The Bronze Age fortification of Bernstorf (Upper Bavaria, Germany) - An integrated geoarchaeological and micromorphological approach to reconstruct the genesis of the archaeological site and its prehistoric soils

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The burnt Bronze Age fortification of Bernstorf is known to be one of the largest Bronze Age fortifications north of the Alps. The site has obtained exemplary status due to its entirely burnt fortification of 1.6 km length and the much-discussed gold and amber objects. It belongs to the numerous prehistoric vitrified forts in Europe. Already in the 18th century possible theories for burning of defense constructions circulated. Apart from the fortification burnt remains of Bronze Age houses were discovered. The complex history of the archaeological site with its burnt structures and a settlement sequence stretching from the Bronze to the Iron- and Middle Ages is supplemented by a geoarchaeological approach to detect temporal and spatial anthropogenic changes in the soils. The project aims at 1) investigating the burnt Bronze and Iron Age structures and the experimentally burnt reproduction of the fortification. 2) The genesis of the prehistoric soils and occupation layers should be reconstructed and specific areas of settlement activities differentiated. 1) It is surprising that so far sediments exposed to high temperature were neglected as a by-product of fire use, although they are always present. They offer opportunities to reconstruct past human fire activities and identify pyrotechnological processes. By using a micromorphological and petrographical approach we are theoretically able to distinguish different fire regimes, heat treatment and related application areas which can more specifically be termed as warfare, hearth or production processes. Research on burnt soils and sediments of the fortification has turned out to be an invaluable means for investigating burning temperatures, as it displays a temperature zoning with various heating features. These features are recognizable in thin sections and suitable for the development of micromorphological criteria to identify the burning temperatures. The results will be used for the characterization of the burnt Bronze and Iron Age structures in Bernstorf. In addition to the micromorpholoigical studies x-ray diffraction, magnetic susceptibility analyses etc. will be applied. 2) Long-term human impact distinctly altered the soils in the fortification of Bernstorf. Cambiosols were replaced by colluvisols which include different phases of colluviation. In order to stratify the prehistoric soils, layers and horizons will be described as well as palaeo surfaces, occupation layers and areas of specific settlement activity are likely to be identified. Occupation layers protected by the burnt layers will be treated according to standard laboratory analyses (pH, soil organic matter, texture, total phosphate etc.). These methods will also be used on the sediment remains from the gold and amber artefacts to determine composition, micro structure and pedofeatures. If successful, the results might open up new insights into history, origin and age of the objects.