Middle and Late Pleistocene evolution of the Ardèche Valley archaeological landscapes (France)

Most archaeological and palaeo-environmental archives are preserved in specific environments (buried sediments, rock shelters, cave environments). Hence, the information we can obtain is usually incomplete, and lacking spatial and morphological significance. Studying landscape evolution can help us to understand the location and distribution of past societies and their relation to Quaternary environments. In the Ardèche Valley, most Middle and Late Palaeolithic sites are preserved in caves and rock-shelters and in rare cases in fluvial sediments. Here we apply an integrated geomorphological approach to the study of the evolution of the Ardèche Valley combining multi-method dating, geomorphological mapping and surveys of cave and fluvial formations. We review chronological results obtained through multi-method dating (electron spin resonance (ESR), infrared stimulated luminescence (IRSL), uranium-series (U-series), combined electron spin resonance/uranium-series (ESR/U-series)) on cave and riverine objects and combine them with topographic and stratigraphic observations in an integrated Bayesian hierarchical model. The results are in agreement with those obtained from other rivers in mountainous environment around the Mediterranean Sea and show sedimentation/incision phases that match the 100 ka glacial/interglacial cycles. The mean rate of river incision deduced from the established chronology for the Middle and Late Pleistocene period, 76 ± 7 m.Ma−1, shows adjustments to a moderate uplifting dynamic that shaped the main topographical features seen today in the landscape of the Ardèche Gorge. The spatially reconstructed alluvial features provide a palaeogeographic framework that can be used directly as a chronological and topographical constraint for archaeological research in the Ardèche catchment.