Weichselian to Early Holocene vegetation development and fluvial adjustment in the Lower Rhine Valley, Germany - The role of climate change, glacio-isostasy and intrinsic characteristics of the river system

Abstract

In the downstream part of the lower Rhine valley, Germany, at least four floodplain levels of pre-Holocene age can be distinguished, based on plan view channel patterns, top elevation of sandy channel deposits and lithological characteristics. For this reach of the Rhine valley, a new floodplain level chronostratigraphy was constructed on the basis of geomorphological relationships and a correlation to the well-dated sedimentary record of the Rhine-Meuse delta. Factors which are concluded to have predominantly influenced river functioning during the Weichselian are climate and climate derived characteristics of the river catchment, glacio-isostatic uplift and subsidence and time-lags between sediment-input- and discharge-related alterations of the upper catchment and the moment of registration downstream. Typical for the downstream part of the lower Rhine valley, is that channel systems making part of abandoned river terraces kept an important role in draining water during periodical floods. This caused partial infilling of the channels with clastic material and initially inhibited infilling with organic (autochtonous) material. This type of fluvial activity produced considerable time-lags (up to several millennia) between initial channel abandonment and the onset of organic channel infilling, making pollen records of Lateglacial age very rare in this area.