International audienceNorthwestern France is at the western end of the Eurasian loess zone characterized by a subcontinuous loess cover. It contains a large amount of Lower and Middle Paleolithic open-air sites. This region, and in particular the valley of the Somme, has played a essential role in the of history of Prehistory. It constitutes, still at the present time, a zone of,leading search and a reference region for prehistorians.The Middle Palaeolithic.of Northwestern France is characterized by the presence of many Middle Palaeolithic sites, covering the entire period. The Saalian phase is less documented, partly for taphonomic reasons. The lithic industries indicate mastery of all production systems for flakes, blades, points and to a...