Project Description
Vitrified hillforts, whose walls have been destroyed by the melting and fusing of outer rock walls through fire, are found throughout Europe, with a significant concentration occurring across Scotland. Those specific to Scotland have been dated from the Bronze age to early Medieval period, suggesting a long-cultural significance to fort vitrification. The circumstances and methods involved in the vitrification of hillforts, however, remain heavily debated.
The process of rock vitrification requires a considerable understanding of fire technology, in order to get temperatures capable of melting rock in pervasive temperatures exceeding 1000°C, with the outcome being a mineral ‘glass’. In contrast, achieving these temperatures in contemporary settings requires complex equipment and experimental processes. This raises considerable questions as to the possibility, means and aims of fort vitrification in early European history. An interdisciplinary application of earth science analyses – including rock geochemistry, Raman spectroscopy, and palaeoecology – offers a unique opportunity to investigate how and why fort vitrification was achieved. To answer this, the project will be divided into two main parts.
The first component of the studentship will involve identifying and sampling rock, vitrified glasses, and charcoals from two different hillforts (one in Scotland, and the other in Europe). Rock and glass samples will be used to conduct mineral analysis to understand changes in rock chemistry during vitrification, and olivine geothermometry (calculating temperatures of melt from olivine cooling rates). Charcoals, encased within the glass, will be analysed using Raman spectroscopy to calculate the temperatures experienced during the fires. This research will also involve extensive application of the new scanning electron microscope in the School of Geosciences, University of Aberdeen. Comparing and calibrating these methods will help understand and develop new methods of geothermometry, specific to hillfort vitrification.
The second part of this project will include sampling soil and/or peat from the environs of each hillfort to identify potential windblown charcoals and pollutant geochemistry that may correspond to the vitrification event. Charcoals and peat/soil chemistry will then be analysed, alongside pollen and macrofossil study, to quantify the types of fuels and accelerants that may have been used during vitrification. These data will offer insight into how hillfort sites, separated geographically and culturally, were vitrified using different fuels, rock types, and environmental conditions.
Throughout this project, the student will undertake a mix of fieldwork (UK & International) and laboratory work – including Raman spectroscopy, light microscopy, scanning electron microscopy, and gas chromatography-mass spectrometry (all training provided). Desirable skills include good experience in any microscopy, and a comfortability with computer-based data processing.
Essential & desirable candidate skills
Essential: Strong background in either geology, chemistry, biology, or archaeology.
Desirable: Good experience with microscopy, geochemistry, and computational data processing (e.g. Excel)
Supervisors
Malcolm HolePrimary Supervisor: | Profile: Malcolm Hole Email: m.j.hole@abdn.ac.uk Institution: University of Aberdeen Department/School: School of Geosciences |
Maarten BlaauwSecondary Supervisor: | Profile: Maarten Blaauw Email: maarten.blaauw@qub.ac.uk Institution: Queen's University, Belfast Department/School: School of Natural and Built Environment |
Gordon NobleAdditional Supervisor: | Profile: Gordon Noble Email: g.noble@abdn.ac.uk Institution: University of Aberdeen Department/School: School of Geosciences |
David MuirheadAdditional Supervisor: | Profile: David Muirhead Email: dmuirhead@abdn.ac.uk Institution: University of Aberdeen Department/School: School of Geosciences |
Dmitri MauquoyAdditional Supervisor: | Profile: Dmitri Mauquoy Email: d.mauquoy@abdn.ac.uk Institution: University of Aberdeen Department/School: School of Geosciences |
Additional Supervisor: | Mr. Thomas Theurer University of Aberdeen, School of Geosciences Email: t.theurer.19@abdn.ac.uk |
References
Smith, D. C. and Vernioles, J. D. (1997), The temperature of fusion of a Celtic vitrified fort: A feasibility study of the application of the Raman microprobe to the non-destructive characterization of unprepared archaeological objects. Journal of Raman Spectroscopy, 28, 195-197. doi: 10.1002/(SICI)1097-4555(199702)28:2/3<195::AID-JRS86>3.0.CO;2-A
McCloy, J. S., Marcial, J., Clarke, J. S., Mostafa, A., Wolff, J. A., Vicenzi, E. P., et al. (2021). Reproduction of melting behavior for vitrified hillforts based on amphibolite, granite, and basalt lithologies. Scientific Reports (Nature Publisher Group), 11(1). doi: 10.1038/s41598-020-80485-w
Theurer, T., Naszarkowski, N., Muirhead, D. K., Jolley, D. and Mauquoy, D. (2022). Assessing modern Calluna heathland fire temperatures using Raman spectroscopy: Implications for past regimes and geothermometry. Frontiers in Earth Science, 10, 827933. doi: 10.3389/feart.2022.827933
Research Methods
Throughout this project, the student will undertake a mix of fieldwork (UK & International) and laboratory work – including Raman spectroscopy, light microscopy, scanning electron microscopy, and gas chromatography-mass spectrometry (all training provided). Desirable skills include good experience in any microscopy, and a comfortability with computer-based data processing.
Impact
Hillfort vitrification represents a pervasive feature of early settlement fortification worldwide – suggesting a strong cultural significance. Whilst theories as to the circumstances surround this, complex questions remain as to the drivers, circumstances, and means by which vitrification was achieved. Answering these questions may reveal considerable insights into otherwise unknown rituals and tactics of an ancient population. The methods in application – particularly Raman spectroscopy – have shown considerable applicability in substantial contemporary issues such as wildfire regimes and soil-carbon fluxes. The nature of this project will complement, develop, and refine novel earth science equipment and protocols – contributing to significant research topics in a truly interdisciplinary way.
Proposed Timetable
Year 1 will involve surveying, sampling, and geochemical analyses of solid rock material from two hillfort sites, alongside an extensive literature review. Geochemical analyses will continue into Year 2, accompanied by sampling and analysis of soil and peat materials for palaeoecological study. Year 3 will incorporate continued palaeoecological analysis with experimental replication of vitrification conditions.
