Stonehenge

Stonehenge, The Prehistoric Megalithic Structure on Salisbury Plain. (Photo by Sonia Bonet on Shutterstock)

For over a century, the question of how the famous bluestones of Stonehenge made their way from their source in Wales to the ancient monument in England has been a topic of heated debate. The bluestones are the smaller boulders that form the site’s inner circle and inner horseshoe. Most archaeologists have long believed that Neolithic people transported these massive stones, each weighing several tons, over 200 kilometers to the site. But a recently rediscovered boulder found during excavations at Stonehenge in 1924 may finally provide the key to solving this age-old mystery.

Geomorphologist Brian John argues that this small, unassuming stone, known as the Newall Boulder, shows clear signs of having been transported and shaped by glaciers. This suggests that ice, not humans, may have been responsible for moving Stonehenge’s giant megaliths. “The simplest explanation of the presence of the bluestones at Stonehenge is that they are glacial erratics from the west, emplaced by ice at some site still to be discovered, on or near Salisbury Plain, where they were later collected up and used by the builders of the stone monument,” John writes in his paper, published in the open-access E&G Quarternary Science Journal.

Methodology: Newall Boulder analysis

To unravel the Newall Boulder’s complex history at Stonehenge, John subjected it to detailed visual analysis, carefully examining its shape, facets, and surface features. The boulder, measuring about 22 x 15 x 10 cm, has a distinctive bullet-like shape with a pointed end and a blunt end. It sports at least five major facets and several smaller ones, with abraded surfaces and edges. Intriguingly, there are also fracture scars, faint scratches, and what appear to be crescentic gouges — all potential indicators of glacial transport and erosion.

John also examined evidence of human modification, including apparent percussion scars from when someone in prehistoric times seemed to have unsuccessfully tried to shape the boulder into a tool such as an axe. More recent damage from geological sampling was also evident. To establish the boulder’s provenance, John compared its petrology and geochemistry to potential source rocks in Wales, though a precise origin remains elusive.

A much-discussed photograph of the Newall Boulder
A much-discussed photograph of the Newall Boulder, annotated by the author. The shape and surface features are widely interpreted as indicators of sub-glacial transport, in spite of heavy damage by humans. (Credit: The Institute of Geological Sciences/British Geological Survey)

Results

The cumulative evidence from the Newall Boulder’s shape and surface features makes a compelling case for glacial transport to Stonehenge. Its bullet-like morphology with a distinct “stoss” (upstream) and “lee” (downstream) end is classic for clasts that have been subglacially dragged, rolled and lodged in flowing ice. The facets, striations, and chatter marks are also highly consistent with the boulder having been scraped and crushed at the base of a glacier.

Curiously, the boulder has a weathering rind up to 5 millimeters thick on its upper surface, but fresh, unweathered facets on its flanks and underside. This suggests it once lay partially buried for an extended period, with its top exposed to the elements. Subsequent human modification left percussion scars on this weathered surface, hinting that Stonehenge’s builders found the boulder as a loose, pre-weathered erratic at the site – not as freshly quarried stone.

Six of the Stonehenge bluestones belonging to the bluestone circle
Six of the Stonehenge bluestones belonging to the bluestone circle, in the NE quadrant of the stone monument. They are overlooked by the larger sarsens of the outer circle. For scale, stone 47 is 1.45 m tall. For the most part the bluestones are not elegant pillars but heavily abraded and weathered erratic boulders and slabs. (Credit: Brian John)

‘Shortcomings’ Of Human Transport Theory

Despite the prevailing belief that Neolithic people transported the bluestones to Stonehenge, John highlights numerous studies showing why there are numerous problems with this theory. First and foremost, there is no evidence from any other British Neolithic site of megaliths being moved such vast distances. In fact, the builders of other monuments consistently used whatever large stones were locally available. If Stonehenge’s stones were specifically selected and brought from Wales, it’s odd that they come from at least 30 different rock sources — a geological diversity more consistent with the random “sampling” of glacial action than deliberate human choice.

The sheer variety of stone types at Stonehenge also argues against the idea of a special connection to Wales or the “sacredness” of the bluestones, as does the lack of any evidence that these particular rocks were prized or venerated in their homeland. If acquiring the bluestones was a major driver of Stonehenge’s construction, it’s puzzling that no Neolithic quarries, stone-moving equipment, or infrastructure have been found. Experimental archaeology has also highlighted the immense practical challenges of transporting multi-ton monoliths across the boggy, densely forested Neolithic landscape using only Stone Age technology.

Perhaps most damningly, there is no evidence of the kind of sophisticated stone-moving culture that should have existed if Neolithic Britons had undertaken such a massive feat of megalith transport. The skill, planning, and organization needed to move Stonehenge’s monoliths is curiously absent from the archaeological record before and after the monument’s construction. If the builders had such advanced capabilities, why did they not use them at other sites or pass them down to their descendants? The lack of any corroborating evidence for large-scale human stone transport suggests that this theory, while entrenched, rests on shaky foundations.

Discussion & Takeaways: Stonehenge bluestones a ‘gift’ from Mother Nature?

The implications of the Newall Boulder’s glacial origins are profound. If this diminutive “reject” found in the monument’s debitage is an ice-rafted erratic, then it’s probable that Stonehenge’s giant standing stones — many of which are also faceted, abraded boulders geologically out of place on Salisbury Plain — were likewise delivered by glaciers. Rather than being purposefully selected and heroically transported by Neolithic builders, they may simply have been fortuitously lying around the site, gifts left behind by ice age glaciers.

This “glacial theory” elegantly explains many puzzling aspects of Stonehenge’s megaliths, from their sheer diversity of rock types to the lack of any evidence for stone-moving infrastructure. It suggests that the monument’s location may have been chosen precisely because of the convenient scattering of giant boulders, not the other way around. And it would overturn the orthodox archaeological narrative of long-distance human transport in favor of a simpler story of our ancestors opportunistically making use of an “erratic quarry” created by nature.

Whether the bluestones were moved by human hands or by the irresistible momentum of glaciers, Stonehenge remains a testament to the ingenuity, adaptability, and sheer ambition of our Neolithic ancestors – and a source of enduring wonder for us today.

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