The mystery of Stonehenge and its enigmatic Altar Stone has deepened, according to findings that raise new questions about the massive slab’s origins and challenge previous research.
According to an international team of researchers investigating the feature’s mysterious provenance, several previously suggested locations for the Altar Stone’s origins have now been ruled out, meaning that archaeologists could be closer to finally resolving where the six-ton stone came from thousands of years ago.
The findings, which appeared in the Journal of the Geological Society, offer the most complete geological analysis yet undertaken of the 16-foot-long stone, which rests near the center of England’s famous Neolithic monument, which has long stood on the country’s Salisbury Plain.
Ancient Journey of the Altar Stone
Researchers have long believed the enigmatic Altar Stone was likely brought to Stonehenge from Wales, since its stone composition is unlike any local stone found in the immediate area.
However, geological evidence from recent past studies suggested that this may not be the case, and that the true origins of the huge slab of stone could be much farther away in northeast Scotland.
If correct, this would raise several questions, including why Neolithic Britons would have carried a six-ton slab of rock across a distance spanning hundreds of miles, and how this might have been achieved.
Geological Clues
Now, in recent work led by University of South Wales emeritus professor Duncan Pirrie, researchers focused on what geological clues the stone might offer about its origins.
Examining the Altar Stone’s mineral composition, chemical characteristics, and isotopic signatures, Pirrie and his colleagues compared these with geological samples from a variety of proposed source locations from Scotland’s Orcadian Basin. However, based on the team’s analysis, none of the tests produced an exact match with any of these samples, meaning that the search for the origins of the Altar Stone remains open.
While the longstanding debate over the stone’s origins will continue, Pirrie and his team say that their findings nonetheless offer a more detailed geological “fingerprint” of the stone’s composition, which could significantly aid researchers in narrowing the possible origins in future investigations.
“In a geological detective story such as this, ruling out potential source areas is just as important as identifying new ones,” said Aberystwyth University emeritus professor Nick Pearce, who was involved with the recent research.
The Path Toward Solving the Mystery
Going forward, the research team says they hope their discoveries could ultimately reveal the true origins of the Altar Stone, which could also help determine what kinds of transportation methods would have been used to bring it to Wiltshire, offering deeper insights into the engineering capabilities of the ancient Britons who constructed one of the country’s greatest neolithic marvels.
The team published their research in the recent paper, “Searching for the origin of the Stonehenge Altar Stone: new sedimentological, petrographical, mineralogical, geochemical and isotopic constraints,” which appeared in The Journal of the Geological Society.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.