Techno-economic and functional approach of the recent Middle Paleolithic outdoor occupation around Bayonne (Pyrenees-Atlantigues)

Over the past eight years, excavations performed by INRAP teams outside Bayonne (Pyrenees-Atlantiques, France) have updated our understanding of the Palaeolithic occupation of the Saint-Pierre-d'Irube plateau. The excavation of two open-air sites, Jupiter and Le Prisse, accompanied by test trenches and luminescence dating, have yielded a new understanding of the evolution of the landscape from the late Middle Palaeolithic. Several occupations dating to MIS 3 indicate that the plateau was heavily utilized during that period. The proximity of an abundant and high quality flint, from the Ibarbide source, probably played a role in the area's attraction for Palaeolithic peoples. Optically stimulated luminescence was used to date the late Middle Palaeolithic occupations at Jupiter to between 50 +/- 3 and 34 +/- 3 ky BP. The dating at Le Prisse is still underway. Thus far, an artefact originating from the Upper Palaeolithic layers was dated via thermoluminescence to 44.3 +/- 3 ky BP. It is thought that this artefact could have moved up from the Middle Palaeolithic layers but this conclusion awaits other TL samples currently being dated. However, these dates provide a preliminary time range for the late Middle Palaeolithic occupation of the plateau between 45 and 50 ky BP. This new chronological and stratigraphic framework has allowed the reevaluation of several older collections and surface finds in an attempt to characterize more precisely the use of the Saint-Pierre d'Irube plateau during the late Middle Palaeolithic. This work has focused on Baste, an open-air site excavated by C. Chauchat and C. Thibault in the late 1960s. Stratigraphic sequences from INRAP's recent excavations and test trenches were compiled to create a schematic section of a north-south profile for the plateau. This makes it possible to propose stratigraphic correlations between level 4 at Baste to the late Middle Palaeolithic occupations of Le Prisse and Jupiter. We thus identify a relative contemporaneity between these three occupations. The spatial distribution of lithics at Le Prisse is non-random and the refitted lithics are concentrated in the site's two high-density lithic clusters. This spatial patterning can he largely explained by anthropogenic activities, specifically the location of knapping events that produced the high-density clusters and use of flakes and tools in adjacent areas. Retouched flakes, bifaces and flake cleavers, and lithics with evidence for use-wear are over-represented in the medium and low density parts of the site, probably abandoned at their place of use. A similar spatial organization was found at Jupiter. The spatial patterning of artefacts at Baste is much more difficult to interpret due to the small area of excavation (16 m(2) compared to hundreds of square metres at Le Prisse and Jupiter). The presence of refitted lithics may indicate relatively good spatial preservation. The lithic assemblages from Le Prisse and Jupiter are both characterized by the Discoid method and low proportions of retouched tools. The cores are represented by a hierarchical unifacial structure, or less frequently, a bipyramidal structure, but are always directed towards the production of pseudo-Levallois points, accompanied by debordant flakes and other core trimming flakes. Flakes from the main part of the reduction sequence are under-represented in the refitted sample and were thus probably exported off-site. In contrast, large bifacial pieces, namely handaxes and flake cleavers. were not produced on-site but were imported and abandoned. Retouched flake tools are rare (about 3% of the assemblage) but mostly occur on large cortical flakes. These two occupations are interpreted as flake production sites where secondary activities compatible with butchery (based on use-wear analysis) were performed at the periphery of the lithic clusters. The assemblage from Baste presents a different picture. Cores with indications of the Discoid method are rare. The majority of flakes were the result of the manufacture of bifacial tools. The bifacial shaping flakes can be attributed to different stages in biface manufacture according to their size. Large flakes, with full or partial cortex, are present, along with small flakes that correspond to phases of sharpening or resharpening. The flakes are accompanied by 17 bifaces at different stages of reduction. Retouched flake tools are more abundant and diverse than at Le Prisse or Jupiter (12% of the assemblage). This occupation is focused on the production of bifacial tools for exportation and for use on-site (evidence for re-sharpening is present). The higher diversity of tools at Baste suggests that a higher diversity of activities may have occurred there as well. The Saint-Pierre-d'Irube plateau was therefore the setting for economically different and complementary occupations during the late Middle Palaeolithic. The area would have had several attractive features for Neanderthal groups, especially its proximity to the Atlantic Ocean, the nearby confluence of two major rivers, the Nive and the Adour, and the abundant and high-quality local flint. Furthermore, occupation of the area was not limited to the Saint-Pierre-d'Irube plateau: further south on the opposite bank of the Nive River, a surface collection, the Lestaulan, contains technological elements similar to Le Prisse. Cores tend however to occur on flakes, rather than nodules as at Le Prisse, probably as a result of the greater distance from the flint source. The remaining archaeological potential of the area around Bayonne is increasingly threatened by rapid urbanization. Therefore, these recent archaeological excavations, and their incorporation with a study of old collections, is particularly timely in light of this destruction of cultural heritage.