Magnetic Prospecting of Diachronic Structures (Antiquity to First World War) on the Site of the Sanctuary of Ribemont-sur-Ancre (Somme, France)

International audience; The site of the sanctuary of Ribemont-sur-Ancre (Somme, France) is of major scientific interest for the knowledge of the Celtic civilization in Europe. It also presents other peculiarities: two clearly identifiable periods of occupation-the first one as early as third century BC-to the second century AD and the second one from 1914-1918. In the area disrupted through military operations, the remains of several epochs are intermingled. In order to obtain a precise knowledge of the space time organisation of each occupation, a magnetic survey was carried out. The comparison of geophysical results with the aerial photographs shot during the war allows an exact determina…