Original paper

Floodplain sediments of some streams in the Taunus and Westerwald Mts., western Germany, as evidence of historical land use

Stolz, Christian; Grunert, Jörg


Flood loams of the valley floors of central European rivers have been studied since the 1950s. For the Weser River, MENSCHING (1952) showed a direct link between flood-loam deposition and soil erosion of loesses in its catchment. HEMPEL (1959) found archaeological evidence of flood-plain sedimentation during the High Middle Ages, which at that time was regarded as a local phenomenon. Based on these studies three catchments in the eastern Rhenish Slate Mountains have been studied: the Aar Valley of the northern Taunus foreland, the Wisper Valley of the western Taunus Mountains, and the Nister Valley of the High Westerwald Mountains. In the main study area, the Aar Valley, two floodplain meadow sites have been studied, the Weiherwiesen at Adolfseck/Bad Schwalbach, and the Schmidtwiesen, 10 km downriver of Adolfseck. The swampy Weiherwiesen are a former meander loop, cut off in AD 1355 and transformed into a mill pond, a few ha large, that existed until 1820. During those 465 years clayey to silty sediments were deposited in it, easily distinguished from the underlying, somewhat coarser original flood loam. In comparison with an undisturbed floodplain section a few 100 m downriver (Fahrwiesen), it could be determined that 47% of the flood loam are older, and 53% younger than AD 1355. The young age of most of the flood loam has been confirmed by an iron-slag site buried beneath 80 cm of flood loam at the Schmidtwiesen locality, radio-carbon-dated to AD 1427 to 1471. The layer of flood loam deposited before that date is considerably thinner. The flood loam of the Wisper Valley is much thinner than that of the Aar Valley floor, most likely due to much less deforestation in the catchment in High Medieval times. The steep slopes of the catchment are mainly blanketed by the basal layer of the cover bed of Pleistocene periglacial quartzite debris; the loess cover representing the main layer is only thin. Conditions were thus unfavourable for agriculture, resulting in only little soil erosion. For lack of archaeological remains or datable material the flood loam of the valley floor could not be differentiated. The same is true for the Nister Valley. The flood-loam cover there is similarly thin and uniform, which is surprising, as numerous charcoal kiln sites within the catchment are evidence of Late Medieval and Post-Medieval forest clearing. The climate is so humid, though, at more than 1,000 mm/y, that there never was much agriculture, and thus again hardly any soil erosion. Despite the lack of hard evidence, it is likely, by analogy to the Aar valley, that the upper parts of the floodloams of the Nister and Wisper valleys are equally of Post-Medieval age.