Dehydration, bioturbation and a tree windthrow – the case study of the draining wetland site of Burgäschisee‐Nord (Switzerland)

The Neolithic wetland site of Burgäschisee-Nord is located on the shore of a small lake in Central Switzerland. This site has already been discovered in 1877 and until 1945 repeatedly been investigated. The most recent excavations took place in 2015/2016 within the interdisciplinary SNF-Project “Beyond lake settlements: Studying Neolithic environmental changes and human impact at small lakes in Switzerland, Germany and Austria”. While the existing documentation of the older excavations speaks of extremely well preserved organic remains, the most recent excavations show archaeological layers in danger of total loss. All trenches show signs of dehydration and most layers are disturbed by cracks and bioturbation – results of the lowering of the lake level. Additionally, in some trenches the archaeological activities of the beginning of the 20th century have destroyed all archaeological strata. In others we observed minor destructions by recent construction work and one case of severe disruptions by a treefall. The archaeological evidence of Burgäschisee-Nord shows at least six periods of occupation documented by stratigraphic observations, typological analysis and dendrochronology. At least two areas of prehistoric settlements can be distinguished. This essential site today is under threat of total loss. For exceptional site the question of long-term preservation and sufficient documentation must urgently be addressed.