Reconstruction of Middle Pleistocene palaeoenvironments based on pollen and stable isotope investigations at Val-de-Lans, Isère, France

In the Vercors uplands, south-west of Grenoble, the Val-de-Lans syncline is filled with thick lacustrine and glacio-lacustrine Pleistocene deposits. Artifacts discovered on its surface indicate an age older than the last glaciation. Pollen analytical investigations of five sediment sequences, including lake marls, has enabled the reconstruction of the interglacial vegetation cycle (La Côte Interglacial) which, taking into account the rôle played by Abies and a Pterocarya expansion towards the end of the interglacial, may be correlated with the Holsteinian Interglacial. At the site Lolette, this interglacial is followed by two short stadials which alternate with interstadials characterised by Picea forests. Oxygen isotope studies, including δ18O investigations, provide additional evidence for climate changes during the interglacial