Ecology and fluvial dynamics of an Early Holocene medium-sized European lowland river valley (Upper Scheldt, northern Belgium)

The fluvial environment of Early Holocene small- to middle-sized lowland rivers in northwest Europe is mostly unstudied due to a lack of preserved and accessible deposits. A rescue excavation in the Scheldt valley in northern Belgium offered the opportunity to study a Boreal alluvial succession in detail. The results of palaeoecological and sedimentological analyses (diatoms, pollen, botanical macro-remains, molluscs, grain size) characterize the biotic and physical environment in the middle reach of this medium-sized river system. Although the Early Holocene in the Scheldt Basin has often been portrayed as a period of fluvial stability with marshy conditions and diffuse discharge, this study showed evidence of point bar formation by a small, low-energy meandering river between similar to 9.5 and similar to 8.8cal. ka BP. The point bar was at least temporarily vegetated and shows a shift from herbaceous riparian vegetation to an open willow-dominated alluvial forest. This evidence points to a more open vegetation and a more energetic environment than traditionally described for rivers of this size and age. A link to the 9.3 ka BP cooling event is suggested and possible reasons for the scarcity of records of this type of deposits are discussed