Le Pléistocène de la façade atlantique du Nord-Médoc (France) : état des connaissances sur la lithologie et la chronostratigraphie des « Argiles du Gurp » s.l [The Pleistocene of the atlantic side of the north-Medoc (France) : progress achieved with respect to the lithology and chronostratigraphy of the « Argiles du Gurp » s. 1.

Abstract

The Pleistocene outcrops of the erosional cliffs of the North-Médoc coastline have been described since the last century as «Argiles du Gurp». They constitute two sedimentary sequences separated by a level of lignite older than 50000 years BP. The lower sequence has a lagoonal origin and the upper is continental. A synthesis of previous works and new field investigations allow us to detail the sequence lithology and to propose a new nomenclature and a palaeogeographical meaning for these deposits. The upper part of the lower sequence includes evidence of a former raised sea level near the present day one which could be attributed to the Eemian or Holsteinian interglacial. The upper continental sequence has a fluvial origin which could be contemporeneous with a glacial period. The entire outcrops was eroded and cryoturbated during the Würm IV glacial maximum and covered by the coastal transgressive dune systems during the Holocene.