London: Scientists in Britain have at long last unravelled the riddle about the origin of the Stonehenge rocks, pinpointing their source to north Pembrokeshire.
Geologists Robert Ixer from the University of Leicester and Richard Bevins of the National Museum of Wales suggest the stones came from Craig Rhos-y-Felin, in north Pembrokeshire.
The discovery paves the way for better understanding of how and why the stones were transported to the Wiltshire monument.
Controversy has raged over the origin of the Bluestones or `spotted dolerites`-- that form the inner circle and inner horseshoe of the 5,000-year-old site.
There is a consensus that the large stones, the sarsens, were added hundreds of years later.
Bevins said: "It has been argued that humans transported the spotted dolerites from the high ground of Mynydd Preseli down to the coast at Milford Haven and then rafted them up the Bristol Channel and up the River Avon to the Stonehenge area."
"However, the outcome of our research questions that route, as it is unlikely that they would have transported the Pont Season stones up slope and over Mynydd Preseli to Milford Haven. If humans were responsible, then an alternative route might need to be considered."
"However, some believe that the stones were transported by the actions of glacier sheets during the last glaciation and so the Pont Season discovery will need appraising in the context of this hypothesis," Bevins said.
Bevins describes his discovery as like `looking for a needle in a haystack`, but is convinced it`s correct. "We`ve been able to make the match on a range of features, not just a single characteristic."
Rob Ixer added: "Being able to provenance any archaeologically significant rock so precisely is remarkable, to do it for Stonehenge was quite unexpected and exciting.
Stonehenge expert Vince Gaffney, from the IBM Visual and Spatial Technology Centre at the University of Birmingham, underlined the importance of the discovery.
"Dr Ixer`s research is a significant contribution to our understanding of Stonehenge and the intricate social networks that lay behind the construction of this unique monument."