By Salma El-Sakka
A new geological study has ruled out the theory that Stonehenge's six-tonne Altar Stone originated in northeast Scotland, deepening the mystery surrounding the monument's central sandstone slab.
Scotland theory eliminated
The 4.9-metre stone, unique among Stonehenge's megaliths, was previously thought to come from Wales before a 2023 study pointed to the Orcadian Basin in Scotland. Researchers led by Professor Duncan Pirrie of the University of South Wales conducted extensive tests in that region but found no matching geological characteristics.
Ongoing search
"Ruling out potential source areas is just as important as identifying new ones," said Professor Nick Pearce of Aberystwyth University, who contributed to the earlier research. He noted that each eliminated location narrows the search for the stone's true origin.
The latest investigation, published in the Journal of the Geological Society, combined new field observations with analysis of stone fragments held in museum collections. It examined the stone's structure, mineralogy, and geochemical composition to build what Pirrie called "the clearest picture yet" of the Altar Stone.
Broader context
Stonehenge was built in phases between 3000 and 1600 BC. While the smaller bluestones were transported around 225 kilometres from west Wales, the Altar Stone's provenance remains unresolved. Determining its source could shed light on the long-distance connections and engineering capabilities of Neolithic Britain.
