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Origin and history

The Dolmen de la Pierre Couvretière, located in Ancenis-Saint-Géréon in Loire-Atlantique, is a megalithic monument of the Bronze Age, classified as historical monuments in 1926. It stands out as the only dolmen still visible in the Pays d'Ancenis, originally laid on the banks of the Loire River, now enclaved in an industrial area. Its architecture, typical of corridor dolmens, includes a conglomerate cover table, two sandstone orthostats and a gneiss pillar, the latter suggesting a multi-kilometre transport of materials.

Archaeological excavations conducted in 1972 by Jean L'Helgouach and in 1973 by Daniel Prigent revealed a rich funerary material: 76 flint tools, 70 campaniform pottery tins, metal objects (gold and copper), as well as human bones and animals dated between 2880 and 2990 BP. These findings attest to the re-use of the site by local populations, linked to neighbouring habitats in the Loire riverbed. The dolmen, partially destroyed to serve as a quarry, preserves traces of its original tumulus, now almost disappeared.

According to a local legend, the dolmen is linked to a pact between God and Satan: the latter, loaded with three stones, would have abandoned his burden by hearing the cock's song, giving birth to the alternative name Peter of the Devil. The site, threatened by urbanization in the 1960s, was preserved in situ after clean-up and excavation campaigns. Despite efforts to develop (teaching panels in the 1980s), it remains vulnerable, a fragile witness to a regional megalithic heritage.

The cover table, inclined to 45° and partially immersed, is the only part visible today. Orthostats, one of which has an artificial cupula, and remnants of the tumulus (calcareous stones) reveal an initially more imposing structure. Exhumed bones, including 4 skulls and remains of at least 10 individuals, as well as animals (beefs, pigs, wild cat), shed light on funeral practices and the lifestyle of the populations of the Bronze Age on the Loire River.

Dolmen also illustrates the conservation challenges of archaeological sites in urban areas. Its ranking in 1926 and excavations of the 1970s documented its history, but its environment continues to deteriorate. The objects discovered, like a gold plate and a copper scissor, underline its cultural importance, while its legend recalls the popular imagination associated with megaliths.

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