03 April 2025

Geological Constraints on the Temperature of Melt from Vitrified Hillforts

Talk by Ben Medley

Organised by Aberdeen Geological Society. With AGM and workshop on Geological Interpretation Art by Pheobe Sleathe. Non-members should contact the secretary via online form or via the Communications Officer at communications@aberdeengeolsoc.org.uk

Vitrified hillforts, found across Europe (~230 sites in the UK and beyond), exhibit rock melting (vitrification) through intense fire at surface pressures. The mechanisms and purpose of this vitrification remain unclear—whether accidental or intentional. It is difficult to produce these temperatures in a lab, let alone outside on a huge scale witnessed at these sites. Temperature is key to understanding vitrification. Investigating melt temperature ranges and limitations can shed light on the process. Current research suggests that vitrification does not stem from melting primary building stones but rather from interstitial finer-grained materials, such as soil or glacial deposits. The original fort design may hold clues to these heating conditions.

Ben MedleyBen is a PhD student in geoarchaeology and geochemistry at the University of Aberdeen. He is studying the Iron Age phenomenon of hillfort vitrification from a geological and geochemical perspective.