Stonehenge altar origin remains mystery after Scotland theory ruled out

A dedicated group of geologists recently endured harsh weather on Scottish hillsides to trace the source of one of Stonehenge’s most mysterious components. Despite their efforts, a new scientific report indicates that the origin of the altar stone remains a mystery, and researchers may have been investigating the incorrect region entirely.

One expert referred to the stone's history as an “enigma,” while another called the research a geological detective story that lacks a clear conclusion. The investigation gained momentum in 2024 when specialists from universities in Australia, Wales, and London analysed sandstone grains and proposed the stone originated in north-east Scotland, a location over 400 miles away from the monument.

A team member described this initial finding as “jaw-dropping,” prompting widespread speculation regarding how the six-tonne slab was transported, whether by ship or sledge, and what it suggested about neolithic transport networks. Further experts from Sweden, Italy, Canada, and Scotland joined the project to perform detailed analyses of the slab, including non-invasive site examinations and testing of eight museum-held fragments.

Equipped with this geological profile, the researchers travelled to north-east Scotland to search for a precise match with local outcrops. Nick Pearce, an emeritus professor of geochemistry in the department of geography and earth sciences at Aberystwyth University, described the mission as searching for a needle in a haystack.

“The problem is, it’s a very big area, thousands of square kilometres. The only way to do it is to get out there and find the samples,” he said. “You have to plan carefully. One of my colleagues was there recently and he got caught in the storms, which isn’t ideal field weather for geology. We’ve taken about 70 samples, brought them back to laboratories and tested them.”

Laboratory results suggest it is unlikely that the altar stone originated from north-east Scotland. Pearce noted that he was not discouraged by the lack of a definitive result, stating: “We’re getting closer. In a geological detective story such as this, ruling out potential source areas is just as important as identifying new ones. Every location eliminated narrows the search and brings us closer to discovering where the altar stone originated. I’m not disappointed. It’s part of the process.”

Duncan Pirrie, an emeritus professor at the University of South Wales who led the study, concluded that it was “very unlikely” the stone came from north-east Scotland. He further stated that the slab definitely did not originate in southern Britain, suggesting it might have come from other parts of Scotland, northern England, or perhaps Ireland.

Pirrie described the stone’s origins as an enigma but added: “This is the most comprehensive geological investigation of the altar stone ever undertaken. By combining a wide range of analytical techniques, we have built the clearest picture yet of the stone’s composition and tested the leading theories about its origins. So far, none of the locations examined have the same set of characteristics as the altar stone, but the search is not over.”

Stonehenge expert Mike Pitts, who was not involved in the research, noted that identifying the origin of the altar stone remains an exciting prospect. “Doing so would greatly help fit the altar stone into the world of the people who moved it. We’d get to see the landscape through their eyes. To know exactly where the journey began.”