A new Middle Pleistocene loess-palaeosol sequence was uncovered during a preventive excavation at Étricourt-Manancourt (Somme, France). The full 12-m-thick sequence exhibits five stacked glacial-interglacial cycles and integrates five in situ Palaeolithic levels and remarkably one Acheulean level dated by TL on burned flints at about 280 - 300 ka. Detailed field stratigraphic approach has been completed by a high-resolution sedimentological study (grain size, TOC) based on a set of more than 380 5-cm-thick samples collected from continuous sampling columns covering the entire units, more than 110 micromorphological block samples for thin sections analysis and a set of 37 sub-samples for the study of heavy minerals. Despite specific samples (tubes) having been extracted for future OSL dating, the geochronological control is mainly based on TL dating of heated (archaeological) flints, completed by IRSL dating on K-feldspars. The study of four reference profiles distributed throughout the excavation, and their correlation using well defined pedological level marks led to the definition of a ca. 12-m-thick cumulative loess-palaeosols succession including eighteen main stratigraphic units. This approach allowed building a global pedosedimentary sequences for the Étricourt site that presently serves as a reference for northern France, and more broadly the loess belt. The archaeological excavation, located on the slope of a dry valley, was opened over more than 4500 m². Five in situ Palaeolithic occupations have been excavated, dating from 330 to 70 ka. The youngest occupation dates from 70 to 80 ka (Weichselian) and corresponds to a recent phase of the Middle Palaeolithic. The next two layers belong to the Early Middle Palaeolithic, between 190 and 240 ka (Saalian). Finally, the two oldest layers have dates between 330 and 280 ka (Saalian) and belong to the Lower Palaeolithic. We propose to present the archaeological and chronostratigraphic results of the excavation of Etricourt-Manancourt and its input with high resolution data to the knowledge of the Saalian and the Weichselian in Northern France and in North-Western Europe.