A Late Holocene case study from south-west France: Combining geomorphology and geophysics to understand archaeological site morphology

This article combining geophysics and archaeology aims to provide a more comprehensive characterization of the La Ruchelle valley located in the south of the Celtic site of La Peyrouse (Saint-Félix-de-Villadeix, Dordogne, France) (occupied between the 3rd century BC and the 2nd century AD) through geological prospection (core sampling, geotechnical prospection and mechanical prospection) and near-surface geophysics (electrical resistivity tomography). On this site, other studies have been carried out since the discovery of the site, such as magnetic prospecting and a hydrogeological study. Geophysical data coupled with geological prospection were used to understand the geology of the valley: (1) The bottom of the valley is filled with colluvium with a thickness of 6 m maximum; (2) part of the colluvium filling characterize by a very low resistivity is indeed archaeological remains; (3) three very distinct geological horizons have been detected—two of these horizons are characteristic of Campanian limestone (C6d and C6e), and the last consists of colluvium with a filling between 2 and 6 m in the centre of the valley, which is particularly thick. This last very thick formation is in fact filled with archaeological and prehistoric remains.