How the Late Pleniglacial Landscape Changes Diversified the Gravettian Record of Ach & Lone Valleys
Channel: Recording Archaeology
Date: 2017-10-11

The Ach and Lone valleys of the Swabian Jura (In Bade-Württemberg, Southwest Germany) represent a key region in the study of human migrations in central Europe. In contrast with the Aurignacian and the Magdalenian, the Gravettian record preserved in the cave sites of these two valleys is poorer and appears variable. Previous lithic analyses conducted on the Gravettian stone tools of the Ach Valley have discovered multiple refitted artefacts found across several different cave sites, which might indicate that this part of the Jura was repeatedly occupied by the same group of humans. In contrast, in the Lone Valley material and 14C dating indicative of the Gravettian occupation are sparser and are largely redeposited within younger sediments. Over the past years we have investigated the natural processes that shape the landscape and the cave deposits of these two valleys. By combining a variety of methods (including geophysical prospection, coring, micromorphology, FTIR, and radiocarbon dating) we demonstrate that alternating phases of soil formation, hillside denudation, river valley incision and floodplain aggradation have been the major processes active in the Lone and Ach valleys throughout the Pleistocene and Holocene. Here we evaluate how local variables (such as valley gradient, drainage basin extent, size and relative elevation of caves) influenced these processes and their impact on cave sedimentation. Our results suggest that a phase of river valley incision and subsequent, intensive mass wasting of the hillsides promoted the erosion of Gravettian-aged deposits from the caves of these valleys. The eroded sediments accumulated at the foot of the hill, where they promoted a phase of floodplain aggradation. In the Lone Valley this final phase of aggradation occurred at a lower rate in comparison with the Ach Valley. As a result the effect of the drop in base level lasted longer in the Lone Valley, thereby promoting further erosion of the cave deposits. We conclude that the record of Gravettian-aged occupation is variable across the two valleys as a result of natural landscape-scale geomorphological processes.