Megalithic architectures of northern coast of Brittany: a methodological experience to study the stone elevations

Session XXXII-3. Pre and protohistoric stone architectures: comparisons of the social and technical contexts associated to their buildingInternational audienceFrom the middle of the 5th millennium BC, the first Neolithic societies on the north coast of Brittany began to build megalithic architectures. These societies also transformed and monumentalized them throughout the Middle Neolithic, some of which had become giant tumulus. Pierre Roland Giot excavated in the 50s and 60s three of the best preserved monuments: Barnenez, Carn and Guénioc (Guennoc) in Finistère. They have complete corbelled vaults conserved for 6000 years. He carried out these works according to the methodologies of the time, including the study of the internal funerary spaces and the excavation of the facades in order to only obtain a general plan.Since 2011, data regarding these buildings have been updated with a new methodology made for prehistoric elevations' study. This is the building archeology, commonly used for the study of historical periods. It has been adapted to fit the specific features of megalithism, mainly built in dry stone. This methodology makes it possible to highlight more precisely the architectural evolution of the site as well as to observe the gestures and organizations of the builders, usually unknown for Prehistory.Therefore, we studied the original and accessible elevations of the three edifices of Barnenez, Carn and Guénioc with this methodology. The results showed that these sites had a much more complex architectural evolution than it had been observed by P.-R. Giot. For each of the phases, the technological and formal data showed a real conceptualization of the architecture and builders' skills. Moreover, we have compared the data between these edifices and then with others on the north coast of Finistère. An architectural pattern emerged and raised the question of the mobility of these patterns or builders