AnthroSOIL · Signatures in Anthropological SOILs: Developments for the identification of activities associated with daily life

Signatures in Anthropological SOILs: Developments for the identification of activities associated with daily life

A wide range of human activities have direct influences on the formation and transformation of soils and sediments. Whereas highly invasive activities such as farming, construction and disposal of waste can be widely recognised in the archaeological record, less invasive activities such as food preparation, animal husbandry and crafts may produce highly localized anthropogenic signatures, some of which are only recorded at the molecular level. By sampling at high spatial resolution we can use chemical and molecular analysis of signatures preserved in archaeological soils associated with occupied spaces to resolve questions about their use. The AnthroSOIL project had two principal objectives: (i) to develop a new methodological approach for the organic analysis of palaeosoils and (ii) to investigate activity patterns within Stonehenge World Heritage site. The strategy adopted was to characterise and map the organic contents of soils at the Late Neolithic settlement of Durrington Walls in Southern Britain. The site was occupied, in total for less than 50 years, around 2500 BC and was probably used to house and sustain the builders of nearby Stonehenge. During recent excavations several houses with intact floor layers and associated midden deposits were discovered and were intensively grid sampled. During the Anthrosoil project, we determined the organic contents of about 500 soil samples. We conducted a range of organic residue analyses from elemental analysis (elemental carbon, nitrogen and total organic carbon) to molecular and isotopic characterisation of lipids (GC, GC-MS and GC-c-IRMS). The quantified results were mapped using geographic information systems (GIS) to examine the spatial distributions of the signatures and results from statistical analysis. The efficiency of the methodology employed has allowed analysis of a large number of samples and recovery of lipid signatures even when the quantity of sediment sampled was low. The analyses have revealed high contents of carbonate which may have contributed to the alteration of complex esterified lipids such as acyl lipids, to form bound lipids that cannot be extracted using the usual solvent extraction methods. We developed and applied a one step in-situ acid extraction method to solvent extracted samples to recover bound residues. Results reveal that complex mixtures of organic matter are preserved in the soils. The signatures reflect both the human activities and the nature of the environment. The organic signatures within the midden represent mainly vegetal matter with discrete areas presenting signatures of the deposition of animal food waste and manure. From recurring patterns in the distributions of the organic signatures we can recognise some consistencies in the use of space within the houses. Lower amounts of organic matter were recorded on the central plastered area of the floor than at the edges of the houses, indicating circulation or regular cleaning in this functional central area. A very low concentration spot was systematically observed next to fire hearths, most likely indicating the presence of an object (or individual) obstructing deposition of residues. Moreover, differences in the organic signatures in the floors permit demarcation of areas of activity relating mainly to cooking and food preparation. The homogeneity in the signatures within the house floors and the ensuing interpretations of living habits bring new insights on the people living in this part of the henge; they seem to share similar habits and, by inference, similar status. The results will be integrated with the other studies conducted at Durrington Walls and Stonehenge to understand the complex relation between domestic and communal areas. The project provided the opportunity for the researcher to broaden his skills and perspectives through engagement with a broad range of analytical techniques in lipid and stable isotopic analysis, to enhance his visibility through attending several conferences and seminars and to increase his network and create new collaborations. The project has provided the methodological ground work for the application of soil organic analysis of archaeological preserved housefloors and will act as a platform for future grant applications involving programmed and preventive archaeological excavation.

Data: CORDIS, © European Union