Nouvelles données sur l’architecture et l’environnement des mégalithes grâce aux prospections géophysiques multiméthodes

This paper synthesises the results of geophysical surveys carried out between 2011 and 2016 on twelve Neolithic funerary monuments in central-western France, distributed between the Loudunais and the Ruffecois. Results obtained by these non-invasive methodsmakes it possible to address several issues. First, the elements of the internal structure of four cairns in the department of Charente (the Motte de la Jacquille and the Petite Pérotte in Fontenille, the Justice and the Vieux Breuil in Tusson) have been identified thanks to electrical resistivity maps with several depths coupled to resistivity cross-sections. A previously unknown side chamber to the dolmen of the Petite Pérotte was detected. The tumulus of the Vieux Breuil, meanwhile, appears to be composed of two highly resistant massive elements, probably corresponding to two funerary chambers. Second, resistivity surveys have revealed the state of preservation of three monuments in Charente (the Petite and the Grosse Pérotte in Fontenille, the Maison de la Vieille in Luxé) and thus allowed us to identify the most damaged areas. Third, the limits of the material spread area of six levelled monuments (in Charente: the Pérottes, in the Vienne: Chantebrault IV, V and VIII in Saint-Laon, and Briande 1 in Arçay) and the nature of these materials have been determined through magnetic or resistivity mapping. The stone cairns are thus distinguished from the earth mounds, and it is possible to estimate the initial breadth of each monument. Fourth, these methods were used to try to locate megaliths visible on ancient representations but now disappeared, such as that of Briande 1. Finally, magnetic survey were carried out on large areas around seven cairns or dolmens in order to identify possible peripheral structures (the Petit and the Gros Dognon at Tusson in Charente, Chantebrault IV and V, the Pérottes, the Motte de la Jacquille). With the exception of Chantebrault IV, signals corresponding to quarries, pits or ditches seem to be systematically located in the adjacent area. Near the Pérottes, only a curvedditch and a probable pit were mapped at the base of the two monuments. Meanwhile the vicinity of the dolmen of Chantebrault V presents signals that could correspond to several pits. Around the tumulus of the Petit and the Gros Dognon, however, it is dozens of structures that were revealed. The rocky spur on which the cairn of the Motte de la Jacquille was built is barred by seven segments of a wide disconti