Age limits on the Late Quaternary evolution of the upper Loire River

Abstract

The Loire River is one of the largest rivers in Europe, draining a basin area of southern France which exceeds 100,000 km 2. Despite its significance, the Loire remains poorly studied and has a very limited amount of chronological control on the deposited sedimentary record of fluvial activity. These factors, coupled with the availability of a set of 10 radiocarbon dates on younger (c., <5 ka) Loire terraces, have encouraged us to commence an intensive programme of optical dating on terraces from the upper Loire. We have obtained relatively good agreement between single-aliquot regeneration (SAR)-based age estimates and AMS dates, and have extended the chronology of the terraces back into the middle Weichselian. Our data indicate that the key shift in fluvial style from a braided gravel-bedded system through to a sand and silt dominated system occurred at around the time of the Pleistocene–Holocene transition.