00:00A new discovery concerning Britain's famous Stonehenge monument has stunned researchers.
00:07Its altar stone, weighing an estimated six tonnes, travelled roughly 435 to 465 miles
00:15in ancient times, from Scotland all the way to England's Salisbury Plain.
00:21New research, published in the journal Nature, was carried out by scientists at Aberystwyth
00:25University, UCL, Curtin University and the University of Adelaide.
00:31However you brought it, whether you brought it down by boat or whether you brought it
00:35over land, yeah, it must have taken a huge effort to do that.
00:39Nick Pearce is a geologist and co-author of the study.
00:43And it sits right at the centre of the Stonehenge monument. It's the bit that you stand on to
00:47watch the sunrise between the other stones over there. So it's right at the middle. So
00:51it must have been placed there as an important stone.
00:54The origin and purpose of the altar stone have been among the mysteries of the megalithic
00:58monument. For the past century, the common belief had been that it had been sourced from
01:03Wales, like other large components at the UNESCO World Heritage Site.
01:08To find out the age of the stone, researchers studied its geochemical fingerprint.
01:14It's a micro-analysis technique. You fire a very focused laser beam on the minerals
01:20in the rock and it vaporises them. You analyse the vapour and you analyse the uranium concentrations
01:27and the lead concentrations.
01:29They found that the minerals of the altar stone are a perfect match for bedrock found
01:34in north-eastern Scotland.
01:35And you analyse 50 or 60 minerals and you get this fingerprint of the different ages
01:41of those minerals in the rock. And that's the characteristic that tells us this is Orcadian
01:46based. It's that age, that suite of ages from those individual minerals in the grains
01:51of the altar stone.
01:53No stone from any other monument dating back to that time period is known to have been
01:58transported so far.
02:00Researchers say this feat, perhaps by both land and sea, suggests a degree of societal
02:05organisation among Britain's Neolithic communities unexpected for the time when it was moved,
02:11thought to have been about 4,600 to 2,500 years ago.
02:16The precise location where the altar stone was sourced remains unknown.
02:20But researchers say the challenge of taking such a massive cargo such a long distance
02:25underscores its importance to Stonehenge's builders.
02:29The monument was built in multiple stages over 500 years or so, starting about 3000
02:35BC.
02:36It remains a site of fascination and mystery over its exact purpose, drawing tourists from
02:42around the world.
02:46For more information visit www.nasa.gov
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