Identification of activity area signatures in a reconstructed Iron Age house by combining element and lipid analyses of sediments

One promising analytical method used in household archaeology in addition to inorganic (element) geochemical analysis is that of organic (lipid) analysis applied to anthropogenic sediments. We use both methods here to review chemical imprints that might be useful for recognizing space use and identifying daily activities in a reconstructed Iron Age village at Lejre, Denmark. As documented in many previous studies, element analysis enabled separate activity areas to be distinguished, but the results could not be used to identify the specific activities pursued in the areas. A more qualitative identification of activity areas was possible through lipid analysis, however. The carbon chain distribution, studied for Average Chain Length (ACL), Carbon chain Diversity Index (CDI) and Carbon Preference Index (CPI), enabled a similar separation to be achieved as by element analysis, so that the same areas could be discerned in addition to the reference samples. The stable was distinguished by a substantial input of coprostanol and even more so by 24-ethylcoprostanol, indicating a faecal input from herbivores. Trace levels of these markers were also identified at the entrance, where the animals had passed through. The dwelling area, consisting of two adjacent rooms, could be identified by the sterol ratio (cholesterol/[stigmasterol + β-sitosterol + campesterol]). Lipids from an archaeological context have decayed further toward simpler compounds and become more difficult to identify. Some markers have however a better potential for survival. The results emphasize the importance of further studies on ethnoarchaeological material in order to recognize past activities by element analysis. Moreover, the combination of element and lipid analyses provided a tool that enabled all the separate areas to be identified and provided positive identification of the activities concerned in all areas except the smithy.