The iconic monument of Stonehenge, constructed from stones weighing between 2 and 25 tonnes, continues to baffle researchers regarding how its heavy materials traversed great distances to reach southern England’s Salisbury Plain, as detailed by Gizmodo. While the structure’s stones are not from local bedrock, attention has focused heavily on the Altar Stone, the largest and heaviest of the bluestones. Measuring 4 metres long and weighing 6 tonnes, chemical analysis previously determined that the Altar Stone originated 700 kilometres away in north-east Scotland, specifically from a region of bedrock geology known as the Orcadian Basin.
Debating the Journey of Stonehenge’s Altar Stone
How the sandstone monolith crossed the roughly 435 miles to Salisbury Plain has sparked scholarly debate. According to research published in the uk.news.yahoo.com titled From Highlands To Henge: Refining The Provenance And Transport Pathways Of Stonehenge’s Altar Stone, one possibility is that a glacier carried the rock part of the way southward during the last Ice Age before prehistoric humans completed the journey.
Glacial Modeling Versus Human Transport
Researchers at Sheffield Hallam University and Curtin University used numerical modeling to test whether ice flows could account for part of the route. The study indicates that glaciers may have transported rocks as far as Dogger Bank—a regional topographic high point and glacial moraine off the east coast of England that was once part of Doggerland, a land bridge connecting Britain to mainland Europe.
Dr. Remy Veness, co-lead author of the paper from uk.news.yahoo.com, noted that the findings suggest people in Doggerland may have attached cultural significance to the Altar Stone before it reached Stonehenge. As rising sea levels at the end of the last Ice Age inundated Doggerland around 8,000 years ago, changing climates may have prompted an audacious decision to move the stone onto mainland Britain.
Co-author Dr. Anthony Clarke from heraldscotland.com stated that the modelling shows glaciers did not reach into southern England. The research indicates there were no viable glacial pathways linking the source region directly to Stonehenge, reinforcing the conclusion that human transport was required,
Clarke explained, adding that the stone likely moved in stages combining overland hauling with river or coastal transport.
Scepticism Over the Glacial Hypothesis
Despite the partial-glacier hypothesis, other findings challenge the likelihood of ice involvement entirely. Research published in Communications Earth & Environment examined river sands near Stonehenge for mineral signatures like zircon crystals that glaciers would have eroded and left behind. Finding no such evidence, lead author Anthony Clarke concluded that Salisbury Plain remained unglaciated during the Pleistocene Epoch, rendering direct glacial transport unlikely.
Furthermore, timing discrepancies complicate the ice-flow narrative. Dogger Bank was inundated roughly 8,000 years ago, whereas the construction of Stonehenge did not commence until approximately 5,000 years ago. This timeline requires an increasingly elaborate set of circumstances for glaciation to have moved the block before human intervention.
Neolithic Organisation and Future Research
Whether moved entirely by human labor or assisted initially by glacial drift to Dogger Bank, transporting a six-tonne stone over such distances demanded immense planning, coordination, and cooperation among Neolithic communities. From Dogger Bank, the stone could have been moved close to the Berkshire Ridgeway, the oldest road in Europe.
Future research aims to pinpoint the Altar Stone’s exact source outcrop or quarry in north-east Scotland and further investigate the specific transport routes utilized by prehistoric communities.
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