Before the spatial analysis of Beg-er-Vil: A journey through the multiple archaeological dimensions of a Mesolithic dwelling in Atlantic France

The Beg-er-Vil coastal site (Quiberon, Morbihan, France), initially excavated in the 1980s, and more extensively since 2012, is exposed to strong marine and anthropic erosion. At the present time, the main challenge is to define the status of the site by describing its formation dynamics. This necessitates investigating the taphonomic and erosive mechanisms using a combined method adapted to the shell midden levels, before undertaking spatial analysis. The archaeological level is protected by a thick dune and is subdivided into several stratigraphic units (SU), which record several changes in the function of the site. It is made up of accumulations of shell pockets covered in sandy sediments. The micromorphological analysis shows that this waste area seems to develop into an area of activities and movement. These surfaces also record alternating dry and wet seasonal conditions, but with no phase of abandonment. Systematic pH measurements show variations of 7.7 to 9.0 depending on the layers, corresponding to a slightly alkaline to alkaline acid-basic status. The mapping of measurements can be correlated to structures and archaeological remains of organic origin. The excavation shows that the division of the dwelling area was guided by topographic factors, with a circular dwelling 3.50 m in diameter installed on a flat zone and a shell waste zone on a slope towards the sea. Numerous fire-related activities were also carried out in this zone (pits, hearths). Spatial analysis by GIS shows a high concentration of recorded objects (lithics, bones, shells) to the west of the excavated area, in the shell level. Marine erosion is the main erosive factor limiting our knowledge of the site. The distance to the coastline was estimated after reconstruction of the relative sea level during the Holocene using the “Sea-Level Index Points” (SLIPs) methodology. Three SLIPs indicate a relative sea-level position between − 15.5 m and − 11 m and a foreshore area at a depth between − 7.15 and − 14.02 m around 6200 BCE. This paleogeographic reconstruction approach indicates that the site of Beg-er-Vil was located a few hundred to a few kilometres from the coastline.