A pivotal 6-ton sandstone megalith, identified as the Altar Stone and situated at the heart of Stonehenge’s celebrated arrangement, originated from a source at least 750 kilometers away from its present-day position, according to recent investigations spearheaded by archaeologists from Curtin University.
Stonehenge. Image credit: Regina Wolfs.
The prehistoric standing stone circle known as Stonehenge, located in Wiltshire, England, on the Salisbury Plain, provides profound insights into the culture and practices of Neolithic Britain.
The commencement of construction at Stonehenge dates back to approximately 3000 BCE, with subsequent enhancements and alterations carried out over the subsequent two millennia.
The formidable stone structures that comprise Stonehenge are broadly categorized into two distinct types: sarsen stones and bluestones.
The more substantial sarsen stones are primarily composed of duricrust silcrete, with their geological provenance predominantly traced to West Woods, near Marlborough, situated roughly 25 kilometers north of Stonehenge.
Bluestone, a collective designation for geological materials considered foreign to the immediate vicinage, encompasses various rock types including volcanic tuff, rhyolite, dolerite, and sandstone.
The central monolith of Stonehenge, referred to as the Altar Stone, stands as the largest among the bluestones. It measures 4.9 meters by 1 meter by 0.5 meters and is a horizontally positioned rock, tipping the scales at 6 tons. Its composition is a pale green micaceous sandstone characterized by a unique mineralogical signature.
In a recently concluded research endeavor, Anthony Clarke, a doctoral candidate at Curtin University, alongside his academic colleagues, meticulously examined the age and chemical makeup of mineral grains found within fragments of the Altar Stone.
“Our analysis concerning the age and chemical signature of the minerals embedded within fragments of the Altar Stone established a correlation with rocks from northeastern Scotland, while simultaneously clearly distinguishing them from geological formations in Wales,” stated Clarke.
“We identified specific mineral grains within the Altar Stone whose ages predominantly range from 1 to 2 billion years, with other minerals dating back approximately 450 million years.”
“This data furnishes a distinctive chemical marker, strongly suggesting that the stone originated from rock formations within the Orcadian Basin in Scotland, a location situated at least 750 kilometers from Stonehenge.”
“Considering its Scottish origins, these revelations give rise to intriguing inquiries, particularly regarding the technological capabilities of the Neolithic era and the methods employed to transport such a colossal stone across considerable distances around 2600 BCE.”
The layout of Stonehenge and the appearance of the Altar Stone. Image credit: Clarke et al., doi: 10.1038/s41586-024-07652-1.
“These findings possess considerable implications for our comprehension of ancient societies, their interconnections, and their methods of long-distance transportation,” remarked Professor Chris Kirkland of Curtin University.
“Our identification of the Altar Stone’s provenance underscores a remarkable degree of societal organization during the Neolithic period and contributes to a vivid depiction of prehistoric Britain.”
“The logistics of conveying such massive cargo overland from Scotland to the southern regions of England would have presented immense difficulties, strongly indicating the probable utilization of a maritime shipping route along the British coastline.”
“This suggests the existence of extensive trade networks and a more sophisticated level of societal structure than is generally attributed to the Neolithic period in Britain.”
“We have successfully ascertained, if one might put it that way, the geological age and chemical composition of what is arguably one of the most renowned stones within a globally celebrated ancient monument,” stated Professor Richard Bevins from Aberystwyth University.
“While we can now definitively assert that this iconic rock is of Scottish rather than Welsh origin, the pursuit to pinpoint its exact origin within northeastern Scotland remains an active area of investigation.”
“The results were truly astonishing, but assuming the accuracy of principles in plate tectonics and atomic physics, then the Altar Stone is indeed Scottish,” commented Dr. Robert Ixer from University College London.
“This research raises two pivotal questions: what was the motivation, and by what precise means was the Altar Stone transported from the northernmost reaches of Scotland, covering a distance exceeding 70 kilometers, to Stonehenge?”
The research findings have been formally published in the esteemed scientific journal Nature.
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A.J.I. Clarke et al. 2024. A Scottish provenance for the Altar Stone of Stonehenge. Nature 632, 570-575; doi: 10.1038/s41586-024-07652-1
