THE BOOK
Some of the ideas discussed in this blog are published in my book called "The Bluestone Enigma" -- available by post and through good bookshops everywhere. Bad bookshops might not have it....
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Sunday, 25 October 2015

Lecture on the Stonehenge Bluestones

Happy to give a puff for this one -- a lecture by Richard Bevins at the Wilts Museum in Devizes.  Thanks to Tony for the alert.....

LECTURE: Old Stones, New ideas: Sourcing the Stonehenge Bluestones

2:30 pm, Saturday, 21 November, 2015
Wiltshire Museum, Devizes

A Saturday afternoon lecture by Richard Bevins.
Stonehenge is arguably one of the most famous prehistoric monuments in the World. It is renowned for the enormous size of the sarsen monoliths used in its construction which comprise the Outer Circle and Outer Horseshoe. It is generally agreed that these stones were sourced from the Marlborough Downs area, some 30 km to the north of Stonehenge. However, a set of smaller stones, comprising the Inner Circle, the Inner Horseshoe and the Altar Stone, are exotic to the Salisbury Plain area; these are the so-called bluestones, and have been the subject of investigations since the latter part of the 19th Century. Early petrographical studies recognised that the bluestones largely comprise a range of altered volcanic, intrusive and tuffaceous rocks with rarer sandstones but could not provide a definitive source.

However, it was the seminal paper by H.H. Thomas in 1923 that persuasively demonstrated that the spotted dolerite component of the bluestones could be sourced to outcrops exposed towards the eastern margin of Mynydd Preseli in southwest Wales, citing the tors Carn Meini and Cerrigmarchogion as the most likely sources. Thomas also argued that other lithologies in the bluestone assemblage, notably the rhyolites and the ‘calcareous ash’, could be sourced in the same locale, in particuar from Carn Alw and the northern slopes of Foel Drygarn respectively.

The first major investigation of the geochemistry of bluestone assemblage was by Richard Thorpe and team who compared whole rock wavelength-dispersive X-ray fluorescence spectrometry analyses from both orthostats and debitage at Stonehenge with whole rock analyses from Mynydd Preseli
.
Using petrography, mineral chemistry and whole rock geochemistry Richard Bevins and Rob Ixer have re-examined the proposed source of the bluestone rhyolites and determined that Carn Alw, as proposed by Thomas, is not the source of bluestone rhyolite; instead they argued that the majority of the rhyolite debitage from the Stonehenge Landscape (but not the four rhyolitic/dacitic standing or recumbent orthostats) comes instead from a prominent outcrop called Craig Rhos y felin, located on low ground to the north of the Mynydd Preseli range in the vicinity of Brynberian. More recently they have re-examined the spotted and non-spotted dolerites and concluded that a large % of the dolerite fragments and cored samples from Stonehenge come from Carn Goedog rather than Carn Meini.


Biography
Dr Richard Bevins as Keeper and Head of the Department of Natural Sciences at the National Museum Wales in Cardiff is responsible for Strategic leadership for collections and research related activities within the Department.

Qualifications, memberships and relevant positions:
BSc (Hons) Geology (Aberystwyth University), PhD (Keele), Fellow (Geological Society of London), Chartered Geologist (CGeol), Fellow (Society of Antiquaries of London), Honorary Lecturer (School of Earth & Ocean Sciences, Cardiff University), Chair, Geological Society of London’s Geoconservation Committee, Member of the Geological Society of London’s External Relations Committee, Chair of the British Geological Survey’s National Geological Repository Advisory Committee.

References
Primary research area is centred on the the Caledonian igneous history of Wales and related areas, as well as on their low-grade metamorphism. More recent work has focussed on extending the petrology and geochemistry of altered igneous rocks from Pembrokeshire into a re-examination of the source of the Stonehenge bluestones.

Selected Publications:
Bevins, R.E., Ixer, R. A. & Pearce, N.J.G. 2014. Carn Goedog is the likely major source of Stonehenge doleritic bluestones:evidence based on compatible element geochemistry and Principal Component Analysis. Journal of Archaeological Science, 42, 179-193.

Ixer, R.A. & Bevins, R.E. 2014. Chips off the old block: the Stonehenge debitage dilemma. Archaeology in Wales, 52, 11-22.

Bevins, R.E., & Ixer, R. A. 2013. Carn Alw as a source of the rhyolitic component of the Stonehenge bluestones: a critical re-appraisal of the petrographical account of H.H. Thomas. Journal of Archaeological Science, 40, 3293-3301.

Bevins, R.E., Ixer, R. A., Webb, P.C. & Watson, J.S. 2012. Provenancing the rhyolitic and dacitic components of the Stonehenge landscape bluestone lithology: new petrographical and geochemical evidence. Journal of Archaeological Science, 39, 1005-1019.

Parker Pearson, M., Pollard, J., Richards, C., Thomas, J., Welham, K., Bevins, R.E., Ixer, R., Marshall, P. & Chamberlain, A. 2011. Stonehenge: controversies of the bluestones. In L. García Sanjuán, C. Scarre and D.W. Wheatley (eds) Exploring Time and Matter in Prehistoric Monuments: absolute chronology and rare rocks in European megaliths. Proceedings of the 2nd European Megalithic Studies Group Meeting (Seville, Spain, November 2008). Menga: Journal of Andalusian Prehistory, Monograph no. 1. Seville: Junta de Andalucía. 219-50.

Bevins, R.E., Pearce, N.J.G. & Ixer, R. A. 2011. Stonehenge rhyolitic bluestone sources and the application of zircon chemistry as a new tool for provenancing rhyolitic lithics. Journal of Archaeological Science, 38, 605-622.

Links:
www.researchgate.net/profile/Richard_Bevins2

Saturday afternoon lectures start at 2.30pm and last approx. one hour.

Our Lecture Hall is accessible via a lift if required, has a hearing loop and air conditioning.

Booking:

Essential.

Booking Options
Book online using Paypal
Telephone – 01380 727369
Email – hello@wiltshiremuseum.org.uk
Visit – Wiltshire Museum, 41 Long Street, Devizes

1 comment:

chris johnson said...

So refreshing to read someone writing with such clarity. I would like to go to the lecture but cannot, so hope one of my "friends" on this blog will be able to give a report.