Patricia Vandorpe

Comparing different pre-treatment methods for strongly compacted organic sediments prior to wet-sieving: a case study on Roman waterlogged deposits

Abstract Four pre-treatment methods have been tested on strongly compacted organic sediments prior to sieving. They comprise heating, freezing, soaking in NaHCO3 (sodium bicarbonate) and heating with 10% KOH (potassium hydroxide). The aim of the experiment was to find out which pre-treatment method facilitates the sieving process without destroying the waterlogged plant remains recovered. Several methods are already described in the literature, but only few systematic comparisons of pre-treatment methods were undertaken. Of the four techniques tested, freezing the samples prior to sieving came out as the best option; it eases sieving and has the least damaging impact on the waterlogged plant remains. In addition, it is fast, uncomplicated and does not leave any chemical waste.

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’.

Food plants in anthropogenic sediments as represented in pollen and macrofossil spectra: a case study on waterlogged Roman sediments from Switzerland and Alsace, France

The present study combines results of pollen and macrofossil analysis to examine the preservation of food plants in on-site archaeological deposits from various Roman waterlogged sites in Switzerland and Alsace (France). Through the integration of pollen and macrofossil analysis a much wider range of food plants is recorded, and it is clear that the plant spectra of both proxy data sets are complementary. The combined analyses enables new insights into food consumption and preparation, and issues of local cultivation and/or the import of food plants can be approached.