THE six-tonne Altar Stone at Stonehenge travelled further to its resting place than first thought, new research has revealed.
It's been believed the Alter Stone originated from Wales for the past century, but new findings published today rewrite that version of history.
The giant rock, partially buried beneath two fallen stones of the largest trilithon, was actually lugged all the way from Scotland, according to researchers at Curtin University, in Australia.
That is at least 750 kilometres from its final resting place on the Salisbury Plain, in Wiltshire, England.
The Alter Stone is the largest of the non-sarsen stones, and was thought to have come from the Brecon Beacons area of south-east Wales, some 210 kilometres away.
It is a whopping 50cm thick sandstone block measuring 5x1 metres, and scientists say it may have been placed within the central horseshoe of stones during the second construction phase at about 2620–2480 BC.
While analysing the age and chemistry of the mineral grains in the rock, researchers discovered that fragments of the Alter Stone matched with rocks from northeast Scotland.
The rock composition was different to other Welsh bedrock that the researchers analysed.
The majority of Stonehenge’s bluestones came from the Preseli Hills area in west Wales and are believed to have been the first stones erected at the site.
Figuring out how the ancient stones arrived in Wiltshire 5,000 years ago, and where they came from, has mystified researchers for centuries.
But today's findings point to an even more advanced transport method than what had been assumed, as well as a greater level of societal organisation.
“Our analysis found specific mineral grains in the Altar Stone are mostly between 1000 to 2000 million years old, while other minerals are around 450 million years old,” said Anthony Clarke, PhD student and lead author of the study at Curtin University.
“This provides a distinct chemical fingerprint suggesting the stone came from rocks in the Orcadian Basin, Scotland, at least 750 kilometres away from Stonehenge.
“Given its Scottish origins, the findings raise fascinating questions, considering the technological constraints of the Neolithic era, as to how such a massive stone was transported over vast distances around 2600 BC."
It's a question that has baffled researchers for centuries.
There are two types of stone at Stonehenge - the larger sarsen stones and the smaller ‘bluestones’.
The sarsens weigh roughly 25 tons each, with the largest stone, the Heel Stone, weighing about 30 tons.
The most popular theory suggests the rocks were moved into position using plant fibre ropes and a wooden A-frame.
Another theory, inspired by the Easter Island rock heads, argues the Stonehenge slabs were rocked from side to side with levers.
Co-author of the study, Professor Richard Bevins from Aberystwyth University, said that important questions regarding the origin of the stones still remain.
“We have succeeded in working out, if you like, the age and chemical fingerprints of perhaps one of the most famous of stones in the world-renowned ancient monument," he said.
“While we can now say that this iconic rock is Scottish and not Welsh, the hunt will still very much be on to pin down where exactly in the north-east of Scotland the Altar Stone came from.”
Why and how the Alter Stone was moved from Scotland to Wiltshire also remains a mystery.
Fellow co-author Dr Robert Ixer of the UCL Institute of Archaeology added: “The work prompts two important questions: why and exactly how was the Altar Stone transported from the very north of Scotland, a distance of more than 700 kilometres, to Stonehenge?”
What you need to know about Britain's most mysterious monument
