[en] Lithic and faunal remains are often the main evidence of Palaeolithic occupations and can occur on sites in highly variable proportions. The variety of remains and their relative proportions provide the best means for elucidating activities carried out on-site as well as for characterizing site function. However, numerous sedimentary processes can sort remains, including turbulent flow that can occur in different contexts (e.g., fluvial episodes, runoff in channels). While numerous experiments have explored the consequences of such phenomena in archaeological contexts, few have been carried out using both faunal and lithic remains, meaning that the relative impact of turbulent flows on these two artefact types remains difficult to characterize. Moreover, most previous experiments involved complete, sometimes still articulated bones. This important limitation makes it difficult to compare experimental analyses with data obtained from Palaeolithic archaeological contexts, where most bones are fractured as part of subsistence activities or fragmented by natural processes after discard (e.g., trampling, freezing). Consequently, it is difficult to quantify the differential transport of remains according to type. Here, we present the results of experiments designed to test the differential mobility of the two main artefact types found on Palaeolithic sites – flint and bone – in a context of turbulent flow. For this study, an experimental corridor was installed outdoors, on private land in the commune of Lamothe-Fénelon, in the Lot département of southwestern France. The corridor's substrate comprised loose centimetric gravels and limestone pebbles dispersed on a slightly more compact layer produced by trampling and leaching of the same materials as well as a finer, sandy fraction. The surface had a regular topography, with a slope of 4 to 5 degrees. The experimental corridor was divided into a) an upstream quadrangular corridor (4 m long and 1 m wide, with its greatest length in the direction of the steepest slope), delimited by two parallel metallic rails and divided into sixteen 25-cm-wide segments labelled "A" to "P"; and b) an unrestricted zone, denoted "Q", downstream of the corridor. For each experiment, 1) a pile of knapped flint comprising variously-sized pieces and bone fragments (burnt and unburnt bone, compact and spongy tissue) were placed in bays "A" and "B"; 2) 66 litres of water were emptied from a tank into the experimental corridor eight times (approximately 528 litres in total); 3) objects were recorded per bay in the upstream zone (bays "A" to "P"), as well as in the downstream zone ("Q"). For each run of the experiment, photogrammetric models were generated, and photographs were taken every half-second using GoPro cameras placed above the experimental corridor.Statistical analyses highlight differential mobility according to:- type of material: bone remains are more mobile than flint remains. Regardless the size class, bays A and B always yielded more flint than bone remains.- bone structure: spongy bone is significantly more mobile than compact bone. - size: smaller materials between 4 and 20 mm are more mobile than remains longer than 20 mm.- combustion stage: burnt bones are more easily set in motion by water.The sorting of the material during the experiments is directly correlated with the density of the remains. For the same size class, burnt cancellous bone is the most mobile, followed by burnt compact bone, unburnt cancellous bone, unburnt compact bone and, finally, flint. Overall, our experiments revealed all categories and size classes of faunal remains to be more readily displaced by water flow compared to lithic remains, regardless their size. This differential mobility has important implications for zooarchaeological interpretations. Using the data generated during our experiments, we carried out a discriminant analysis of burnt bone assemblages per bay based on criteria traditionally used by Palaeolithic zooarchaeologists. The displacement of cancellous bone by turbulent flow produced a bone assemblage downstream that could be misinterpreted as evidence of the use of bone as fuel. At the same time, bone clusters resulting from the use of bone as fuel could be depleted in burnt cancellous elements due to water action, and therefore unrecognized in zooarchaeological analyses.Based on the results of our experiments, minor size sorting of lithic remains is accompanied by a significant sorting of all types of faunal remains, or even their almost total disappearance. Conversely, when no sorting is evident, our experiments nevertheless demonstrate that this is not necessarily indicative of well-preserved faunal assemblages. Our results show that assessing the integrity of bone assemblages on archaeological sites cannot be based on the size distribution of lithic artifacts alone. Furthermore, in cases where geoarchaeological studies have highlighted sedimentological processes involving turbulent flow, precaution must be taken in zooarchaeological interpretations, particularly regarding the representation of the axial skeleton, the presence of burnt bones, or the potential use of bone as fuel.

[fr] Les vestiges lithiques et fauniques constituent les principaux témoins des occupations paléolithiques. Les proportions relatives de ces matériaux au sein des assemblages sont utilisées pour définir la fonction des sites ou parties de site. Or, de nombreux processus naturels sont susceptibles d'occasionner des tris sur les ensembles de vestiges, parmi lesquels les écoulements turbulents, intervenant dans de nombreux domaines (e.g. fluviatile, ruissellement concentré). Afin d'évaluer cet impact, de nombreuses expérimentations ont déjà été réalisées, mais peu d'entre elles ont concerné à la fois les vestiges fauniques et lithiques. Ainsi, l'impact comparé des écoulements de régime turbulent sur ces deux types de vestiges reste difficile à caractériser. De plus, la plupart des expérimentations connues concernent des ossements complets, parfois encore articulés, rendant toute comparaison difficile avec le référentiel fossile où les ossements sont fracturés et brûlés lors des activités de subsistance.Dans cet article, nous présentons les résultats d'une expérimentation dont l'objectif était d'évaluer l'impact relatif d'un écoulement turbulent sur différentes catégories (silex, vestiges osseux brûlés et non brûlés, tissu compact et spongieux) et classes de taille de vestiges.Le principal résultat de cette expérimentation est la mise en évidence d'une mobilité plus forte de toutes les catégories et classes de taille de vestiges fauniques par rapport aux vestiges lithiques, et ce quelle que soit leur taille.Le tri généré est corrélé à la densité des vestiges, soit, du plus mobile au moins mobile : l'os spongieux brûlé, l'os compact brûlé, l'os spongieux non brûlé, l'os compact non brûlé et le silex. Par ailleurs, nous avons pu mesurer qu'un tri dimensionnel même léger des vestiges lithiques implique un tri conséquent des ensembles de vestiges fauniques. Dans le cas inverse, lorsque l'analyse granulométrique des vestiges lithiques ne révèle pas de tri, nos expérimentations soulignent que ce résultat ne peut être avancé comme argument pour un bon degré d'intégrité des ensembles fauniques.Ainsi, lorsque des processus sédimentaires impliquant des écoulements concentrés sont mis en évidence par les études géoarchéologiques, des précautions doivent être prises concernant les interprétations d'ordre archéozoologique.