Straddling the north-west frontier of the Roman empire, this much-needed account is the first to examine the geological character and source of the stone used to construct Hadrian’s Wall. Largely recorded and written during the COVID epidemic, this very well written and illustrated interdisciplinary volume was made possible through lottery funding and the work of the Hadrian’s Wall Community Archaeology Project (WallCAP).
This collaborative project involves the expertise of the eminent community geologist Dr Ian Kille, and key academic/research staff from the Department of Archaeology at Newcastle University (Dr Rob Collins) and Edinburgh University (Dr Kathleen O’Donnell). Indeed, the latter’s PhD focused on ‘The Quarries of Hadrian’s Wall involving thin section and non-destructive geochemistry (PXRF) techniques’.
As well as examining the petrological character and geological source of the stone (sumptuously illustrated with 24 coloured thin sections in an appendix of sampled sites), the project sought to increase our knowledge and understanding of the construction of Hadrian’s Wall from a wide range of different perspectives. This it has achieved in chapters on the extraction process and tooling at the quarry face (Ch. 4), building styles and repair (Ch. 3) and post-Roman reuse of the wall stone (Ch. 5) in an easy-to-read narrative with enough detail to satisfy the needs of the casual reader, archaeologist and geologist alike.
For the non-specialist, the start of Ch. 2, ‘The Geology of the Wall’, provides a clear, useful introduction to the bedrock including an explanation for sandstone colour change in different parts of the wall, ably supported by a geological and architectural glossary at the front of the monograph. The remainder delves very much into the detailed stratigraphy and palaeoenvironmental formation of the rocks in question, relevant perhaps to those with more than a keen interest in the Palaeozoic. It is also a more succinct and contemporary account than the tired and dated Geologists’ Association guide to the Wall.
An examination of the entire wall as a building project and a physical asset, including logistics, and the infrastructure of its construction and maintenance are set out clearly in Ch. 3, ‘The use of stone along Hadrian’s Wall’. It explores aspects of surveying (geological survey), the workforce (the army and interestingly the classis Britannica and slave labour), the building materials (standard terminology) and different building styles, lavishly illustrated with line drawings and photographs of the fort at Birdoswald. Facing-block sizes recorded in vast quantity during the project provide the raw data for a schema of dressed stone, particularly along the curtain wall. It also explores the reuse of ceramics and spolia (e.g. tombstones) as a means of dating later repairs to the wall.
Ch. 4 focuses on evidence for the Roman quarries themselves, using a rating system based not only on tried and tested criteria such as epigraphic and iconographic evidence but, refreshingly, the application of new fieldwork methods involving chisel marks, wedge holes, cut stone, spoil heaps and quarry roads. Probable and certain categories of Roman quarry now amount to at least 21, a considerable advancement on existing studies. Thin section photomicrographs clearly illustrate similarities in the types of sandstone used at Roman quarry and fort, as shown by the Queen’s Crag quarry and Housesteads Roman Fort. A gazetteer at the end of the monograph catalogues all the accessible quarries, encouraging the reader to visit and explore these (public) quarries.
Exploring the vast quantity of stone recycled from the wall and forts to furnish medieval abbeys and post-medieval farms in the wall corridor is the focus of Ch. 5. Although the migration of large quantities of inscribed and sculptural stone had already been well attested, this study expands the number substantially, showing the reuse of quoins and even rubble core into medieval defensive (Thirlwall Castle) and ecclesiastical buildings (Lanercost Priory).
Much of the vast body of data accrued during the WallCAP project through the diligent work of volunteers, local communities and professionals alike and collected through two strands of empirical study, the Heritage at Risk (HAR) and Stone Sourcing and Dispersal (SSD), is not included here. But sister publications and online datasets Archaeological Data Service (ADS) and Newcastle University (Ncl) provide the completist with a comprehensive body of geological and architectural data.
The successful application of an empirical earth science approach to understanding the character and source of the stone materials in this, one of the most iconic and world-renowned stone construction projects in the Roman world, continues the pioneering work undertaken at the University of Reading by geologists Bruce Sellwood and John Allen on the defensive wall circuits at Silchester and Caerwent. It follows that the methodology/results garnered here can be applied to other major defensive structures in the province such as the wall at Colchester. Indeed, the geological data/results gathered from this study will help to re-evaluate the geological source and character of the Roman inscriptions from Hadrian’s Wall as well as the sculptural stone catalogued in the two volumes of the CSIR corpus of Roman Sculpture which use such broad-brush terms such as sandstone or limestone.
