Archaeological investigators from National Museum Wales say "99%" of rhyolite rocks found at Stonehenge can be matched to ones found in a 70-metre stretch of land in North Pembrokeshire.
© English Heritage
The institution's Dr Richard Bevins and Dr Rob Ixer, of Leicester University, spent nine months collecting samples from rock outcrops at the Craig Rhos-y-felin site, near the prehistorically lucrative Pont Saeson region, in a bid to discover the origins of boulders at the Wiltshire landmark.
The "distinctly different" make-up of the rocks allowed them to be pinpointed to precise sections of the area measuring only a few metres in size.
Experts are now planning to excavate the grounds for evidence of human activity which could yield important conclusions about how the rocks were transported across the border.
"Many have asked the question over the years – how did the stones got from Pembrokeshire to Stonehenge?" said Dr Bevins.
"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."
"Being able to provenance any archaeologically significant rock so precisely is remarkable," added Dr Ixer.
"To do it for Stonehenge was quite unexpected and exciting.
"Given continued perseverance, we are determined that we shall uncover the origins of most, if not all of the Stonehenge bluestones, allowing archaeologists to continue their speculations well into a third century."
The findings have been published in annual report Archaeology in Wales.