Isotopes in the landscape

This thesis deals with the development of farming landscapes in the Thames Valley from the Neolithic to the Roman period (4000 BCE – 410 CE). The focus is on the major domestic animal species, cattle, sheep and pig, and their roles in the agroecosystem, traced using carbon and nitrogen isotope ratios measured in collagen. The large dataset of faunal isotope values from a limited area, obtained from sites with extensive archaeological and environmental information, allowed a thorough characterisation of variability in isotope values, within and between species, sites, archaeological periods, and landscape regions. Isotope ratios in a flock of modern sheep showed less variability than archaeological assemblages. Linear mixed models were used to analyse variation in isotope values in 1490 archaeological samples from 23 sites. The pattern of change over time differed for cattle, sheep and pig, reflecting both wide-scale environmental change and changes in animal management. δ13C values of cattle and pigs reflected the loss of primary closed-canopy woodland. Pig management changed from an emphasis on woodland resources to a closer association with settlement and consumption of anthropogenic waste. Herbivore δ15N values probably reflect variations in the intensity of pasture use and association with arable farming. Climatic cooling since the post-glacial thermal maximum cannot explain these varied trajectories of change. Variation between sites in faunal isotope values was related to landscape regions. Faunal isotope values at individual sites were useful in site interpretation in the context of other evidence. The trend in pig and cattle δ13C values with time was widely found in the UK, as expected if it represents forest clearance. In the Neolithic, cattle management was similar to the UK at central and eastern European Neolithic sites, but pig management was different. Patterns of faunal isotope values and their changes over time, analysed in the context of archaeological and environmental information, can contribute to the interpretation of sites, and give a unique perspective on changes in farming practice and their effects on the landscape.