a b s t r a c t a r t i c l e i n f oThe northern Upper Rhine Graben hosts a well-preserved Late Weichselian and Holocene fluvial terrace sequence. Terraces differ in elevation, morphology, and overbank sediment characteristics. The purpose of this study was to determine the relative importance of allogenic controlling factors versus autogenic evolution on the successive formation of these terraces. For a representative valley segment (the Gernsheim region), results from previous research were integrated with newly obtained borehole data and digitized elevation maps to construct palaeogeographic maps and cross sections. Coarse-grained channel deposits below terrace surfaces were dated using Optically Stimulated Luminescence, and fine-grained abandoned channel fill deposits were dated using pollen stratigraphy and radiocarbon analysis. Initiation of terrace formation was caused by climatic change in the Late Pleniglacial (after~20 ka), but fluvial response was complex and slow and continued locally until the middle Boreal (~9 ka). Early to Middle Holocene (~6 ka) changes in fluvial style and associated overbank lithofacies are not necessarily controlled by climatic change as was previously proposed. Instead, autogenic processes combined with river reach-specific factors explain the observed terrace development. Continuous incision, autogenic evolution, and high preservation potential provide an alternative explanation for the presence of a terrace sequence in this subsiding area.

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The vegetation of the northern Upper Rhine Graben (southwestern Germany) is reconstructed for the end of the Lateglacial and the Holocene by means of palynological analyses in combination with AMS 14c dating. Analogous to adjacent lowland areas, the Younger Dryas climatic deterioration did not result in a complete deforestation of the area and open pine woodlands with locally birch stands and shrubs persisted. A subdivision of the Younger Dryas period, into a humid first phase, followed by a dry second phase was also reflected in our records. For the Holocene, the pollen diagrams show two regionally different vegetation developments, related to substrate and variations in annual precipitation: in the south the ‘classical’ succession of pine then hazel is followed by other deciduous trees, whereas in the northern part, pine kept its dominance far into the Subboreal.

Boreholes made to investigate the Neolithic occupation of the Rio Sizandro, western Portugal, were analysed for ostracods and associated micro-biota. Two boreholes in the middle reaches of the valley, near the village of Benfica, provide evidence of brackish estuarine conditions during the interval 6,500-6,200 cal BP of the late Neolithic followed by a decline in palaeosalinity towards freshwater conditions. Following the high-stand of eustatic sea level at about 6,500 cal BP, and possible formation of a coastal sand barrier, the influence of the rivers in the hinterland became predominant with dramatically increased erosion and sediment supply to the river valley, with consequent westward movement of marine conditions to the modern coastline.

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