Anthropic sediments on the Scottish North Atlantic seaboard: Nature, versatility and value of midden

Abstract

Traditionally archaeology has referred to the anthropic sediments accumulated around prehistoric settlements with the blanket term ‘midden’. This is now recognised as an inadequate term to describe the complex formation processes and functions represented in these sediments. This thesis reviewed the body of evidence accumulated over the past century of research into Neolithic and Bronze Age settlements on the islands of the Scottish North Atlantic seaboard and extrapolated the many occurrences of ‘midden’. Several contexts emerged for these sediments including interior floors, hearths, exterior occupational surfaces, dumped deposits, building construction materials and abandonment infill. In addition, ‘midden’ is described added to cultivated soils to form fertile anthrosols. The way in which prehistoric communities exploited this material for agriculture and construction has been described through geoarchaeological research which implied that to past communities ‘midden’ was a valuable resource. This led to the formation of a model based upon a human ecodynamics framework to hypothesise sediment formation pathways. Rescue excavation at the Links of Noltland, Westray provided an opportunity to conduct a holistic landscape and fine resolution based study of Neolithic and Bronze Age settlement to test this model. The research incorporated auger survey, archaeological and geoarchaeological excavation, thin section micromorphology and SEM EDX analyses. Sediments identified in literature review and recovered from the field site were described using this toolkit and set within a cultural and environmental context. Results demonstrate that anthropic materials were incorporated into all contexts examined. Discrete burning and maintenance activities were found to have taken place during the gradual accumulation of open-air anthropic sediments whilst incorporation of fuel residues and hearth waste into floors lead to the gradual formation of ‘living floors’ inside structures. An unexpected discovery was evidence of animal penning within late Neolithic/Early Bronze Age settlement and the in situ burning of stabling waste. Three types iv | P a g e of land management strategy which relied upon the input of anthropic sediments were evidenced and the range and extent of anthropic inclusions in the landscape recorded. Spatial interpolation of auger survey data utilised a new sub-surface modelling technique being developed by the British Geological Survey to explore soil stratigraphic relationships in 3D. SEM EDX analysis supported micromorphological analysis providing chemical data for discrete inclusions and assisting in the identification of herbivore dun ash and the Orcadian funerary product ‘cramp’. SEM EDX analysis was also applied to fine organo-mineral material for statistical testing of nutrient loadings across context groups. It was found that anthropic sediments were enriched in macro and intermediate plant nutrients Mg, P, K, S and Ca compared to geological controls, and the application of anthropic material to cultivated soils improved soil fertility for the three observed land management practices. The versatility of anthropic sediments was explored through discussion of context groups based upon the results of this research and the potential significance of this material to prehistoric communities is explored.