Rare are new testimonies for the MIS 11 to 9 in Eurasia. The discovery and the excavation of a new site in 2012 at Etricourt-Manancourt (Somme, France) in a very large area was an exceptionnal event. In 2010, at the place of the future retention basin, a palaeolithic trial excavation was carried out by Emilie Goval on 170 000 square meters. It produced many flint artefacts, proving the existence of at least two important Middle Palaeolithic sites. In 2012, an excavation on the first favourable sector was conducted by David Hérisson over 6 months on 4500 square meters. This excavation has been leaded by a multidisciplinary sicentific team, including prehistorians, geomorphologists. This allows us to apply an reliable chronostratigraphical approach based on the sequential analysis of glacial-interglacial deposit successions. Five palaeolithic occupations have been excavated in situ, dating from 330 to 80 ky. The youngest occupation dates from 70-80 ky and corresponds to a recent phase of the Middle Palaeolithic. The next two layers belong to the Early Middle Palaeolithic during the Saalian, between 190 and 240 ky. Finally, the two oldest layers have dates between 330 and 280 ky and belong to the Lower Palaeolithic. In addition to this archaeological wealth, the sedimentary sequence is very dilated (11 meters high) and presents for the first time in Northern France a continuous record of the three last interglacial-glacial cycles. This talk will present archaeological and chronostratigraphical results of the excavation of Etricourt-Manancourt and its input with high resolution datas to discuss behavioural changes occurring at the end of the Lower Palaeolithic and the onset of the Middle Palaeolithic.