Phase 1: Cultural innovation and transmission: Project 012|
How does metallurgical innovation explore the space of chemical possibility?
SUPERVISOR: - Stephen Shennan and Thilo Rehren (Prof of Archaeological Science)
Mike Charlton (Institute of Archaeology, University College London)
PROJECT FUNDING: UCL Research scholarship
Overseas Research Scholarship
The goal of this study is to construct a portion of the evolutionary history of ironworking technology in North-West Wales. This involves the investigation of technological variation in terms of engineering design constraints, environmental adaptations, drift, and mechanisms of cultural transmission. Models and hypotheses derived from neo-Darwinian evolutionary theory provide the basis for identifying and explaining these sources of variation. All archaeological evidence comes from three sites excavated by Peter Crew: Crawcwellt West (300 BC—AD 50), Bryn y Castell (150 BC—AD 250), and Llwyn Du (14th century AD). This, combined with data sets from a linked series of experimental smelting campaigns, provides ample material evidence to begin building and explaining ironworking lineages. The materials used for this study include iron production wastes (smelting and smithing slags), unused or discarded raw materials (ore, charcoal, and clay), and furnace remnants. Bulk chemical analysis of slags and raw materials by x-ray fluorescence spectrometry (XRF) comprises the primary source of data generation, with supplemental evidence stemming from phase analyses by optical and scanning electron microscopy.
Analysis of smelting slag has allowed me to construct lineages for both the Bryn y Castell and Llwyn Du archaeological samples. Both exhibit changes that correlate closely with known historical events. Archaeological evidence points to a hiatus (approximately AD 50—AD 150) in iron working at Bryn y Castell following the Roman conquest of north Wales. Crew has previously argued that Roman prohibition, rather than decimation of ironworkers or overexploitation of environmental resources, likely causes this cessation. Preliminary analysis of slag suggests that the knowledge for smelting iron was still transmitted during the interruption to activity, although with reduced fidelity. Reasons for this loss of knowledge (and/or gain of spurious knowledge) could include the lack of actual practice as a transmission mechanism and a change in selective context for ideas about iron smelting. Preliminary explanations for the Llwyn Du lineage suggest that the fourteenth century iron industry in Wales enjoyed relative stasis in overall performance, but was severely disrupted by a period of forest degradation.
Sampling materials from all sites and experimental smelts is complete and I plan to spend the next six months in the laboratory preparing and analyzing new specimens of slag and other ironworking artefacts. At the end of April I will be a participant at the Metallurgy - A Touchstone for Cross-cultural Interaction conference being held at the British Museum. I am second author on two papers: Peter Crew and Michael Charlton—Anatomy of a Furnace; Thilo Rehren et al.—The human factor in African iron slag: variability, homogeneity and the role of choice. In July, I will present a paper at the International Medieval Congress in Leeds with the provisional title: The Technology and Economics of Iron Smelting in 14th Century Wales.
Other future activities include participating in further experimental smelting campaigns organized by Peter Crew and continued fieldwork at Llwyn Du.