Prehistorische branden op Groningse kwelders
Prehistoric fires on Groningen salt marshes. Dark horizons in clay soils around the town of Groningen in the north of the Netherlands have until recently been described as vegetation horizons. Excavations have shown the association of these horizons with archaeological deposits dating from the Iron Age and the Early Middle Ages. During these excavations, as well as during augering surveys, thin black layers of charred material were found in connection to the vegetation horizons. Systematic micromorphological analysis of both the vegetation horizons and the under- and overlying clay, has shown that the thin layers of charred material, as well as the vegetation horizons, reflect the annual burning of the vegetation of salt marshes. It seems most likely that the purpose of this burning was to improve grazing conditions for livestock. Future dating of individual deposits of these fires, as well as identifying the exact species of plants that were burned, will shed more light on the early exploitation of the salt marshes, probably even as far back as the Bronze Age.