11 From the Middle to the Upper Pleistocene Origins and diversification of the Middle Palaeolithic in Northwest France Jean-Luc Locht, David Hérisson and Emile Goval Introduction The first settlement of Northern Europe occurred at the end of the Lower Pleistocene (Happisburgh, Ashton et al. 2014), then in a more palpable way during the long interglacial phases of the second half of the Middle Pleis- tocene. At that time, Europe was a geographic cul-de-sac. The isolation of European Homo erectus populations during this period led to the emer- gence of a typically European species, Neanderthal, and to the advent of Mousterian cultures (Hublin and Roebroeks 2009; Otte 2015. During this period, the North of France played a fundamental role in the colonisation of the northern territories and the settlement of England (Chapters 7–10). The sedimentary and archaeological record The North of France, and the whole of Northern Europe underwent marked climatic variations during the Quaternary, linked to the succession of Glacial-Interglacial cycles. These variations had strong impacts on sedimen- tary dynamics. Phases marked by erosion were frequent. Two main morpho- sedimentary contexts can be distinguished: fluviatile formations and loess deposits. For the Middle Pleistocene, most of the information on fluviatile records comes from the alluvial water table from the Middle Valley of the Somme, between Amiens and Abbeville (Figure 11.1) (Antoine 1990). Ten stepped terraces were identified for the period spanning the past million years. They are mainly located in a confluence position between the Somme and the adjacent rivers (Figure 11.2) (Antoine et al. 2014). These terraces are made up of gravel deposits (Pleniglacial phases), overlain by fine fluviatile sediments (silts, sands or tuffs, mainly during Tardiglacial and interglacial phases), which are very exposed to processes of erosion. These fine, some- times carbonated sediments, can preserve Lower Palaeolithic (e.g. Amiens 15032-0720d-1pass-r03.indd 215 04-10-2017 11:48:01 Article 9