A geoarchaeological study on two Norwegian boat graves : Soil analysis and an attempt of forensic work strategy and thinking in the interpretation of the results

Abstract: The following paper is the final thesis of two years long experimental work conducted on two different collections of soil samples coming from two different Norwegian archaeological sites. In particular, the first collection of soil samples comes from an identified boat grave from the Viking Age (eg Sykehus area Kristiansand County, Vest-Agder). The second one comes also from a boat grave from Vestfold region in Hejmdaljordet archaeological site. Both the collections of samples have been analysed with geochemical methods (phosphate extraction and determination, magnetic susceptibility and loss on ignition), NIR (Near-InfraRed) spectroscopy and X-ray fluorescence. Although the contexts are different, a comparison between them has been attempted. In particular, the first boat grave presented a very altered and spoiled conditions because of different disturbance actions coming from atmospheric factors but also human actions such as looting or burning, that have not permitted the discovery of significant archaeological findings. Conversely, the second boat grave presented more favourable conditions and also a discrete preservation. In fact, it was possible to recover the belongs of the dead, such as fragments of the belt, a sword and the rivets surrounding the boat. Thanks to the wide series of analysis conducted on soil samples and to an accurate comparison between the two boat graves, it has been possible to detect the presence of high concentration of organic matter (eventual presence of the human body), a high level of magnetic susceptibility (eventual presence of metallic components detected in the soil), detection of specific chemical elements in the soil that could attest the eventual presence of items within the graves and finally, a general report of the possible anthropological impact by the light spectra measurements, through the use of spectroscopy. All the results collected have been interpreted using a forensic work strategy which concerns the detailed analysis of anomalies found in the soil texture and chemical composition. Further, a significant number of tests that could prove the presence of human body in the grave and the eventual reasons of the bad preservation and lack of archaeological (most in the eg Sykehus case) information detected in the context (disturb actions represented by looting and burning). Finally, a series of maps have been created to show with clearness the results of the study.