Stonehenge. Image: Wikipedia.

(PhysOrg.com) — Robert Ixer and Richard Bevins, British geologists, after nine months of tedious research, have pinpointed the place from which some of the stones that make up Stonehenge were quarried. The stones in question, the so-named bluestones, the smaller kind used in the inner circle at Stonehenge, came from a sixty five meter long outcropping called Craig Rhos-y-Felin, which is close to the town of Pont Saeson in the north part of Pembrokeshire, in Wales; a site some one hundred and sixty miles from Stonehenge. The question now is, did the early Neolithic people who built Stonehenge bring them to the site over 5000 years ago, or was it due to natural causes, such as glacial movement?

That question may soon be answered as further research is conducted at the quarry site. If evidence can be found of human quarrying, little doubt will remain that the huge, four tonne stones were either loaded onto barges and sent around St. David’s Head or carted directly across the mountainous terrain that sits between Stonehenge and the quarry site.

The researchers found the quarry site by a collecting and analyzing rocks in Pembrokeshire, looking for a match with the rhyolite debitage rocks at Stonehenge. When close matches were found, they took a closer look using petrography, a means for comparing mineral content. They kept up their search till they found specimens that were 99% identical to those at Stonehenge, a sure sign that the two were from the same place. The two believe their findings mean they have pinpointed the place where the Stonehenge rocks came from to within seventy meters.

News of the find has been greeted with excitement the world over – such is the connection people feel with the mystery that is Stonehenge, the circular monument believed to have been built from the period 3000 BC to 1600 BC by early people for an unknown reason. The outer bigger stones, called sarsens, are believed by most archeologists and historians to have been hauled to the site some two hundred years after the bluestones, and came from a much closer place; somewhere in Marlborough Downs, just twenty miles to the north.

If it can be proven that the rocks were in fact quarried by people, likely many other scientists will join in the debate that will no doubt ensue in attempting to explain how such a primitive people could have achieved such a feat as transporting such big and heavy stones such a great distance, and why.

© 2011 PhysOrg.com

from:    http://www.physorg.com/news/2011-12-geologists-exact-source-stonehenge-stones.html