmental changes are discussed with reference to those recorded at sites in France and Britain that probably date from the same period.