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Origin and history

The dolmen of Bilgroix Point, located in Arzon, Morbihan, is in fact a covered alley dated from the Prehistory, specifically from the Middle and Recent Neolithic according to radiocarbon dating. This megalithic monument was built on the northwest side of Bilgroix Point, 14 metres above sea level. It consists of a cairn in the shape of a horse-drawn iron 17 meters long, surrounded by walls of dry stone trimming, and a 14 meters long funeral chamber, whose height under slab did not exceed 1.60 meters. The materials used, mainly leucogranite extracted on site, and the double-walled structure reflect sophisticated architectural techniques for the time.

The site was first mentioned in 1866 by G. de Closmadeuc, then president of the Morbihan Polymathic Society, which organized summary excavations. Initial discoveries, considered insignificant, include pottery and flint. In 1912, Zacharie Le Rouzic reported partial destruction of the monument by a local owner during a clearing, revealing a large amount of pottery. In 1961, road works and water supply brought to light a small archaeological furniture (potteries, flint). Threatened by the tourist boom of the 1970s, the site was saved by its classification to historical monuments in 1978. Between 1989 and 1993, Joël Lecornec carried out extensive excavations, revealing nearly 28,700 fragments of ceramics, flint tools (including blades from the Grand Pressigny), and ornament elements.

The excavations also revealed an adjacent grave south of the cairn, bounded by stone walls, as well as a dry stone structure in the shape of "S", whose function remains unknown. The archaeological furniture, preserved by the Polymathic Society, comprises two groups of ceramics (hemispherical and cylindrical/conical vessels), quartz drills, and dolerite axes. Four radiocarbon datings place the use of the site between the Middle Neolithic and the recent Neolithic, combining ceramics with an Armoric facade of the S.O.M. (Southwest of the Armorian Massif). The absence of a separate chamber in the covered driveway suggests a collective funeral use, typical of Breton Neolithic societies.

The progressive deterioration of the monument, due to human activities (dissemination, modern works) and its abandonment as a dump site in the 1970s, required urgent protection measures. Its classification in 1978 allowed the remaining remains to be preserved, although the cairn was partially damaged in 1912, reducing its initial height from 3 to 4 meters. The excavations of Lecornec confirmed the importance of the site to understand the funeral and artisanal practices of Neolithic in Brittany, thanks in particular to the diversity of lithic furniture (silex of the Grand Pressigny, dolerite) and ceramic, reflecting regional exchanges and advanced technical mastery.

Bilgroix covered walkway is distinguished by its elongated corridor architecture, without clear separation between corridor and bedroom, and its partly paved floor. The presence of a dormant millstone, a re-used broken stele, and a fireplace containing dated coals underscores the complexity of the activities on the site, combining funeral functions, craftsmanship (polishing, flint size), and possibly ritual. Today, the monument, owned by the municipality of Arzon, remains a key testimony of Breton megalithism, illustrating the evolution of the social and technical practices of the Neolithic communities of the region.

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