Palaeomorphology in the eastern Scheldt basin (Central Belgium) - The dijle-demer-grote nete confluence area -

J. Vandenberghe*, P. de Smedt

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

The study of a part of the eastern Scheldt basin (Central Belgium) showed that a multidisciplinary approach is a very appropriate means to reconstruct a regions palaeomorphology. The evolution of the confluence area of three river systems (Dijle, Demer, Grote Nete) flowing in three different directions (S-N, E-W and NE-SW) was studied. The fossil river incisions were reconstructed by means of a geoelectric survey. The electric specific resistivities of the Quaternary fluvial sediments differ clearly from the specific resistivities of the Tertiary subsoil. Consequently, the base of the fluviatile deposits could be found very accurately throughout the confluence area. Palynological and sedimentological analyses assisted the relative dating and the environmental reconstruction. The intense lowering of the relief during the Middle Pleistocene was accompanied by the replacement of the consequent river system in the eastern Scheldt basin by a system more adapted to the geological structure. A fossil course of the Grote Nete had been discovered earlier. Moreover, some buried terrace levels could be found and the deepest points of the gully incisions were localized. Some levels were interpreted as cryopediments, other levels developed as river terraces. These results also allowed the levels along the three rivers to be correlated. An asymmetric development of these levels could be attributed to the different lithological composition of the subsoil. The deep incisions were filled up during the last glacial. During the Late Weichselian the meandering rivers incised again a few metres. Abundant aggradation was the cause of deviations of the Demer and Dijle rivers at the end of the Younger Dryas and at the end of the Subboreal. The Holocene river floodplain was built up by peat (Preboreal-Boreal), clayey loams (Atlantic-early Subboreal) and sandy loams (since end Subboreal). The Boreal and Subboreal were periods of renewed shallow erosion.

Original languageEnglish
Pages (from-to)73-105
Number of pages33
JournalCatena
Volume6
Issue number1
DOIs
Publication statusPublished - 1 Jan 1979

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