Layers rich in aquatic and wetland plants within complex anthropogenic stratigraphies and their contribution to disentangling taphonomic processes

There is an ongoing discussion about how organic material is preserved in settlement layers on lakeshores. Different scenarios have been suggested; was a permanent water cover needed at all times, or were there episodical water level fluctuations? In this paper, we use aquatic and wetland plants to shed light on layer formation processes of complex anthropogenic stratigraphies of the Neolithic lakeshore settlement Zug-Riedmatt (Central Switzerland). Botanical macroremains from the microarchaeologically investigated occupation layer were analysed and compared to modern analogue data from two lakes. Results suggest that the excavated area of the settlement was in a first phase located in the sublittoral zone (below water), with a massive input of anthropogenic waste material contributing to the layer formation, but then in a second phase, the shoreline shifted so that the excavated part of the settlement was located in the eulittoral zone and in a third phase probably even landwards of a reed belt. In a comparison with two previously investigated Neolithic lakeshore sites, we found that at least in one of these sites, such ‘drier’ conditions could also be found. This shows how important it is to know which part of the littoral zone is represented in an excavation, as conditions can differ within a settlement, and that there is very likely no universally valid ‘Pfahlbau scenario’.