Micromorphological and chemical investigation of late-Viking age grave fills at Hofstaðir, Iceland

•Complex relationships occur between inhumed human remains and their grave fills.•Weathering of volcanic silicates in grave fills can be affected by the human remains.•Point counting can effectively assess volcanic silicate weathering in grave fills.•Organic chemical signatures provide evidence for the former presence of a coffin.•Non-native wood indicates either foreign lumber import or driftwood utilization.

Grave fills from seven human burials from a late-Viking age - early medieval cemetery at Hofstaðir, Mývatnssveit (Iceland) were examined by soil micromorphology and organic chemical analysis. Detailed analysis of the weathering of the mineral constituents of the grave fills demonstrates a relationship between the extent of weathering of volcanic silicates within the fills and the presence of buried human remains. Gas chromatography-mass spectrometry (GC-MS) of extracts from the fills and controls of two graves revealed organic signatures dominated by plant-derived organic matter, with no evidence of degradation products of the body tissues. Transformation of n-alkanes into n-alkan-2-ones provides evidence for microbial activity within the fills. GC-MS analysis of the organic extract from under one of the skulls and pyrolysis gas chromatography of wood fragments found in that grave provide compelling evidence for the former presence of a conifer wood coffin. The use of this non-native wood in the burial provides evidence for either the import of foreign lumber or the utilisation of driftwood, most likely originating from Russia/Siberia.