L’habitat Néolithique final de Beau Phare à Aiguebelette-le-Lac (Savoie)

The site of Aiguebelette-le-Lac / Beau-Phare is one of two final Neolithic settlement sites on Lake Aiguebelette. It is located in the southern part of the lake, on an extension of the shore platform, which forms a small peninsula to the north of Lépin Castel. Situated in shallow water (between 0.5 and 2 m in depth), the site was first identified in 1863 and was a focus for artefact collecting until the beginning of the 20th century. Following the inclusion of the site on the Unesco list of World Heritage Sites in 2011, Y. Billaud undertook the direction of a monitoring project, which included a condition assessment and bibliographic survey of the site conducted in 2016. A review of data produced by R. Laurent (1971) and A. Marguet (1983 and 1998), coupled with a short fieldwork campaign, significantly advanced our knowledge of the site. The extent of the site was established and an entrance path, which traversed three palisades, was identified and mapped. An area of 100 m 2 at the centre of the site was surveyed, bringing the total area recorded to 230 m2. As part of the continuing exploration of the site, an underwater survey was carried out in 2018. The aim of this campaign was to plot the surviving timber piles in order to obtain an overview of the layout of the village. Prior to the recording of the piles, a 3600 m 2 grid was laid out. Depending on the area of the site and the density of piles, each 10x10 m square was subdivided into four intermediate units, each measuring 25 m 2 . Some 1401 piles were plotted within an area 2600 m2, which brings the number of recorded piles to 1670 out of a total of about 3000 for the entire site. The survey report throws considerable new light on the layout of the site. The gently curving access trackway crosses the village and extends as far as the northern extremity of the peninsula. It is formed by two parallel rows of piles, positioned some 1.6 to 2 m apart. The line of the path has been traced over a distance of about 90 m. Located to the east of the central axis of the peninsula, the trackway slopes gently upwards (0.7%) as far as the inner palisade before rising more steeply at the entrance to the village. It is formed of almost 290 piles, which are predominantly small in diameter and protrude only slightly above the sediments. The most evident entrance to the village is located on the axis of this trackway. It is formed of two rows of contiguous piles, which form a narrow bottleneck measuring less than 1 m in width. Some dendrochronological dates suggest it was built with trees felled in -2672. At least three palisades have been identified, representing several phases of building and re-building. The outer palisade forms the first enclosing element, which would have been encountered by approaching the site from the south. On the western side of the trackway, a single line of posts can be observed while to the east three roughly parallel lines are visible. The middle palisade features a marked dissymmetry between the sections to the east and west of the trackway. On the western side, it is composed of 24 piles spread out over a length of about 25 m. To the east of the trackway, its morphology is similar over a length of about 7 m : it is composed of densely spaced piles, which are medium size and very eroded. The line of the inner palisade is difficult to discern apart from an initial section at the east and a second section corresponding to the topographical “ centre” the 1998 survey. Four piles belong to trees felled in -2684. The two segments of this palisade are typologically similar to the middle palisade : they are composed of piles of various dimensions, but always quite small, which are positioned very close together (less than about 0,5 m apart). The easternmost section is interesting because it does not form a straight line but instead but appears to form a dog-leg to the south-west where we observe five aligned piles. At this point, the gap in the palisade resembles an entrance and is precisely located in the continuity of a south-west/ north-east orientated circulation area. The layout of the village is very regular with most buildings orientated perpendicularly to the axis of the pathway, particularly in the eastern sector. To the west of the access path, we can distinguish four buildings. The westernmost of these is perhaps the most easily identifiable ; the small building, measuring 4 m by 6 m and orientated east/west, is composed of relatively large piles. The roof and foundation piles, intended to support the roof ridge and sill beams, are generally over 12 cm in diameter and, based on field observations and the heights of the surviving cones, appear to be of hard wood. Located a short distance to the north-east, we observe a second similar building. Also orientated east/ west, this small building (4 x 7 m) is formed of three rows of posts ; it too is supported on relatively large piles. An enigmatic building lies in the southern part of the village, between the inner and middle palisades. Measuring about 5 by 8 m, it is directly adjacent to the pathway and the three rows of posts that delimit it are orientated north/ south. The posts located at the extremities of the three rows are paired and have a diameter of more than 14 cm. The small number of piles to support the sill beams, and the absence of posts to support the cross-pieces, suggest that this building lacked a raised floor, or indeed any type of floor, and may have been open-sided. Its dimensions, its location adjacent to the pathway and its architecture do not suggest a domestic structure. While its exact function remains unknown, we could hypothesise that it acted as an area for the storage and drying of timber, or perhaps as a workshop or warehouse. The largest building in the western sector is located at the centre of the site, facing the entrance within a space marked by a very high concentration of piles. Measuring about 5 by 10 m, this building is formed of three north-south orientated rows of piles. The eastern and western rows are formed of six groups of posts that delimit five bays. The posts are generally quite substantial (between 17 and 20 cm) and are of hardwood with very well-preserved erosion cones. At the centre of the structure, the row of posts intended to support the roof ridge is clearly identifiable, particularly in the southern part of the building where they are arranged in pairs. In contrast to the central building, the roof ridges of the other buildings in the sector are orientated perpendicular to the axis of the pathway. The buildings are thus arranged adjacent to each other with their long sides orientated east-west thereby reducing their exposure to the prevailing wind which blows down the Epine Mountain. Nine rows of piles, positioned 1.5 to 2.5 m apart, are visible and their high density probably reflects the permanence of occupation at this spot, with considerable evidence for repairs and extensions. The architectural reconstruction of these buildings is somewhat trickier. The traditional widespread model of buildings composed of three rows of weight-bearing posts would allow us to envisage three buildings measuring about 4 by 12 m. For the first time in Savoie and Haute Savoie, we have been able to obtain the partial plan of a lakeside village dating to the third millennium BCE. The extensive topographical survey covering an area of 2500 m 2 has yielded concrete evidence regarding the organization of the village and the structuring of its principal constituent planimetric elements. The unique and rich nature of the site stems from its probable short duration, which allows us to identify the general layout of the habitation areas and storage areas

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