Charcoal assemblages occur in both natural and archaeological settings. Cell wall reflectance values of charcoal in polished blocks under oil provide a proxy for temperature of formation. This paper aims to (1) determine whether wildfire charcoals and anthropological charcoals from various pyrotechnical activities can be distinguished using reflectance data and (2) establish if re-charring (i.e. use of charcoal fuel) can be recognised in the archaeological record through analysis of laboratory-produced re-charred charcoals and charcoals from an experimental iron smelt and traditional bronze casting which utilised charcoal fuel. Reflectance frequency data from assemblages representing burning of charcoal, in this case of iron smelting and bronze casting, indicates temperatures from above the mean value of charcoal production (>475°C) up to the maximum temperature reached in the subsequent process (i.e. >475 to >1,100°C). In contrast, wildfire charcoals showed a range of values including material with barely measurable reflectance (minimum values from 0.06% to 0.56%Ro) to maximum reflectance values varying from 1.65%Ro (Tilford) to 3.8%Ro (Zacca). The mean wildfire reflectance indicated temperatures in the range 325-400°C, which can therefore clearly be distinguished from that of the charcoal burning processes. The laboratory-produced re-charred charcoals take on the reflectance value of the highest temperatures experienced; reflectance values were not constrained by the original temperature of formation. High temperatures are most easily achievable by the burning of charcoal fuel, and hence high reflectance charcoals are likely to represent re-charred charcoal. Therefore, this quantitative reflectance method can be used in archaeology to determine the minimum temperature of formation of charcoals in anthropological processes which involve fire, can indicate the likelihood of use of charcoal or wood as fuel and can distinguish between an assemblage of high temperature anthropogenic charcoals and charcoals formed from natural wildfire.

No abstract

While conducting a review of published archaeobotanical remains from southern and central England, it became apparent that contamination (intrusion and residuality) was a notable, recurring theme in many assemblages. This problem is most acute in some key periods in which plant assemblages are generally less abundant than in others, such as the Neolithic and the early medieval (Saxon) periods. While most archaeobotanists are aware of the potential for contamination, without direct dates it is often difficult to demonstrate and it is likely to have obscured the true patterns in the data. Contamination becomes particularly problematic once poorly or incorrectly phased data enter the secondary literature. A number of case studies are presented, including newly dated material from a high profile excavation at Durrington Walls, Wiltshire. The importance of direct dating of plant remains is discussed.

Following the Roman conquest, agricultural production in Britain faced increasing demand from large urban and military populations. While it has long been thought that this necessitated an increase in agricultural production, direct archaeological evidence for changes in cultivation practices has been scarce. Using a model that conceptualises cereal farming strategies in terms of intensive or extensive practices, this paper is the first study to address this question using carbon and nitrogen stable isotope data of crop remains. We report δ 15 N and δ 13 C values from 41 samples of spelt, emmer and barley from Bronze Age, Iron Age and Roman Stanwick (Northants., UK), in order to assess the intensiveness of arable farming and investigate shifts in cultivation practices in prehistoric and Roman Britain. The results demonstrate a decline in δ 15 N in the Roman period, suggesting that farming practices moved to lower levels of manuring and, by implication, became more extensive. δ 13 C values are comparable in all periods, supporting the suggestion that changes observed in human stable isotope data between the Iron Age and Roman period are best explained by dietary change rather than a shift towards higher δ 13 C values in plants at the base of the food chain.

No abstract