Erosion and transport processes on badlands slopes in Baronnies Moontains (French Southern Alps)

Abstract

Badilnds slopes are frequent in Baronnies Mountains. Previous observations with the purpose of selecting study areas for measurements of slope evolution have shown the following process interaction: marls are broken up by frost action in winter and alternate wetting and drying in summer. Little fragments of desintegrated marls are transported on steep slopes by debris falls and grain flows when ice thaws with possible wind action, and by splash erosion during showers. Marly debris accumulate downslope and form a thick cover in which seeped waters generate pipe flow. Now and then, the roof of a pipe breaks down and from the pipe outlet occurs a mud-flow which carries away marly debrias in the talweg. This process brings about instability of the downslope cover of marly debris and generates debris slides, so that fresh marls are again exposed to weathering. As a consequence of these processes, slopes retreat, but is it a downwearing or a backwearing? Happens bedrock erosion in talweg? Field measurements will give answers to these questions.