GeoArch undertakes projects involving the investigation of geological materials for archaeological purposes. These materials include lithic and ceramic of both natural and artificial origin. This is geoarchaeology in the broad sense. The materials with which GeoArch is most closely involved are iron ores. However, the iron ores are not only significant within metallurgical contexts; the following case studies, selected from recent projects, illustrate the possibilities ore provenance studies:
The Bristol Channel Orefield provenancing studies also include analysis of the cargo of the 13th century vessel from Magor Pill, now interpreted to be carrying ore from the Vale of Glamorgan.
This backscattered electron image (field of view 500µm wide) shows quartz crystals (dull) intimately associated with goethite (bright). The presence of quartz is one of the key pieces of evidence indicating that the cargo did not originate in the forest of Dean as had been supposed initially. Other lines of evidence used to support a Glamorgan origin for the cargo include details of the trace element geochemistry including the rare earth element (REE) distribution, the level of uranium, the levels of the trace elements lead, zinc and barium, as well as details of the physical properties of the ore, including the angle between internal layering and stalactitic ores.
Without the detailed analysis the origin of the ore was likely to have been attributed to the Forest of Dean, the main regional source of goethite ores. Such an attribution would have had big implications for subsequent interpretations of trade patterns.
REDKNAP, M. & YOUNG, T.P 1998. The iron industry of south-east Wales in the 13th century. pp. 112-115 In: Nayling, N. The Magor Pill Medieval Wreck, CBA Research Report 115, Council for British Archaeology. [ISSN 0141 7819, ISBN 1 872414 86 9]
YOUNG, T.P. & THOMAS, G.R. 1998. The cargo: iron ore analysis. pp. 105-111 In: Nayling, N. The Magor Pill Medieval Wreck, CBA Research Report 115, Council for British Archaeology. [ISSN 0141 7819, ISBN 1 872414 86 9]
YOUNG, T.P. & THOMAS G.R. 1999. Provenancing iron ore from the Bristol Channel Orefield: the cargo of the Magor Pill Boat. In: POLLARD, A.M. (ed) Geoarchaeology: exploration, environments, resources, Geological Society of London, Special Publication, 165, 103-121.
The famous "Red Lady" from Paviland, on Gower, South Wales, is a male burial from c. 26,000 b.p. In common with other Gravettian ceremonial burials, the body was placed in, or coated with, ochre. Several lumps of iron ore are also present in the collections from the early excavations at the site. This materials were re-examined with a view to establishing the provenance of the iron ores and determining whether the nature of ochre coating could be determined.
The petrography of the ores included micro-botryoidal textures, sometimes associated with small arborescent growths, with a mineralogy dominated by haematite flakes (image to right). Such textures can be closely paralleled in samples from veins in Langland Bay and at Mumbles, in eastern Gower. The trace element geochemistry of the ores was characterised by elevated levels of As, Ge, V and Pb, associated with very low levels of Ti. Two samples from Paviland had a high U content also, and were extremely close in composition to samples taken from a vein in Langland Bay.
Chemical analysis of the ochre demonstrated that this material was compatible in composition with a mixture of material similar to local boulder clay with crushed iron ore of the same composition as the analysed lumps from the site.
The identification of the iron ore veins which cut eastern Gower as the source of the haematite employed in the Palaeolithic rituals at Paviland may be significant for these veins may have formed highly visible landscape features at periods of reduced vegetation. Even today, where the veins have not been quarried on the foreshore they are still impressive.
YOUNG, T.P. 2000. Chapter 10. The Paviland Ochres: characterisation and sourcing. In: ALDHOUSE-GREEN, S., Paviland Cave and the 'Red Lady': a definitive report. Western Academic and Specialist Press Limited, 205-225. [ISBN: 0-9535418-1-9]