Abstract
Between the Rhône and the Massif des Maures, geomorphological research, radiocarbon dating and archaeological excavation has revealed synchronous variations in morphological evolution produced by changes in climate. Following one or more torrential protohistoric phases, the later Iron Age and Gallo-Roman civilizations were marked by a reduction in runoff from slopes and a lowering of the water level in marshy areas. This was probably due to drier climatic fluctuations linked to a more even seasonal rainfall distribution. The early Middle Ages and the beginning of Modem Times correspond to a renewed increase in rainfall, the erosive effects of which have been exacerbated by human activity.