Brighton scientists unlocking the secrets of Stonehenge

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 focusses 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: “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.

Dr Jake Ciborowski working on a sarsen

Stonehenge (c) English Heritage credit Andre Pattenden

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).”

“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. 

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.