Altar Stone Mystery Deepens as New Study Rules Out Scotland Origin

A new geological study has ruled out the theory that Stonehenge's Altar Stone came from the Orcadian Basin in north east Scotland, the BBC reported. Researchers tested the area but found no location matching the stone's characteristics, so where the six tonne slab originated remains an open question.

The findings were published in the Journal of the Geological Society. The researchers say that eliminating places still moves the search forward.

What did the new study find?

According to the BBC, scientists carried out tests in the Orcadian Basin area of Scotland and failed to find a place with the same characteristics as the Altar Stone. That rules out a theory that had recently gained ground.

The study was led by Professor Duncan Pirrie of the University of South Wales. He described his latest publication as the most comprehensive geological investigation of the Altar Stone ever undertaken, and said it has built the clearest picture yet of the stone.

What was believed about the stone's origin before?

The Altar Stone is a 4.9 meter sandstone slab within the circle. The BBC said it was first believed to have come from Wales. A more recent study then pointed toward north east Scotland. The new work overturns that second theory without replacing it with a confirmed source.

How was the research carried out?

The BBC reported that the team combined new observations with an examination of fragments of the stone held in museum collections. The researchers looked at the stone's structure, minerals and composition.

What do the researchers say about the search?

Pirrie said the investigation leaves the team far better equipped to focus on the areas most likely to yield an answer.

Professor Nick Pearce of Aberystwyth University, a geochemistry expert who worked on the earlier research, took a similar view. He said that “ruling out potential source areas is just as important as identifying new ones.” In his words, every location eliminated narrows the search and brings researchers closer to finding where the stone began its journey.

Why does the Altar Stone stand out at Stonehenge?

Pearce said the Altar Stone is unique among the stones at Stonehenge. The BBC noted that the Wiltshire monument was built in multiple phases between 3000 and 1600 B.C., and that not all of its stones come from the local area.

The smaller bluestones, for example, traveled around 225km from west Wales. Research suggests a few of them were taken directly from another circle. The Altar Stone's own route to Salisbury Plain is still unexplained.

Why does it matter?

The result has no direct effect on daily life, but it bears on one of the best-known puzzles about a world-famous monument. Pearce said that tracing the stone's source would provide valuable new insights into its remarkable journey to Salisbury Plain thousands of years ago.

For now, the finding narrows the possibilities rather than solving the mystery. Researchers describe each ruled-out region as progress, since it lets them concentrate on places that remain plausible. Neither the BBC report nor the researchers named a new candidate location.

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Around Prague, based on reporting by BBC News