A large ancient sanctuary was discovered during preventive excavations at Magny-Cours (Nièvre). More than the cultural complex itself, the main interest of the site was the discovery of several peat bogs in which organic items (ex-voto, scraps of wood) were preserved. A multidisciplinary approach was used to understand the nature of these remains and their relation with the neighboring cultual structures. In this way, the archaeological study was completed by a series of geomorphological and palaeoenvironmental analyses, more specifically in the fields of dendrology, carpology, palynology, and the geology of sediments. Traduction : Margaret & Jean-louis CADOUX.