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August): Response of the Rhine-Meuse fluvial system to Saalian ice-sheet dynamics.A new reconstruction of the interaction between the Saalian Drente glaciation ice margin and the Rhine-Meuse fluvial system is presented based on a sedimentary analysis of continuous core material, archived data and a section in an ice-pushed ridge. Optically Stimulated Luminescence (OSL) was applied to obtain independent age control on these sediments and to establish a first absolute chronology for palaeogeographical events prior to and during the glaciation. We identified several Rhine and Meuse river courses that were active before the Drente glaciation (MIS 11-7). The Drente glaciation ice advance into The Netherlands (OSL-dated to fall within MIS 6) led to major re-arrangement of this drainage network. The invading ice sheet overrode existing fluvial morphology and forced the Rhine-Meuse system into a proglacial position. During deglaciation, the Rhine shifted into a basin in the formerly glaciated area, while the Meuse remained south of the former ice limit, a configuration that persisted throughout most of the Eemian and Weichselian periods. An enigmatic high position of proglacial fluvial units and their subsequent dissection during deglaciation by the Meuse may partially be explained by glacio-isostatic rebound of the area, but primarily reflects a phase of high base level related to a temporary proglacial lake in the southern North Sea area, with lake levels approximating modern sea levels. Our reconstruction indicates that full 'opening' of the Dover Strait and lowering of the Southern Bight, enabling interglacial marine exchange between the English Channel and the North Sea, is to be attributed to events during the end of MIS 6.

International audienceThe Roer Valley Rift System (RVRS) is located between the West European rift and the North Sea rift system. During the Cenozoic, the RVRS was characterized by several periods of subsidence and inversion, which are linked to the evolution of the adjacent rift systems. Combination of subsidence analysis and results from the analysis of thickness distributions and fault systems allows the determination of the Cenozoic evolution and quantification of the subsidence. During the Early Paleocene, the RVRS was inverted (Laramide phase). The backstripping method shows that the RVRS was subsequently mainly affected by two periods of subsidence, during the Late Paleocene and the Oligocene–Quaternary time intervals, separated by an inversion phase during the Late Eocene. During the Oligocene and Miocene periods, the thickness of the sediments and the distribution of the active faults reveal a radical rotation of the direction of extension by about 70–80j (counter clockwise). Integration of these results at a European scale indicates that the Late Paleocene subsidence was related to the evolution of the North Sea basins, whereas the Oligocene–Quaternary subsidence is connected to the West European rift evolution. The distribution of the inverted provinces also shows that the Early Paleocene inversion (Laramide phase) has affected the whole European crust, whereas the Late Eocene inversion was restricted to the southern North Sea basins and the Channel area. Finally, comparison of these deformations in the European crust with the evolution of the Alpine chain suggests that the formation of the Alps has controlled the evolution of the European crust since the beginning of the Cenozoic

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In this study we investigate the relative importance of changes in land use and climate on suspended sediment yield (SY) on millennial timescales in the Meuse basin. We use a spatially distributed soil erosion and sediment delivery model (WATEM/SEDEM) to simulate SY in three time-periods: 4000-3000 BP (minimal anthropogenic influence); 1000-2000 AD (includes land use and climate change); and the 21st Century. Changes in climate are based on climate model output (ECBilt-CLIO-VECODE). For the 21st Century the model is forced according to two emission scenarios of the Intergovernmental Panel on Climate Change (IPCC), namely the SRES scenarios A2 and B1. These scenarios lie towards the higher and lower end of the full IPCC scenario range respectively. For 4000-3000 BP the basin is assumed to be almost fully forested; for 1000-2000 AD land use is reconstructed using CORINE data, historical sources, and land use modelling; and for the 21st Century land use is based on the European land use change project EURURALIS. Whilst rainfall erosivity increases by only 3% between 4000-3000 BP and 1000-2000 AD, SY increases from ca. 92 000 Mg a − 1 to ca. 306 000 Mg a − 1 . This model prediction is in agreement with the limited regional multi-proxy data available. Our simulations show that almost all of this increase is due to the conversion of forest to agricultural land. Over the period 1000-1900 AD, SY shows a significant increasing trend, with a peak of ca. 388 000 Mg a − 1 in the 19th Century (due to continuing deforestation). In the 20th Century, reforestation and rapid urbanisation result in a decrease to ca. 281000 Mg a − 1 . Sensitivity analyses show that although land use change acts as the primary control on long-term changes in SY, the sensitivity of SY to changes in climate increases as the percentage of deforested land increases. For the 21st Century the results are highly sensitive to the scenarios used. Due to relatively large increases in rainfall erosivity, SY increases by 12% compared to the 20th Century according to scenario A2, or by 8% according to B1. However, the associated land use change scenarios cause decreases in SY by 26% (A2) and 46% (B1). The net effect is thus a decrease of SY. This study highlights the potentially significant efficacy of land use planning as a tool to mitigate the negative effects of soil erosion and sediment delivery to rivers.

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