Researches during the last 20 years on both fluvial and loess sequences of the main river valleys in Northern France (Somme, Seine and Yonne) are based on an interdisciplinary approach combining stratigraphy, sedimentology, bioclimatic studies and advanced dating methods (U/Th, ESR, OSL).
From a general point of view, it seems likely that Human occupation of the Somme, Seine and Yonne basins has been discontinuous and highly influenced by climatic and environmental factors . In the Somme basin the oldest demonstrated human occupations are dated at a maximum 500 k.a. (Early OIS 12, Cagny-la-Garenne) and are already represented by an evolved Acheulean . In the Seine basin, the oldest Acheulean archaeological level has been evidenced at La Celle, within a tufa sequence attributed to MIS 11 and dated at 400-420 k.a by U/Th and ESR. Between 450 ad 200 ka the data are relatively rare and less accurate but the archaeological sites were nevertheless mainly located during interglacial periods (La Celle, Saint-Acheul, Soucy, Cagny-Epinette) or during climatic transition (Early or Late glacial cycles).
Taking in account the whole data and especially the available dating results for the oldest levels, the Acheulean don’t seem to have occurred in the area before 500 ka. Indeed, the old discoveries as those the “Marne blanche” at Abbeville (MIS 15, ± 600 according to its relative height in the system and to ESR results), need to be confirmed by new investigations.
Since 1994, archaeological supervision of a gravel quarry located on the middle terrace of the River Yonne at Soucy (Yonne), in the north of Burgundy some 120 km south east of Paris, has permitted the discovery of several prehistoric sites included in middle Pleistocene sequences. Since the quarry was opened in 1990, nine archaeological horizons have been identified across 6 sites, four of which have been excavated (Soucy 1, 3, 5 and 6) and two of which have been preserved in situ for excavation at a future date. Stratigraphic, biological and radiometric dating places these sites between c.345 and 365 k.a. (MIS10/9). The Soucy localities tell a story of successive hominin occupations in a fluvial landscape. Many of the occupations show distinctive patterns of behavior by the presence or absence of typical Acheulian bifaces.
On the other hand even older human occupations seems to appear more to the south in the Cher Valley (Lunery, La Noira) as on the other side of the Channel (High Lodge, Pakefield, Happisburgh 1-3, Cromer). Taking in account these observations, it is likely that the main river valleys from the south side of the Channel (Somme, Seine), representing main migration routes during periods of low sea levels, may also contain very old Acheulean occupations contemporaneous of the older phase of the Cromerian complex (± 500-650 k.a.) that are still to be evidenced.