Geologists and archaeologists have long known that the bluestones of Stonehenge came from the Preseli Hills of west Wales, 230km away, but only recently have some of their exact geological sources been identified. Two of these quarries—Carn Goedog and Craig Rhos-y-felin—have now been excavated to reveal evidence of megalith quarrying around 3000 BC—the same period as the first stage of the construction of Stonehenge. The authors present evidence for the extraction of the stone pillars and consider how they were transported, including the possibility that they were erected in a temporary monument close to the quarries, before completing their journey to Stonehenge.

The long-distance transport of the bluestones from south Wales to Stonehenge is one of the most remarkable achievements of Neolithic societies in north-west Europe. Where precisely these stones were quarried, when they were extracted and how they were transported has long been a subject of speculation, experiment and controversy. The discovery of a megalithic bluestone quarry at Craig Rhos-y-felin in 2011 marked a turning point in this research. Subsequent excavations have provided details of the quarrying process along with direct dating evidence for the extraction of bluestone monoliths at this location, demonstrating both Neolithic and Early Bronze Age activity.

Recent investigations at Stonehenge have been accompanied by new research on the origin of the famous ‘bluestones’, a mixed assemblage of rhyolites and dolerites that stand among the much taller sarsens. Some of the rhyolite debitage has been traced to a quarry site at Craig Rhosyfelin near the Pembrokeshire coast; but fieldwork on the upland outcrops of Carn Menyn has also provided evidence for dolerite extraction in the later third millennium BC, and for the production of pillar-like blocks that resemble the Stonehenge bluestones in shape and size. Quarrying at Carn Menyn began much earlier, however, during the seventh millennium BC, suggesting that Mesolithic communities were the first to exploit the geology of this remote upland location.