December 20, 2011
Researchers Confirm Origin Of Stonehenge Rocks
Experts studying the mysteries surrounding Stonehenge have now confirmed for the first time the exact origin of some of the rocks used in the ancient monument in Wiltshire, England.
The researchers -- geologists Robert Ixer of the University of Leicester and Richard Bevins of the National Museum of Wales -- have matched fragments of stone from the 5,000 year old monument with rocks found in southwest Wales more than 150 miles away. The actual site of the source is Craig Rhos-y-Felin, near Pont Saeson in north Pembrokeshire.Bevins and Ixer have spent nine months collecting and identifying samples of rock outcrops in Pembrokeshire to try to find a match to the rocks of Stonehenge. By detailing the mineral content and the textural relationships within the rock, they were able to find 99 percent of the samples could be matched to the rocks found in the Pembrokeshire outcrop.
The rhyolitic rocks at Rhos-y-Felin differ from all others found in South Wales, the team said, which helps locate all of Stonehenge´s rhyolites to within hundreds of square feet. The rocks in Rhos-y-Felin differ from one another even on a scale of tens of feet, allowing Bevin and Ixer to match some of Stonehenge´s samples even more precisely to the extreme northeastern end of Rhos-y-Felin.
The find is “quite unexpected and exciting,” said Ixer. “Being able to provenance any archaeologically significant rock so precisely is remarkable.”
“However, given continued perseverance, we are determined that we shall uncover the origins of most, if not all of the Stonehenge bluestones so allowing archaeologists to continue their speculations well into a third century,” he told BBC News.
With the location of the source now revealed, archaeologists will now be able to unearth how the stones from Pembrokeshire reached Stonehenge.
“Many have asked the question over the years, how the stones got from Pembrokeshire to Stonehenge,” Bevins told BBC “Was it human transport? Was it due to ice transport?”
“Thanks to geological research, we now have a specific source for the rhyolite stones from which to work and an opportunity for archaeologists to answer the question that has been widely debated. It is important now that the research continues,” Bevins told BBC News.
The debate is solely about Stonehenge´s smaller standing stones which are sometimes known collectively as bluestones. The larger stones (sarsens) are accepted to have been incorporated into the monument several centuries later.
Archaeologists have long suspected that the 82 bluestones, each weighing up to 5 tons, came from the northern Preseli Hills in Wales. But now with a precise match of where they did come from, researchers can look for evidence on how the massively heavy stones were transported over such a great distance.
One theory suggests the rocks were not transported by humans at all but by the movement of glaciers during the Ice Age several millennia earlier. Although, the absence of any other Welsh rock in the region seems to debunk this theory.
Other theories also suggest that man moved the slabs up the Bristol Channel and River Avon via rafts, and perhaps rolled them across logs when on dry land. However, some have questioned this perceived method due to the extremely rough terrain the slabs would have to have been transported over.
This method was further questioned after a National Heritage Lottery Fund plan, launched in April 2000 to replicate the journey of the giant stone from Wales to Salisbury Plain in Wiltshire, by way of land, sea, and only the technology of the ancients, ended in disaster when the stone sank in Milford Haven estuary.
However the rocks made the journey from Pembrokeshire to Wiltshire, the find, reported in the journal Archaeology in Wales, has been called a “scientific triumph” by Stonehenge expert Professor Geoff Wainwright, former chief archaeologist at English Heritage.
“It does not discredit any previous work, it gives archaeologists an area to focus on,” he said. “It´s still something of a mystery but we are now a step closer to getting the answers.”
“This is very interesting and narrows the search down, but the Holy Grail is to find a stone along the way, which could have dropped off the sledge, which could show us how it was achieved,” archaeologist Julian Richards, presenter of the BBC´s Meet the Ancestors, told the Daily Mail.
One thing is for sure -- experts are unclear on why Stonehenge´s builders would transport such particular rocks from more than 150 miles away. Maybe they believed they were obtaining more than just plain rock. Experts have suggested Stonehenge crafters regarded the bluestones as having supernatural powers.
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