EvAluAting thE uSE of Multi-ElEMEnt Soil AnAlySiS in ArchAEology: A Study of A poSt-MEdiEvAl croft (olligArth) in ShEtlAnd

studies have tended to use multi-element analysis techniques to establish elemental patterns for selected functional areas or across sampling grids covering entire archaeological sites. Spatial patterns have been identified for particular elements, but the outstanding problem is the interpretation of the results. the essential approach has been to establish patterns and then to propose reasons. We are proposing a project that will validate the approach much more robustly by sampling over a range of known archaeological contexts to gain unequivocal insight into the processes contributing to elevated elemental concentrations. different chemical elements can be incorporated into an archaeological deposit via fuel ash, manures and cess, midden deposits, food and crop processing residues, domestic residues, building materials, and industrial and manufacturing waste. previous studies have suggested that phosphorus (p), lead (pb), zinc (Zn), copper (cu), cadmium (cd), magnesium (Mg), manganese (Mn), calcium (ca), titanium (ti), rubidium (rb), strontium (Sr), potassium (K) and barium (Ba) may all be potentially useful elements for archaeological interpretation (e.g. lewis et al., 1993; linderholm & lundberg, 1994; Middleton & price, 1996; Entwistle et al., 2000; Wells et al., 2000; parnell et al., 2002). Aston et al. (1998) interpreted signatures of p together with high concentrations of Zn, cu and pb as evidence of faecal material, and p with high levels of Mn and to a lesser extent Zn as wood and wood ash residues based on the results of analysis of modern materials. however, environmental and dietary differences are likely to have significant effects on the element composition of vegetable and faecal material. Although there have been few studies of this kind, studies of modern human and animal faeces, wood, and fuel ash (Aston et al., 1998; pierce et al., 1998) have shown that no one element can be related to a particular activity or material. instead it is the relative concentration of many different elements that produce a chemical «signature». the extent to which any element will become concentrated in soil depends upon the nature, duration and intensity of the polluting activity, and of the disposal process. interpretation may be complicated, however, as materials are moved around the site and become mixed, before finally being deposited. once in the soil, postdepositional pedogenic processes – including leaching, weathering, waterlogging, podzolisation, bioturbation, and surface vegetation – will affect the retention and