| dc.description.abstract | This thesis focuses on the response of the Maas river to Lateglacial and Early Holocene climate and vegetation changes between Susteren and Venlo, Southern Netherlands. Upstream of the research area, the terrace stratigraphy has been investigated earlier; four different terraces have been distinguished. According to the previous studies, the oldest terraces, the Rijkevoort and Milsbeek terraces were formed during the Late Pleniglacial, by the Maas river that had a braided pattern in this period. Next, the Vierlingsbeek and Gennep terraces were formed during the Bølling; the Maas started to meander and to incise. During the Older Dryas the incision stopped although no change in channel pattern or terrace has been observed. The Broekhuizen terrace was formed during the Allerød with high-sinuous meanders which incised a few meters. During the Younger Dryas the Wanssum terrace was formed by an again braided river Maas. Finally, during the Holocene, a narrow and straight edged floodplain was used with low sinuosity meanders.
In this report, a comparison has been made between the terrace stratigraphy from Born to Venlo and upstream of Venlo. For this purpose, the infills of four different palaeochannels of the Maas between Born and Venlo have been studied. First, lithological cross-sections have been constructed, while at the deepest part of the channel a core was taken for further analysis. In the laboratory loss on ignition and calcium carbonate content measurements were performed. Also pollen samples were taken from most organic layers in the core to reconstruct an age model for each core. These age models were based on correlating the most important transitions in the pollen assemblages in the cores that correspond to the well-known vegetation development in the Netherlands during the Lateglacial to Early Holocene. Some of the selected residual channels did not meet the expectations for organic infill and/or were anthropogenically disturbed; on these locations the age was determined based on a pollen quick scan.
Three out of four of the investigated palaeochannels (Dukkelaar, Houterhof and Katerhof) were located on the Pleniglacial floodplain; initially an infill of Lateglacial age was expected. The other palaeochannel (Casquettenhof) was located on the Holocene floodplain; the time of infill of this channel was expected to be Early Holocene. Pollen diagrams of all these channels show a different outcome than expected. The infilling of palaeochannel Dukkelaar started during the Younger Dryas. The start of infill in Houterhof was Late Boreal-Atlantic. The infill of palaeochannel Katerhof started during the Atlantic-Subboreal. At the palaeochannel Casquettenhof two cores were taken due to the differences in organic infill, the ‘oldest’ core started during the Iron Age in the Subatlantic, the ‘youngest’ core started in the Ancient Roman time in the Subatlantic. The differences in lithology and timing can be explained by the geographical location with respect to the present day Maas and the tectonic faults that are present. The palaeochannels Katerhof and Houterhof are probably re-used by the Maas or the Haelensche Beek, which removed/eroded older deposits. Casquettenhof is located nearby the locations of Pannenhof and Schietclub, where pollen quick scans show an Iron Age infill. These were probably connected and shifted during Medieval times more to the East (this is supported by the results of Casquettenhof 1). The meanders at Dukkelaar, Kingbeekdal and Korbusch were abandoned during the Younger Dryas, so the Maas shifted during the Younger Dryas towards the East.
Residual channel fills of the Maas between Susteren and Venlo are very different from palaeochannels downstream. Overall the channel pattern and the time of infill of the channel do not correlate with palaeochannels downstream, while the lithology and the vegetation development seems to correlate with the time of infill. These results are not consistent with the literature and previous investigations upstream of Venlo. Spatial differences in channel pattern are likely to be caused by differences in the local conditions like: tectonic faults, transition zone between the so-called ”Gravel Maas” and the “Sand Maas” and differences in elevation. Further research between Susteren and Venlo should resolve these issues. | |
