The Relationship between Iron Age Hill Forts, Roman Settlements and Metallurgy on the Atlantic Fringe Keith Haylock BSc Department of Geography and Earth Sciences Supervisors Professor John Grattan, Professor Henry Lamb and Dr Toby Driver Thesis submitted in fulfilment of the award of degree of Doctor of Philosophy at Aberystwyth University 2015 0 Abstract This thesis presents geochemical records of metalliferous enrichment of soils and isotope analysis of metal finds at Iron Age and Romano-British period settlements in North Ceredigion, Mid Wales, UK. The research sets out to explore whether North Ceredigion’s Iron Age sites had similar metal-production functions to other sites along the Atlantic fringe. Six sites were surveyed using portable x-ray fluorescence (pXRF), a previously unused method in the archaeology of Mid Wales. Also tested was the pXRF (Niton XLt700 pXRF) with regard to how environmentally driven matrix effects may alter its in situ analyses results. Portable x-ray fluorescence was further used to analyse testing a range of certified reference materials (CRM) and site samples to assess target elements (Pb, Cu, Zn and Fe) for comparative accuracy and precision against Atomic absorption spectroscopy (AAS) and Inductively coupled plasma mass spectrometry (ICP-MS) for both in situ and laboratory sampling. At Castell Grogwynion, one of the Iron Age sites surveyed recorded > 20 times Pb enrichment compared to back ground values of 110 ppm. Further geophysical surveys confirmed that high dipolar signals correlated to the pXRF Pb hotspots were similar to other known Iron Age and Roman period smelting sites, but the subsequent excavation only unearthed broken pottery and other waste midden development. Broken pottery remains were dated to no earlier than the medieval period suggesting a re-occupation, possibly for Pb prospection. It was established that Pb and metal rich soils within the villa footprint have similar isotope signatures to local ores found ca. 4km east, suggesting local ores were used in its construction, possibly with some evidence of in situ metal working. Key words; pXRF, Iron Age, Roman period, Ceredigion, Pb i Acknowledgements Firstly, I would like to express my sincere gratitude to my mentor, advisor and friend Professor John Grattan for his continuous support for my PhD study. His patience, motivation, immense knowledge, and guidance have helped me during the process of research and compilation of this thesis. I could not have imagined completing this study without his considerable time, support and attention to detail. Besides my advisor, I would like to thank Professor Henry Lamb, Dr Bill Perkins, Dr Toby Driver, Dr Simon Timberlake and Dr Harry Toland for their help, insightful comments, constructive criticisms and continuous encouragement, but also for the hard questions they posed, which encouraged me to dig deeper and widen my learning to complete this thesis. My sincere thanks also go to Professor Russell Adams and Professor David Gilbertson for their considerable field-work knowledge which they imparted to me in Jordan when I was part of the Barqa landscape investigation team without thought of thanks or credit. Working with them gave me a further insight into geomorphology, archaeology and mining contamination all of which was has been fundamental to this thesis. Also, I would like to thank the academics and support staff at the Institute of Geography and Earth Science Aberystwyth (IGES), who have always had the time and patience to encourage me, help me and discuss any questions that often confounded me. I would also thank my fellow cohort, Ian, Erin, Jo, Joe, Vicky, Nathan and Rebecca for the stimulating discussions, constant support, fun and at times shared desperation we have experienced while pursuing our respective PhD’s. I shall cherish the time I have spent with them and look forward to many more discussions and spending time with these exceptional people. Last but not the least I would like to thank my family’s support throughout the time I have spent on this journey of enlightenment. David, Gwenny and Joshua have always encouraged my ambition, but kept my feet firmly planted in reality. But it goes without saying, I am totally indebted to my wife and soul mate Sue, for her bottomless unwavering support, constant encouragement and love, without which, this thesis would not have been possible. For Wendy ii Statement DECLARATION This work has not previously been accepted in substance for any degree and is not being concurrently submitted in candidature for any degree. Signed ...................................................................... (candidate) Date ........................................................................ STATEMENT 1 This thesis is the result of my own investigations, except where otherwise stated. Where *correction services have been used, the extent and nature of the correction is clearly marked in a footnote(s). Other sources are acknowledged by footnotes giving explicit references. A bibliography is appended. Signed ..................................................................... (candidate) Date ....................................................................... STATEMENT 2 I hereby give consent for my thesis, if accepted, to be available for photocopying and for interlibrary loan, and for the title and summary to be made available to outside organisations. Signed …………………………………………………………………. (candidate) Date …………………………………………………………………… iii Funding body and external partners This KESS project has been supported by the European Social Fund through the Welsh Government; The Royal Commission on the Ancient and Historical Monuments of Wales; and Dyfed archaeology iv Table of Contents List of Figures ........................................................................................................................ ix List of tables ......................................................................................................................... xv Chapter 1 ................................................................................................................................... 1 Introduction .............................................................................................................................. 1 1.1 Rationale for site selection ............................................................................................. 2 1.2 Thesis structure ............................................................................................................... 3 Chapter 2 Background .............................................................................................................. 6 Introduction .............................................................................................................................. 6 2.2 Structural geology and mineral assemblages in Mid Wales ........................................... 9 2.3 Mineralisation ............................................................................................................... 14 2.4 Mineral assemblages ........................................................................................................ 16 2.4.1 Sphalerite (ZnFe)S ...................................................................................................... 16 2.4.2 Galena (PbS) ............................................................................................................... 17 2.4.3 Chalcopyrite (CuFeS2) ................................................................................................. 18 2.4.4 Iron ore....................................................................................................................... 18 2.5 Landscape, climate and agriculture .................................................................................. 19 2.6 Climate .............................................................................................................................. 21 2.7 Agriculture......................................................................................................................... 22 2.8 Distribution, architecture and purpose of hill forts .......................................................... 22 2.9 Sites of known metallurgy in mid and north Wales .......................................................... 25 2.9.1. Bronze Age metallurgy .............................................................................................. 25 2.9.2 Iron Age metallurgy.................................................................................................... 32 2.9.3 Roman and medieval period metallurgy .................................................................... 35 2.10 Summary ..................................................................................................................... 39 Chapter 3: Site description ..................................................................................................... 40 Introduction ............................................................................................................................ 40 3.1 Iron Age hill fort and Roman settlement chronology ................................................... 40 3.3 Hill fort and settlement construction and metal lodes ................................................. 41 3.4.1 Pen Dinas (Elerch) ............................................................................................... 44 3.4.2 Odyn Fach (Small or little kiln) ...........................................................................