Stonehenge’s 6-ton altar stone may have ridden a glacier down from Scotland

A six-tonne sandstone slab embedded in the middle of Stonehenge has been traced to a stretch of northeast Scotland roughly 700 kilometers away, and a new study now asks how a Neolithic community without wheels or draft animals ever moved it there. Researchers at Sheffield Hallam University and Curtin University combined mineral-grain dating with computer models of the last Ice Age’s glaciers to test whether nature alone could explain the journey. It could not: the ice, their modeling shows, ran out hundreds of kilometers short of Salisbury Plain.

Dr Anthony Clarke of Curtin University and Dr Remy Veness of Sheffield Hallam co-led the analysis, working alongside colleagues from the University of Sheffield, Wessex Archaeology, the University of Bristol and Curtin geochronologist Chris Kirkland. Their paper, titled “From Highlands to Henge,” appears in the Journal of Quaternary Science and updates a debate that has run since the Altar Stone’s Welsh origin theory was first overturned.

A six-tonne remnant traced past Wales, into Scotland

Stonehenge’s other large sarsen stones come from West Woods, roughly 25 kilometers from the monument, so for decades many archaeologists assumed the Altar Stone shared a similarly local, Welsh origin. That assumption collapsed once earlier mineral analysis traced the Altar Stone roughly 700 kilometers north, to the Orcadian Basin in northeast Scotland, a result the new study treats as settled ground and uses as the starting point for its transport modeling, reported this week by ScienceDaily’s coverage of the Sheffield Hallam and Curtin findings.

That earlier origin study left an open question the new paper set out to answer: if the stone came from that far north, did it travel by ice, by human effort, or some combination of both. Six tonnes is well within the range glaciers are known to move, which kept the natural-transport theory alive even after Scotland replaced Wales as the accepted source.

Ice sheets can carry a boulder only so far

The team’s ice-sheet models allowed for glacial transport partway, showing the Altar Stone could plausibly have ridden ice as far as Dogger Bank, a shallow rise in the North Sea that was dry land during the last Ice Age. Beyond that point, according to the modeling described in a EurekAlert release detailing the study’s methods, there was no realistic glacial route running south into England; every simulated ice sheet stalled or diverted before reaching Salisbury Plain.

Dr Clarke summed up what that gap in the ice record leaves standing. “Rather than being carried naturally by ice, the evidence points to a deliberate, carefully planned movement across a challenging and varied landscape,” Clarke said, describing a route that required “planning, coordination and a deep understanding of the landscape” for the remaining hundreds of kilometers.

Doggerland’s stone and a staged human haul

If people picked up the transport where the ice left off, they would have started from a coastline now submerged. Dr Veness pointed to what that implies about the communities living on Doggerland, the land bridge that once connected Britain to continental Europe before rising seas swallowed it. “What is exciting about these findings is that they could imply that people of Doggerland attached cultural significance to the Altar Stone long before it was incorporated into Stonehenge,” Veness told Sheffield Hallam University, framing the stone’s move as a value judgment made well before it reached the monument.

The likeliest overland route runs partly along the Berkshire Ridgeway, a prehistoric track sometimes described as Europe’s oldest road, mixed with stretches of river or coastal transport where the terrain allowed it. Moving six tonnes that way, in stages, across hundreds of kilometers of unmapped Neolithic Britain would have taken sustained cooperation among people who left no written account of the effort, and no wheel, cart or draft animal to lighten it.

Sledges dragged over log rollers, rafts poled along river stretches, and long overland hauls guided by landmarks that no longer exist are the working assumptions behind that route, pieced together from how other Neolithic megaliths elsewhere in Britain and continental Europe are believed to have moved. None of those methods leaves the kind of physical trace a glacier does, which is part of why the human-transport half of the journey has proven harder to pin down than the geological half.

Rewriting the last unsolved leg of Stonehenge’s supply chain

Every other stone at Stonehenge already has a settled transport story: the sarsens from West Woods likely moved on sledges and rollers over a short distance, and the smaller bluestones from Wales are widely accepted as a human haul across roughly 225 kilometers. The Altar Stone was the outlier, the one piece whose distance seemed to argue for a shortcut nature might have provided.

With that shortcut ruled out by the modeling, the Altar Stone becomes the monument’s longest confirmed transport job by a wide margin, one that started on a coastline that no longer exists. A Curtin University summary of the research framed the finding as evidence that Neolithic communities carried the organizational skill, landscape knowledge and coordination needed to move a boulder that size across hundreds of kilometers of unmapped territory, without draft animals or the wheel.

What remains unanswered is the exact path those haulers took across the intervening centuries between leaving the Orcadian coast and arriving at Salisbury Plain. Clarke’s team says the gap is now a fieldwork question rather than a modeling one, since the glacial half of the journey is settled and only the human half still needs tracing on the ground.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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