Minéraux volcaniques et alpins à l’abri du Maras (Ardèche, France) : témoins de vents catabatiques dans la vallée du Rhône au Pléistocène supérieur

The new excavations at the site of Maras (Middle Palaeolithic, Ardèche) allow the identification of a thick layer (No. 4). It contains two human occupation phases (4.1 and 4.2) associated with beds of limestone fragments separated by sterile lœss. Their study shows that they contain volcanic minerals that are not concentrated in tephras levels. Nature provides evidence on their origin: green clinopyroxene, zircon, sphene (Mont-Dore), olivine (Massif Central and/or the Alps). The glaucophane is characteristic of the Alpes. The Montdorian minerals come from the last phase of activity of Sancy (392–280 ka). Their presence in the lœss dates to the end MIS 5 and beginning of MIS 4 thereby marks their secondary position. The mineralogical homogeneity implies recurrent deflation of the same source areas (Rhone Valley/Massif Central). The regular abandonment of the site by Neanderthals during the development of layer 4 would be connected with the severe climate allowing deposition of lœss.