Application of mineral magnetism in Atlantic Scotland archaeology 1 : techniques, magnetic enhancement and the identification of fuel sources.

Abstract

Natural and archaeological deposits tend to contain mixtures of magnetic grains of differing 1) concentrations, 2) domain states (linked to grain size) and 3) mineralogies. Many laboratory based magnetic measurements are available to study these attributes. Fire ash is a significant component in the formation of archaeological deposits in Atlantic Scotland and its magnetic enhancement means it is easily identified and traced. Several magnetic techniques were developed from which different types of fuel ash could be identified. The techniques were successfully applied to archaeological samples from the Western and Northern Isles of Scotland. The results show a uniformity in the use of well-humified peat as the major fuel source on Lewis, whereas considerable variability in fuel types was observed at Cladh Hallan, South Uist and Old Scatness Broch, Shetland.