The Stonehenge sarsens -- from "more than one location"

Prof David Nash of University of Brighton -- lead researcher in this project

We have seen some signs that the new research on the provenencing of the sarsens is nearing publication. We reported on the research back in 2018:

https://brian-mountainman.blogspot.com/2018/09/some-stonehenge-sarsens-came-from-kent.html 

In 2019 (see below) there was a press report that suggested that there may be multiple sources for the Stonehenge sarsens.    Now two seminars are being publicised for the month of May, so it looks as if publication of the results is imminent.....  Watch this space.

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Stonehenge mysteries are now being solved
By Arron Hendy
7 May 2019

https://www.theargus.co.uk/news/17624845.stonehenge-mysteries-are-now-being-solved/

BOFFINS from the University of Brighton are helping to solve the mystery of where the ancient stones at Stonehenge originate.

Different theories have been debated by archaeologists and geologists for more than 100 years and now English Heritage, which manages the prehistoric site in Wiltshire, is hoping chemical analysis and comparisons by the Brighton scientists will unlock the puzzle.

The origins of the smaller “bluestones” at the centre of the monument have been traced to Pembrokeshire in west Wales. This latest research focuses on the large sarsen stones that make up the main stone circle and inner sarsen horseshoe.

In 2018, the Brighton team analysed the chemistry of the sarsen uprights at the monument. This latest research involved chemical analysis of the sarsen lintel stones that sit across the top of these uprights. The “non-invasive” procedure used a portable spectrometer that can identify chemical concentrations of a range of elements.

Professor David Nash, the University of Brighton’s Professor of Physical Geography, said: “Initial results from our analysis suggest that in fact the sarsens may come from more than one location. Our geochemical fingerprinting of the sarsens in situ at Stonehenge when compared with samples from areas across southern England will hopefully tell us more precisely where the different stones came from.”

He added: “We have now analysed the chemistry of all the sarsen stones and will be comparing the data against the chemistry of areas of sarsens from across southern England.

“The comparisons will be conducted at the University of Brighton, which holds an extensive collection of sarsen samples. This will provide new data about the stones’ source and about the monument itself.”

Professor Nash, Deputy Head (Research and Enterprise) in the University’s School of Environment and Technology (SET), has authored more than 100 publications focusing mainly on geochemical sediments and environmental change.

The Stonehenge ring of stones, described by English Heritage as a “masterpiece of engineering” comprises two stone types: The larger sarsen stones, which are found naturally across southern England, and the bluestones.

Professor Nash said: “Archaeologists and geologists have been debating where the stones used to build Stonehenge came from for years.

“The smaller bluestones have attracted most attention but, in comparison, virtually no work has been done on the sources of the larger sarsen stones.” used to construct the central Trilithon Horseshoe, outer Circle and peripheral settings.

“Conventional wisdom suggests that they all came from the relatively nearby Marlborough Downs, some 20 miles away, where great quantities of sarsens still lie across the landscape, but their exact origin is not known. On average the sarsens at Stonehenge weigh 25 tons, with the largest stone, the Heel Stone, weighing about 30 tons.

“The most accurate means of determining the provenance of any stone artefact is geochemical fingerprinting, whereby the elemental chemistry of the artefact is matched against that of potential source areas. For Stonehenge, this would require two stages: an initial analysis of the sarsen stones at the monument, followed by equivalent analyses of sarsen boulders across their range of natural occurrence (south of a line from Devon to Suffolk).”

Professor Nash and colleague Dr Jake Ciborowski, Senior Lecturer in SET, have been undertaking the study as part of a project funded by the British Academy and the grant-making foundation the Leverhulme Trust. Partners in the project include the archaeologists and Stonehenge experts Professor Timothy Darvill (Bournemouth University) and Professor Mike Parker Pearson (University College London).

Previous research, using laser scanning data, has suggested there are sarsen stones with differing chemistries and hence potentially different sources at the monument. The new chemical analysis and comparisons are expected for the first time to provide more definitive conclusions.
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Upcoming seminar:

Physical Geography Seminars: 'Geochemical Fingerprinting the Sarsen Stones at Stonehenge'
7th May 2020, 14:00 to 15:30, W007, Main Geography Building, Professor David Nash, University of Brighton

…. and also at Wiltshire Museum on 30 May 2020…….

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https://research.brighton.ac.uk/en/projects/geochemical-fingerprinting-the-sarsen-stones-at-stonehenge

University of Brighton research project (now finished — publications awaited…….)

Geochemical fingerprinting the sarsen stones at Stonehenge
• Nash, David (PI)
• Ciborowski, Jake (CoI)

Description
Overview
The sources of the stone used to construct Stonehenge have been debated by archaeologists and geologists for over a century. The smaller Bluestones, derived from west Wales, have attracted most attention. In comparison, virtually no work has been done on the sources of the larger sarsen stones (silcretes) used to construct the central Trilithon Horseshoe, outer Circle and peripheral settings. Conventional wisdom suggests that, given their size, the sarsens were all sourced from the Marlborough Downs. However, petrological, mineralogical and laser-scanning analyses indicate considerable variability among the Stonehenge sarsens, making this assumption questionable.

The most accurate means of determining the provenance of any stone artefact is geochemical fingerprinting, whereby the elemental chemistry of the artefact is matched against that of potential source areas. For Stonehenge, this would require two stages:

1. an initial analysis of the sarsen stones at the monument,followed by
2. equivalent analyses of sarsen boulders across their range of natural occurrence (i.e. south of a line from Devon to Suffolk).

Project aims
This project, funded by British Academy/Leverhulme Small Research Grant SG170610, addresses the first of these stages. The primary aim is to determine, for the first time, the chemical variability of the sarsen stones at Stonehenge. This will allow us to assess whether, as appears likely from laser scanning data, there are stones with differing chemistries (and hence potentially different sources) at the monument.
Our second aim is to undertake pilot chemical analyses of sarsen boulders from selected areas of southern England, including clusters close to Stonehenge (e.g. Marlborough Downs) and more distant (e.g. Hants, Sussex, Kent, Suffolk). This will allow us to scope, for the first time, the chemical variability in natural sarsen occurrences, and more efficiently target areas for intensive investigation in the future.

To avoid the need to core at the monument, we plan to analyse samples from two collections of sarsen fragments from Stonehenge. These derive from two sets of excavations in 2008 (led by project partners Tim Darvill and Mike Parker-Pearson) and represent a selection of sarsens from the monument. The first, between the sarsen Circle and Trilithon Horseshoe, uncovered sarsen debris from stone-breaking, possibly used as packing materials. The second, to the north of Stonehenge, revealed extensive working debris from two areas where sarsens were dressed prior to erection.

We will analyse each sarsen fragment in these collections using non-invasive pXRF, to identify broad chemical groupings. Based on this, we will select 100 samples from across these groups for combined ICP-MS and ICP-AES analyses. A similar approach will be used to select 40 samples for pilot analysis from the extensive collection of sarsens from southern England held at the University of Brighton. ICP-MS/AES data will be assessed using standard geochemical provenancing approaches to define any chemical groups within the Stonehenge samples, and provisionally match these groups against source areas. Following these analyses we will select samples for further investigation, including via a novel combination of petrological, cathodoluminescence and Qemscan analyses of polished thin-sections, to crosscheck any potential geochemical match.

Key findings
The project is in progress, with a completion date of March 2019. Key results and links to publications will be added here as the project progresses.
Status Finished
Effective start/end date 1/10/17 → 31/03/19
Funding
British Academy