Magnetic geophysical prospection on prehistoric iron production sites in cultivated contexts
Channel: Recording Archaeology
Date: 2016-08-16

In 2010 Hedmark County Council uncovered ten furnaces at two sites, dated to the Merovingian period (600–800 AD) in a cultivated field at Ånestad, Løten, Hedmark. In 2015 the Museum of Cultural History conducted excavations of the sites. In a preliminary phase a geophysical survey was completed, using topsoil magnetic susceptibility mapping and gradiometer surveys, to clarify the extent of the production sites. The geophysics resulted in many anomalies interpreted as possible furnaces. While several proved to be furnaces, a range of geophysical anomalies proved to be of a quite different nature (stones, clay, etc.) when compared with the excavation evidence. In this paper we will discuss what was done methodically and present our experiences on how the geophysical data were put to use and affected the strategy of the excavation, as seen both from the geophysical surveyors and the excavator’s point of view. We will also discuss how the archaeological feedback helped altering the initial archaeological interpretation of the geophysical data, and potentials and pitfalls associated with such a cross-disciplinary collaboration. Finally, we will see this survey from a heritage management and planning perspective, and discuss the value of the geophysical prospecting opposed to the “regular” survey of the County Council. Did the magnetic geophysical surveys contribute with additional data preliminary to the field work at this site? And generally; is more methodical work needed before geophysics is applicable in rescue archaeology of similar sites? We believe the Ånestad–results will act as a contribution to further refinement of the field methodologies and improved understanding of magnetic geophysical data of similar sites in the future.

Christian Løchsen Rødsrud, Arne Anderson Stamnes, Kristin Eriksen