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This paper demonstrates that the Belgian Continental Shelf and coastal plain occupy a key position between the depositional North Sea Basin and the erosional area of the Dover Strait as it is an area where erosional landforms and fragmented sedimentary sequences provide new evidence on northwest European landscape evolution. The study area hosts 20–30 m thick penultimate to last glacial sand-dominated sequences that are preserved within the buried palaeo-Scheldt Valley. Here, we build on the results of previous seismo- and lithostratigraphical studies, and present new evidence from biostratigraphical analysis, OSL dating and depth-converted structure maps, together revealing a complex history of deposition and landscape evolution controlled by climate change, sea-level fluctuations and glacio-isostasy. This study presents strong new supportive evidence on the development of the incised palaeo-Scheldt Valley landform that became established towards the end of the penultimate glacial period (MIS 6; Saalian) as a result of glacio-isostatic forebulge updoming, proglacial lake drainage and subsequent collapse of a forebulge between East Anglia and Belgium following ice-sheet growth, disintegration and retreat in areas to the north. The majority of the incised-valley fill is of estuarine to shallow marine depositional context deposited during the transgression and high-stand of the last interglacial (MIS 5e: Eemian). A thin upper part of the valley fill consists of last glacial (MIS 5d-2: Weichselian) fluvial sediments that show a gradual decrease and retreat of fluvial activity to inland, upstream reaches of the valley system until finally the valley ceases to exist as the combined result of climate-driven aeolian activity and possibly also glacio-isostatic adjustment. Thus, strong contrasts exist between the palaeo-Scheldt Valley and estuary systems of the penultimate glacial maximum to Last Interglacial (Saalian, Eemian), the beginning of the Last Glacial (Weichselian Early Glacial and Early-Middle Pleniglacial), and the Last Glacial Maximum to Holocene.

The optically stimulated luminescence (OSL) signal from fluvial sediment often contains a remnant from the previous deposition cycle, leading to a partially bleached equivalent-dose distribution. Although identification of the burial dose is of primary concern, the degree of bleaching could potentially provide insights into sediment transport processes. However, comparison of bleaching between samples is complicated by sample-to-sample variation in aliquot size and luminescence sensitivity. Here we begin development of an age model to account for these effects. With measurement data from multi-grain aliquots, we use Bayesian computational statistics to estimate the burial dose and bleaching parameters of the single-grain dose distribution. We apply the model to 46 samples taken from fluvial sediment of Rhine branches in the Netherlands, and compare the results with environmental predictor variables (depositional environment, texture, sample depth, depth relative to mean water level, dose rate). Although obvious correlations with predictor variables are absent, there is some suggestion that the best-bleached samples are found close to the modern mean water level, and that the extent of bleaching has changed over the recent past. We hypothesise that sediment deposited near the transition of channel to overbank deposits receives the most sunlight exposure, due to local reworking after deposition. However, nearly all samples are inferred to have at least some well-bleached grains, suggesting that bleaching also occurs during fluvial transport.

We investigate the use of quartz optically stimulated luminescence (OSL) dating for determining fluvial overbank sedimentation rates over decades to centuries. For the study we took 11 samples from three cores from an embanked floodplain along the River Waal (Rhine) near Neerijnen (The Netherlands). We propose a measurement protocol for young fluvial quartz based on the single-aliquot regenerative dose procedure. Parameters for the protocol are chosen to isolate the fast OSL component, eliminate an ultrafast OSL component and avoid thermal transfer. The protocol shows excellent dose recovery and recycling ratios. For each sample, a Gaussian is fitted to the lower part of the equivalent dose distribution to obtain an estimate of the burial dose. We discuss the validity of the OSL ages using internal and external controls, and conclude that there is no evidence for large systematic offsets in the OSL ages. OSL based sedimentation rates are between ∼3 and 8 mm/a, in line with previous estimates.