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Two cores were drilled in the river Drômes's vast and thick (10-12 m) holocène alluvial cone, where it flows into the river Rhône. The presence of alterning layers of terrigenous silty-clayey sediments and organic peaty loam made it possible - thanks to sedimentology and radiocarbon dating - to identify the different evolving phases of the river. The period of post-maxi wurmian river-bed formation ends before 11 850 B.P. It is followed until 7000 B.P. by a period of low accumulation (average rate: 10 centimeters per 1000 years) and then between 7000 B.P. and 3000 B.P., by a stage of accelerated accumulation (2 meters per 1000 years). Subsequently and up to the present the average rate drops markedly (50 centimeters per 1000 years), although this doesn't necessarily indicate a decrease in erosion phenomena nor a slowdown in downstream accumulation : increase in the cone's surface area and retention of recent upstream accumulation. We would suggest an attempted correlation between on the one hand the detrital accumulation crisis from 7000 B.P., and on the other, the early and large anthropisation of the mountain basin during the Middle and perhaps even Early Neolithic periods equally demonstrated by pollen analysis. Therefore could be explained the importance of both upstream erosion phenomena and downstream accumulation.

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Discovered in 1986, La Grande Rivoire is a rockshelter located in the north of the prealpine mountain range of Vercors (Northern French Alps). It lies at 580 m asl, on the west side of the Furon valley, at the foot of a cliff. The 6-m stratigraphy reveals a continuous chronocultural sequence starting from the First Mesolithic to the Gallo-Roman period. The present communication aims at characterizing the earliest occupation of the site attributed to the First Mesolithic (ca. 8500–7000 cal. BC). The new multidisciplinary data are intended to contribute to the understanding of the regional chronocultural evolution. The deposits are constituted of very rich organic materials, possibly resulting from the degradation and combustion of plant litters. Their natural and/or anthropogenic origin still remains unclear. The excellent state of preservation of the faunal remains (superficially covered of an ashy encrustation) and the bone refittings would indicate a low post-depositional impact on the faunal material in this sector. The highly intentionally fragmented long bone remains indicate (intensive?) carcass exploitation of various large game species, among which red deer seems to predominate. Plant remains analysis gives also information on wild picking products, especially hazelnuts. Osseous material industry is dominated by waste products occurring from sectioning action of red deer antler by notching. Few examples of bone and tooth working highlight the use of removal by diffuse percussion during shaping. Preliminary observations conducted on the lithic assemblages show that domestic tools are mostly manufactured on local raw materials of poor quality. Exogenous raw materials of better quality are mainly used for the fabrication of microliths using the microburin technique; the latter tending to disappear at the end of the sequence. Usewear analysis on arrowheads shows that triangles are present throughout the sequence and always hafted as barbs while Sauveterre points and segments are only present in the oldest decapages

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