METHODOLOGICAL DEVELOPMENTS FOR THE GEOCHEMICAL ANALYSIS OF OCHRE FROM ARCHAEOLOGICAL CONTEXTS: CASE STUDIES FROM BRITISH COLUMBIA AND ONTARIO, CANADA

Abstract

Ochre is a culturally significant material that is commonly recovered from archaeological sites. However, despite its ubiquity it has yet to realize its full interpretive potential as an artifact of archaeological inquiry, specifically in the context of geochemical characterization studies. Studies of this type, often referred to as ‘sourcing’ studies, involve the application of techniques in radiation physics to determine the elemental composition of artifacts and raw materials. These data are then used interpret patterns of behaviour in the procurement, movement, and trade of different artifact classes such as obsidian, chert, or ceramic. By comparison, geochemical characterization studies centred on ochre-related activities are fewer in number.

This thesis consists of three case studies that developed methodological foundations for the geochemical study of ochre in regions of British Columbia and Ontario, Canada, respectively. Using instrumental neutron activation analysis and X-ray fluorescence, ochre from geologic outcrops and archaeological sites were analysed to determine their elemental composition. Multivariate statistical tests, including principal components and canonical discriminant analyses, were conducted to explore patterns and variability in ochre geochemistries. The results described in the following papers demonstrate the challenges and limitations for characterization studies of ochre, and present considerations for expanded research in these geographic regions. This thesis offers contributions to broader topics of discussion in archaeological sciences, such as the accurate and precise acquisition of geochemical data, the role of geologic scales and diagenetic processes on the chemistries of iron oxides, how to identify and interpret patterns in elemental data sets, and the utility and limitations of portable analytical technologies.

This research has established important methodological foundations for the study of ochre in British Columbia and Ontario, and has demonstrated the potential for expanded analysis of materials from additional archaeological sites and geologic outcrops. This will enable the future interpretation and regional synthesis of patterns and networks of ochre-related activities, including quarrying and procurement, trade and exchange, and variability in use contexts.