Evidence for an early land use in the Rhone delta (Mediterranean France) as recorded by late Holocene fluvial paleoenvironments (1640-100 BC)

The overall objective of this paper is to describe the late Holocene (1640-100 BC) sedimentary and biological evolution of the Rhone-delta-plain, to interpret the sedimentary facies and palynofacies as the result of the effects of fluvial dynamic fluctuations and relative sea level change and to evaluate the paleohydrological constraints in the development of the land use and settlements of the Camargue. Focus is made on the upper part of V-III core drilled on NE of the Vaccares lagoon. By combining sedimentology, palynology, magnetic susceptibility and archeological data, this study allowed to identify the superposition of three types of paleo-environments (marsh, fluvial floodplain, levee/crevasse splay). This sequence indicates a gradual extension of fluvial environments between the end of the second millennium BC and the Ist century BC. The Variability of fluvial dynamic is evident during this period with important hood events which contrast with periods of low flow. Pollen record can be a good marker of the fluvial dynamic variability. The expression of the riparian tree pollen grains in the coarser floodplain deposits could correspond to increased fluvial influence and probably to erosion of riverbank during flood events. The local plants are associated to the low energy sedimentary environments. Focuses are made on the relations between the evolution of the environment and land use. The development of the cereal culture in the floodplain of the Rhone delta has been demonstrated between 1640-1410 and 100 BC. The last alluviation of the Rhone perturbs the research of the archaeological sites in the central part of the delta but the existence of the rural villages from the first part of the first millennium BC is highly possible. (C) 2000 Editions scientifiques et medicales Elsevier SAS.