dAf 90
LOCHT Jean-Luc (éd.)
Bettencourt-Saint-Ouen (Somme)
Cinq occupations paléolithiques au début de la dernière glaciation
Situated in the North of France, Bettencourt-Saint-Ouen is an open-air Middle Palaeolithic site, most probably used as a hunters' stopping place. Five successive phases of occupation have been excavated, covering a period of 40,000 years. Study of the site has revealed fundamental data for our understanding of human occupation, as well as important information’s on environmental changes to the site during the final glacial period (from the Eemian Interglacial to the lower Weichselian Pleniglacial). Distribution of finds at Bettencourt, coupled with the technology and typology of the site's lithic industries, point to a continuity in systems of production and cultural traditions from 112,000 to 68,000 BP.
Abstract
Abstract
The site of Bettencourt-Saint-Ouen is situated in the basin of the Somme River in the western part of the large European loessic zone. It is located in a dry valley whose morphology, typical of this basin, is characterised by the opposition of an abrupt chalk slope facing west-northwest and a gentle silt slope facing east. This topography is favourable for the recording of a well developed silt sequence and for the deep conservation of prehistoric levels. The excavation lasted S months, from the 20th of February to 15th of July 1995. The site is divided into three independent sectors separated by small fossilised erosion valleys that have carved the Early Weichselian humic soils. A surface area of 866 m2 was excavated.
The study of the stratigraphy, sedimentology and paleopedology of the Bettencourt sequence, coupled with a palynological analysis and a series of TL-IRSL datings of the sediment and ESR-UfTh datings of teeth has revealed a complex pedostratigraphical sequence which integrates a unique succession of five Palaeolithic levels (N3b, N3a, N2b, N2a-et N1) during the beginning of the Early Weichselian, a complex transition period between the end of the Eemian Interglacial and the lower Weichselian Pleniglacial, Le. between 112 000 BP and 68 000 BP.
Stratigraphically, the oldest of the five Palaeolithic levels (N3b) is contemporary with the beginning of the climatic degradation following the Eemian (Herning stadial). To our knowledge, it is the only occupation found in situ on an open-air site in the north of France that is contemporary with the oxygen-isotope stage 5d. A variety of technical production systems coexist in the lithic industry (Levallois, discoidal and laminar). Within each of these production systems, a large technical flexibility is observered. This techno-typological composition seems to be quite original in the Middle Palaeolithic of the Early Weichselian period. The analysis of the spatial distribution of the artefacts and of the refittings demonstrates a local production of the blanks.
Contemporary with the stabilisation of the environment and the development of a first grey forest soil, beginning around 105 kya with the Brorup interstadial, the N3a lever is represented only by a little flint knapping station and about forty artefacts. An almost complete refitted block demonstrates a laminar production using a direct bidirectional operating mode.
After a new climatic degradation, during the Rederstall stadial (5b) around 85 kya, the levels N2a and N2b are integrated in a sequence of colluvial deposits in which a second grey forest soil developed under environ mental conditions close to those which prevailed at the end of the filling-in of the depression. This phase of the forest steppe is contemporary to the interstadial dominated by a continental temperate climate with strong seasonal freezing, and which can be correlated with the Odderade interstadial (5a), approximately between 75 kya and 8S kya.
The main level (N2b) is the richest and most dense. It is omnipresent in the three sectors of the excavation. Situated at the base of the grey forest soil, it is attributed to the oxygen isotope stage 5a. There is no stratigraphic correlation between the three zones of the excavation, the contemporaneity of sectors 1 and 2 on the one hand, and of sector 3 on the other hand, is probable, but not certain.
If the material coming from each of the three zones is compared, sector 3 is different to the two others, which appear to be quite similar in technological and typological composition. In sectors 1 and 2, the main core reduction sequences (chaînes opératoires) are Levallois, particularly the laminar debitage that is expressed following quite varied production modes. In sector 3, the knapping activities lead principally to the production of blades and points using the unidirectional convergent Levallois method.
The presence of bone remains in the Middle Palaeolithic open-air sites of Western Europe is very rare in a loess context. At Bettencourt two species are present: the horse and the aurochs. Their presence indicates an open continental environment at the beginning of the oxygen-isotope stage 5a. Found in sector 3, in an identical stratigraphical position to that of lever N2b, these remains are associated with an original lithic industry with blades, points and flakes produced using a variety of production systems. The relationship between these lithic production systems and the use of the industry on large fauna has been studied by microwear analysis.
This study has demonstrated significant work on wood and enabled the identification of numerous marks of butchery, for which the Levallois points were produced. In sector 2, and principally in sector 3, these activities seem to be located at the periphery of the debitage concentrations and indicate areas of specific activities, sometimes in the zones which do not contain many lithic artefacts. These zones and debitage concentrations are related using the refittings, which have demonstrated the removal of artefacts from the knapping stations to the peripheral zones. Taken as a whole, these observations give us a glimpse of the coherent structuring of a Middle Palaeolithic hunters' stopping place.
The geological data show that the N2a lever is contemporary with the oxygen-isotope stage 5a. It was only possible to identify it on a few square metres of sector 3. The small amount of materiel which it contains is identical to that of level N2b, principally points and blades produced using the unidirectional convergent method, a technological profile similar to that of level N2b. Finally, the last occupation of the site, the N1 level, was found in an isohumic soil of steppe type corresponding to the first of the three steppe soils of the stratotype of Saint-Sauflieu (SS2; oxygen-isotope stage Sa), which calls to mind an open, cold and dry environment. From a chronological point of view, these soils mark the end of the Early Weichselian and are dated between 72,000 and 68,000 BP. The lithic industry shows a number of production sequences (blades, points and flakes) and does not differ fundamentally from that of previous occupations.
From a palaeoenvironmental standpoint, the site of Bettencourt-saint-Ouen provides fundamental data for our understanding of the Early Weichselian period. The lithic industries show a durability in the different production systems for almost 40,000 years. This observation demonstrates the weight of cultural traditions confronted with environ mental changes
