For more than a century, archaeologists have known that some of the stones at Stonehenge came from Wales and were transported – somehow – about 125 miles ( 200km) to the site of the Neolithic monument on Salisbury Plain.
Now, a “jaw-dropping” study has revealed that one of Stonehenge’s central megaliths is not Welsh at all – it is actually Scottish.
In a discovery described by one of the scientists involved as “genuinely shocking”, new analysis has found that the largest “bluestone” at Stonehenge was dragged or floated to the site from the very north-east corner of Scotland – a distance of at least 466 miles (about 750km).
The astonishing finding that the megalith, which is known as the “altar stone”, was transported by prehistoric people from at least as far as present day Inverness, and potentially from the Orkney islands, “doesn’t just alter what we think about Stonehenge, it alters what we think about the whole of the late Neolithic”, said Rob Ixer, an honorary senior research fellow at University College London (UCL) and one of the experts behind the study, which was published in Nature on Wednesday.
“It completely rewrites the relationships between the Neolithic populations of the whole of the British Isles,” he told the Guardian. “The science is beautiful and it’s remarkable, and it’s going to be discussed for decades to come … It is jaw-dropping.”
The altar stone is not one of Stonehenge’s famous trilithons – the immense, lintel-topped sarsen stones, which originate from a mere 16 miles (25km) away, and which today form its outer circle. Instead, the huge sandstone block, 5 metres long and weighing 6 tonnes, lies flat and semi-buried at the heart of the monument, trapped under two fallen sarsens and barely visible to visitors.
Made of a sedimentary rock called old red sandstone, the altar stone is classed as a non-local bluestone and was long thought to have been brought from somewhere in Wales, just as a separate group of Stonehenge’s bluestones are now known to have been quarried in the Preseli Hills in Pembrokeshire.
The altar stone was an outlier, however, and research in recent years led archaeologists, including Ixer, to question whether its origins were Welsh at all.
The new study, which involved experts from Curtin University in Perth, Australia; the University of Adelaide; Aberystwyth University; and UCL, aimed to find out more by examining the stone’s chemical composition and the age of minerals within it.
Taken together, these give a characteristic “age fingerprint” to the sandstone, said Nick Pearce, a professor of geography and earth sciences at Aberystwyth who is another of the report’s co-authors.
“With that age fingerprint, you can match it to the same sort of rocks around the UK – and the match for the age fingerprint was a dead ringer for the Orcadian Basin in north-east Scotland,” he said. “It was completely unexpected to us.”
While identifying the exact site will take further work, the experts have narrowed the potential source area to encompass Orkney; a triangle of land around present-day John o’Groats in Caithness; and a narrow coastal strip stretching south as far as the Moray Firth around Inverness and east to present-day Elgin. Small areas of old red sandstone on Shetland are also theoretically possible sources, but were considered unlikely, Ixer said.
The finding may be astonishing, but the science is not controversial, said Pearce. “It’s very, very well-established science. It’s not something that people can look at say: ‘Oh no, that can’t be right.’”
The odds of the stone coming from elsewhere are “fractions of a percent”, he said.
For many, the biggest question will be one not explored in detail in the scientific paper: how on earth did Stonehenge’s builders transport the giant stone from Scotland to Wiltshire?
“Given major overland barriers en route from north-east Scotland to Salisbury Plain, marine transport is one feasible option,” said the lead author, Anthony Clarke, of Curtin University.
But the archaeologist and writer Mike Pitts, who was not involved in the research but whose work on Neolithic monuments includes the book How to Build Stonehenge, said he believed it was more likely the stone was dragged overland than floated by sea.
He said: “If you put a stone on a boat out to sea, not only do you risk losing the stone – but also nobody can see it.” Instead, a land journey, perhaps taking many years, would engage people en route, with the stone “becoming increasingly precious … as it travels south”, he added. Impossible as it may seem today, an overland journey “was easily within the reach of Neolithic technology”.
“[The study] is exciting and it’s so significant,” said Pitts. “It’s long been known that the bluestones come from Wales, but this identifies links with a quite different part of Britain, and significantly more distant from Stonehenge. So it suggests that the site was known not just to people in the south, but over a much wider area – and that opens suggestions for the whole way we think about Neolithic Britain.”
