A recent study analyzing mineral grains from Stonehenge's Altar Stone suggests that this massive component of the prehistoric monument was transported hundreds of miles from its origin in northeast Scotland by humans, rather than solely by glaciers as some theories propose.
The Altar Stone, weighing up to six tonnes, originated approximately 430 miles (700km) from its current location in Wiltshire. While glaciers may have played a role in moving the stone out of Scotland, researchers contend that humans were responsible for transporting it at least 250 miles (400km) across challenging terrain.
"Rather than being carried naturally by ice, the evidence points to a deliberate, carefully planned movement across a challenging and varied landscape," stated Dr. Anthony Clarke, co-lead author from Curtin University. "Our modelling shows glaciers may have transported rocks part of the way during the last Ice Age — potentially as far as Dogger Bank in the North Sea — but not into southern England. This means the stone would still have needed to be moved hundreds of kilometers by people."
For the study, published in the Journal of Quaternary Science, researchers examined mineral grains from the Altar Stone and combined this data with ice sheet modeling. This analysis helped pinpoint the stone's origin and assess the feasibility of glacial transport to Stonehenge.
"The research indicates there were no viable glacial pathways linking the source region directly to Stonehenge, reinforcing the conclusion that human transport was required," Dr. Clarke added. "Instead, this suggests the stone was likely moved in stages, potentially combining overland hauling with river or coastal transport where possible."
One proposed route involves glacial transport from Caithness in northeast Scotland across an ice sheet covering the North Sea to Dogger Bank. From there, Mesolithic people might have recovered the stone before the area flooded around 7,000 years ago. Subsequent transport by boat through waterways and then overland via routes like the Berkshire Ridgeway could have led to its final placement at Stonehenge around 2500 BC.
"Glacial transport to Dogger Bank, bypassing uplands in Scotland and Northern England, could conceivably decrease some of the challenges of transporting the Altar Stone. Nevertheless, human agency would still have been required, which may have included primarily maritime pathways via the southeast coast or overland passage along the Berkshire Ridgeway," the study notes.
Even if the stone reached Dogger Bank, moving it the remaining approximately 250 miles would have required significant organizational capacity and labor mobilization from Neolithic people.
Dr. Clarke emphasized that transporting a stone of this size over such distances would have necessitated advanced planning, coordination, and a thorough understanding of the landscape. "Either scenario therefore implies a society capable not merely of moving stone but also coordinating complex, large-scale acts of monument construction across extensive geographic ranges," he said.
Previous theories have estimated that moving such a heavy stone overland could have required hundreds of men using ropes and rollers, but archaeological evidence for the use of rollers has not been found at the site. The study's findings suggest a level of societal organization and cooperation among Neolithic communities that may have been previously underestimated.
Stonehenge, a prominent prehistoric monument in Britain, was constructed in several stages. The final visible structure, largely completed around 3,500 years ago, includes sarsen stones and bluestones. While the bluestones were sourced from Wales, the origin of the larger sarsen stones and the massive Altar Stone has been a subject of ongoing research and debate.