Quaternary Landscape Response to Climate Change The last millennia history of detrital sedimentation in the Lower Seine Valley (Normandy, NW France): review S. Sechi, 1 D. Sebag, 1 B. Laignel, 1 T. Lepert, 2 M. Frouin 3 and A. Durand 1 1 Universite´ de Rouen, CNRS, Laboratoire M2C, UMR 6143, Mont-Saint-Aignan, France; 2 Universite ´ Paris I & X, CNRS, MCC (Ministe`re de la Culture et de la Communication), Laboratoire ArScan, UMR 7041, Nanterre, France; 3 INRAP Grand Est Nord, 38 Rue des Dats, 51520 St Martin sur le Pre ´, France Introduction The respective roles of climate and Man in Holocene environmental changes are still debated. Indeed, these factors are together implicated in changes in hydrological balance, soil erosion and terrigenous sedimen- tation that have occurred since Neo- lithic times. Thus, in Northwest Europe, increasing land use is well documented as forest clearance, alter- nation of deforestation and farming periods, and forest recovery episodes (Oldfield, 1963, 2008; Dumayne-Peaty and Barber, 1998; Roesch, 2000; Wim- ble et al., 2000; Oldfield et al., 2003). In this respect, the lower valleys were particularly sensitive to changes and provide valuable Holocene archives to track variability in sedimentary dynamics (Macklin, 1999). Several studies have emphasised the Quaternary and Holocene of the Low- er Seine Valley (LSV), West Paris Basin (Normandy, France), as a con- sequence of climate changes or sea-level rise or human activities (e.g. Lefebvre et al., 1994; Antoine et al., 2000, 2007; Frouin et al., 2006, 2007a, 2010). The combined impact of climatic extrema and changes in land use induces soil erosion processes, which result in terrigenous sedimenta- tion episodes (Sebag, 2002; Laignel, 2003). However, no study has yet been initiated that describes and analyses the pattern of soil erosion and terri- genous sedimentation records at the regional scale. The main objective of this paper is to trace the history of the erosional processes in the LSV using sediments as erosional records. Recognised events are placed in a chronological and archaeological context and com- pared with the neighbouring regions. Previous studies The LSV is the major drain axis of the Western Paris Basin (Fig. 1A) and is a macrotidal estuary flowing into the English Channel. The study area of the LSV comprises a chalky substra- tum covered by surficial formations. Several geomorphical compartments were identified according to their nature, lithology and ⁄ or genesis (Fig. 1B): (1) chalky plateaus and their weathering cover (clay-with- flints), sandy–clayey residual deposits (plateau loessic limons; Laignel et al., 1999, 2002a); (2) slope-clay-with-flints resulting from solifluxion processes from plateau alterites (Laignel et al., 2002b) and (3) the Seine River and its tributaries stocking various alluvial plain sediments (loamy and peaty deposits; Sebag, 2002; Laignel, 2003). Since the 1960s, different sites in the LSV have been investigated (Fig. 1). They include the Seine bay (Garnaud et al., 2003), the Seine estuary (Dels- inne, 2005; Sorrel et al., 2009), the Marais Vernier (Elhaı¨, 1959; Huault, 1980, 1985; Huault and Lefebvre, 1983; Frouin et al., 2006, 2007a,b, 2009), the Heurteauville peatland (Huault, 1986) and the Berville sur Seine meander (Sebag, 2002; Sebag et al., 2006a,b). Tributaries of the Seine River (TSR) were the object of unpublished studies on archaeological surveys carried out by Service Re´gion- al de lÕArche´ologie (SRA): Brionne, Pont Audemer, Incarville and Louviers. Three main compartments of the LSV can be recognised: the estuarial zone (abandoned meander of Marais Vernier) with mainly marine palaeobiological and mineralogical markers; the fluvial zone (Berville sur Seine backswamp) with terrestrial organic and mineralogical markers; and the TSR catchment area (Brionne, Pont Audemer, Incarville and Louviers) with detrital terrigenous sedimentation. Estuarine zone The sandy and clayey unit, at the bottom of the Marais Vernier marsh sequence (Fig. 2), is the first Holocene ABSTRACT Post-glacial climate changes and sea-level fluctuations have strongly influenced N-W European environments and sedimen- tation. To these natural events, increasing anthropogenic pressure has to be added. Forest clearance and agricultural development are the main factors responsible for the erosional processes in Northwest Europe. This article analyses Holocene sequences of the Lower Seine Valley (LSV) (Paris Basin) to understand better the origin of detrital and terrigenous input and how much humans have contributed to it. Three main sectors of the LSV are analysed: estuarine, fluvial and tributar- ies. Since Neolithic times, there are seven erosional phases that can be identified and essentially linked to human pressure. Terra Nova, 22, 434–441, 2010 Correspondence: Dr Serafina Sechi, De´ part- ement de Ge´ologie et Laboratoire M2C, Universite´ de Rouen, Baˆt. IRESE A Place Emile Blondel, Mont-Saint-Aignan Cedex 76821, France. Tel.: 00 33 2 35 14 69 52; e-mail: serafina.sechi@gmail.com This paper forms part of a thematic set of articles guest-edited by Professor Vincenzo Pascucci on the topic of Quaternary land- scape response to climate change and pre- sented at the 2009 IAS Alghero conference. 434 Ó 2010 Blackwell Publishing Ltd doi: 10.1111/j.1365-3121.2010.00972.x