| Summary: | International audience In Northern France Quaternary loess-palaeosol sequences represent the main deposits in which Palaeolithic sites are generally recovered. The oldest loess, dating from the Middle Pleistocene, are generally preserved in sedimentary traps formed by the junction between the chalky slopes and the alluvial formations of the Somme River fluvial terrace system or by deep sinkholes (3-5 m) resulting from the dissolution of the chalky substratum on the plateaus. They are mainly resulting from local deflation processes reworking the top of sandy fluvial deposits. A large extension of typical calcareous loess over the whole landscape is only observed from the end of the Saalian (ca. 150-135 ka). The heavy mineral content of these aeolian deposits testifies to a distant transport from the polar desert areas of the dried Eastern Channel (≥ 100 km). Following the last Interglacial (Eemian), the Last glacial (Weichselian) is represented by a sub-continuous loess cover rising up to 7-8 m in thickness in the best locations as leeward slopes. In this large area, pedostratigraphic sequences from the last Interglacial-glacial cycle have been intensely studied, especially in the frame of rescue archaeological programs that have provided hundreds of individual sequences from test-pits or excavations and numerous archaeological layers. The pedostratigraphic sequences from the last Interglacial-glacial cycle exhibit a regular pedosedimentary pattern including well identified pedological and periglacial marker horizons that can be followed towards the East at least in Belgium and Germany. This approach leads to a detailed pedostratigraphic and chronostratigraphic scheme that represents a unique database to discuss the relations between Palaeolithic occupations and environment in Europe. It can be summarised by the succession of four main chrono-climatic phases following the erosion of the eemian brown leached soil during MIS 5d: (1) Early-glacial (112-72 ka) including a phase with grey forest soils (Early-glacial ...
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