Architectural study of an Iron Age rampart undergoing destruction: Guennoc Island, Landéda (Finistère, France)

International audience; New archaeological studies have been achieved on the insular site of Guennoc. They take place half a century after those made by P.-R. Giot. This island, which has an important surface, has been fortified with a rampart whose remains are conserved over nearly 100 m. Through a study of unpublished archive data and a new fieldwork investigations, it was possible to specify the nature of this important rampart built at the end of the second Iron Age. Forced by natural erosion, the results of this non-intrusive survey constitute new elements toward an atypical fortification that could be qualified as a ‘barred island’. Results presented here report on this little-known site of rich archaeological potential that find comparison with other islands from the Atlantic coast of France.