The Bode, which has its source in the Harz Mountains,
changes its course almost at right angles over the Oschersleben Salt Saddle and assumes the Hercynian direction of the subrosion depressions. According to historical maps, the river had formed bifurcations within the Espenbruch. The meanwhile inactive river courses can be visualized in the digital terrain model (DTM).With the help of airborne
... [Show full abstract] laser scans (ALS), a flat morphological elevation can be detected directly above the Oschersleben Salt Saddle. It crosses the Holocene foodplain of the Espenbruch in the correct position above the saddle and is also visible west of the river Bode in the alluvial plane Großes Bruch. This linear morphological structure is due to a neotectonic uplift in the crest of the Oschersleben Salt Saddle. Apparently at the end of the Middle Ages, the elevation of the terrain impeded the water fow of the rivers Bode and Großer Graben. As a result of the backwater, the Bode upstream has given way to an existing bifurcation.The existence of periodic tributaries of the Bode in the area of the Espenbruch can be proven on the basis of borhole
profiles. In the floodplain to the east of the main course,
coarse clastic sediments can be found along the old river
routes under the fine-grained cover layers of the floodplain.
The river gravels of Bode, characterized by Palaeozoic resin rocks (e. g., Rammberg granite, diabase, lyddite) can be clearly distinguished from Pleistocene gravels. Their occurrence outside of the recent main course can be evaluated as geological evidence for the historical changes in the
course.
