Evaluating the use of multi-element soil analysis in archaeology: a study of a postmedieval croft (Olligarth) in Shetland

Abstract

Multi-element soil analysis is an established technique in archaeology, but there has been little work to understand the processes and loadings involved. The abandoned farm (croft) of Olligarth, Shetland provided the opportunity of validating the technique by sampling from known contexts. The results showed multi-element soil analysis could accurately differentiate between areas of known function. Accuracy was increased using samples from the floor layers rather than topsoils. The elements that produced the best discriminant model of function were P, Ca, Cr, V, Fe, Nd, Ti, Pb, Al, and Yb. However because of cross-correlation between elements, Cu, Zn, Sr, Ba, K, Mg, Mn, Na, Ni, Co, Ni, and the rare earth elements, were also important potential discriminators. Of these P, Ca, Zn, Sr, Pb, Cu, Ba, Na, K, and Nd correlated positively with soil CEC and organic matter content and may, in part, originate from fuel materials, plasters, dung and bone. Ti, Cr, Al and many rare earth elements were influenced by local geological variation and are of less interest archaeologically.