Viking Age Ribe was surrounded at some point in time by considerable defences consisting of an earthen rampart and a c. 20 m wide, shallow moat. The earthworks extended over more than half a kilometer, representing one of the most formidable defensive structures known from the Viking Age in Scandinavia. As a major building work and a physical demarcation of the urban area, the rampart has been a pivotal point in discussions of the evolution of Scandinavia’s earliest town. The possible presence of major defences contemporary with the early trading-port would be the earliest recorded case of a town wall in Scandinavia, and a major challenge to the general view of early Ribe as open, rather weakly institutionalized community. However, the dating of the moat was based on object finds, individual stratigraphic relationships, and could not be pinned down more closely within a period from c. AD 850-1000.
The Ribe Rosenallé Excavation project has targeted the moat, aiming to establish the chronology of the structures more exactly. For the first time, a wide stretch of the rampart was uncovered, enabling us to study the lay-out of the moat, and to establish that no major wooden constructions had formed part of the moat or rampart. A consequent stratigraphic excavation procedure allowed us to obtain an un-mixed artefact collection from the fill of the moat, comprising several coins and other well-dated artefacts, which make it clear that the moat was filled in by the mid-eleventh century at latest.
In order to date the construction of the moat, other methods were required. With the collaboration of UrbNet’s Geoarchaeological team samples were obtained from a thin layer of humic soil in the moat bottom, the remains of a short-lived vegetation cover. Using a method developed by the AMS dating Centre of Aarhus University, organic matter of the buried former soil surface was submitted to acid-alkali-acid fractionation of soil organic matter (SOM), and subsequent 14C AMSdating. The results were analyzed together with those of conventional 14C-dates on charred seeds and twigs from the floor of the moat and subjected to Bayesian statistical modelling.
The results have major and surprising implications for the re-construction of early urban history in the North. It is clearly demonstrated that the major defences were not constructed in the ninth century, when Ribe was first active as a trading port, but only appeared in the tenth, at a time when few other features have been identified, and the town is commonly assumed to have been partly deserted. The rampart now marks a major phase of activity, which was previously practically unknown, and can be associated with a decisive new turn in the urban development. The context and implications of these new realizations are a major goal for continuing fieldwork to elucidate.