Classification of buried soils, cultural, and colluvial deposits in the Viking town Hedeby

Objective classification of settlement deposits is a prerequisite for understanding human-environment interactions at habitation sites. This paper presents a novel approach combining a relatively fine-scale sampling strategy, a multimethod geoarchaeological investigation of cores and multivariate statistics to aid in the classification and interpretation of complex and intricately stratified archaeological deposits. Heterogeneous settlement deposits, buried soils, colluvial, fluvial, and fluvioglacial sediments from cores retrieved in the Viking settlement Hedeby were investigated using six cost-effectively measurable geoecological parameters: loss on ignition at 550°C, magnetic susceptibility, contents of stones, artifacts, bones, and charcoal with wood. Principal component analysis allowed identifying variables that would sufficiently describe data and cluster analysis enabled the classification of the materials. As a result, 13 classes were distinguished with a detailed and reliable differentiation of materials of natural and cultural genesis. Based on spatial distribution patterns of the classes, hypotheses regarding land use in the adjacent areas were made: Waste disposal in the valley of Hedeby-brook and metallurgic activities north of it. This approach is valuable for coring-based research at settlements, in particular at tightly managed heritage sites, and for surveys to identify potential excavation sites, whereas the set of variables must be adjusted according to local conditions

Raised bed agriculture in northwest Europe triggered by climatic change around 850 BC: a hypothesis

A sudden decline of solar activity around 850 calendar years BC caused a shift to a cool and wet climate in northwest Europe. Food production suddenly became problematic because of shorter, wetter growing seasons and increased night frost. This climate change triggered innovation and the development of a new agricultural system in continental northwestern Europe: arable farming on raised beds (Celtic field banks) laid out in a more or less checked pattern. This kind of agriculture mitigated the effects of the climate shift by providing better drainage and lessening damage by night frost and thus lengthening the growing season. Once the advantages of this kind of cultivation, soil enrichment and optimum root growth besides the hydrological effects, became obvious it will have been practised on a large scale and introduced when people thought it useful, independent of the local hydrological situation