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The University of Southampton

Quarrying of Stonehenge ‘bluestones’ dated to 3000 BC

Published: 1 March 2019
Quarry site at Carn Goedog, Wales
Quarry site at Carn Goedog, Wales. Credit: UCL

Excavations at two quarries in Wales, known to be the source of the Stonehenge ‘bluestones’, provide new evidence of megalith quarrying 5,000 years ago, according to a new study by a UK research team, including archaeologists from the University of Southampton.

Geologists have long known that 42 of Stonehenge’s smaller stones, known as ‘bluestones’, came from the Preseli hills in Pembrokeshire, west Wales. Now a new study published in the journal Antiquity pinpoints the exact locations of two of these quarries and reveals when and how the stones were quarried.

The discovery has been made by archaeologists and geologists led by UCL – working the University of Southampton, Bournemouth University, the University of the Highlands and Islands and the National Museum of Wales. The team has been investigating the sites for eight years.

The largest quarry was found almost 180 miles away from Stonehenge on the outcrop of Carn Goedog, on the north slope of the Preseli hills. This was the dominant source of Stonehenge’s spotted dolerite, so-called because it has white spots in the igneous blue rock. At least five of Stonehenge’s bluestones, and probably more, came from Carn Goedog.

In the valley below Carn Goedog, another outcrop at Craig Rhos-y-felin was identified by Dr Richard Bevins (National Museum of Wales) and fellow geologist Dr Rob Ixer (UCL) as the source of one of the types of rhyolite – another type of igneous rock – found at Stonehenge.

Stone pillars
Stone pillars. Credit: UCL

Leader of the team, Professor Mike Parker Pearson of UCL said: “What’s really exciting about these discoveries is that they take us a step closer to unlocking Stonehenge’s greatest mystery – why its stones came from so far away.

“Every other Neolithic monument in Europe was built of megaliths brought from no more than 10 miles away. We’re now looking to find out just what was so special about the Preseli hills 5,000 years ago, and whether there were any important stone circles here, built before the bluestones were moved to Stonehenge.”

Archaeologist Dr Joshua Pollard of the University of Southampton adds: “This research is further confirmation that the Stonehenge bluestones were moved in prehistory by people, rather than by geological forces such as ice-sheets. The transportation of these massive slabs of rock stands out as one of the most remarkable instances of long-distance movement of large stones in the ancient world.

“This demonstrates how early farmers, settled in what is now Wiltshire, had a strong connection to their ancestral lands in Wales and needed to reinforce those connections through the movement and building of a great megalithic monument.”

According to the new study, the bluestone outcrops are formed of natural, vertical pillars. These could be eased off the rock face by opening up the vertical joints between each pillar. Unlike stone quarries in ancient Egypt, where obelisks were carved out of the solid rock, the Welsh quarries were easier to exploit. Neolithic quarry workers needed only to insert wedges into the ready-made joints between pillars, then lower each pillar to the foot of the outcrop.

Although most of their equipment is likely to have consisted of perishable ropes and wooden wedges, mallets and levers, they left behind other tools such as hammer stones and stone wedges.

Site at Craig-Rhos-y-felin
Site at Craig-Rhos-y-felin. Credit: UCL/SRP/SOS/Adam Stanford

Archaeological excavations at the foot of both outcrops uncovered the remains of man-made stone and earth platforms, with each platform’s outer edge terminating in a vertical drop of about a metre. Bluestone pillars could be eased down onto this platform, which acted as a loading bay for lowering them onto wooden sledges before dragging them away.

An important aim of the research was to date megalith-quarrying at the two outcrops. In the soft sediment of a hollowed-out track leading from the loading bay at Craig Rhos-y-felin, and on the artificial platform at Carn Goedog, the team recovered pieces of charcoal dating to around 3000 BC.

The team now thinks that Stonehenge was initially a circle of rough, unworked bluestone pillars set in pits known as the Aubrey Holes, near Stonehenge, and that the sarsens (sandstone blocks) were added some 500 years later.

The new discoveries also cast doubt on a popular theory that the bluestones were transported by sea to Stonehenge – taken southwards to Milford Haven, paddled up the Bristol Channel and along the Bristol Avon towards Salisbury Plain. But these quarries are on the north side of the Preseli hills, so the megaliths could have gone overland to Salisbury Plain.

The research was funded by the British Academy, the Natural Environment Research Council (NERC), the National Geographic Society, the Society of Antiquaries, the Royal Archaeological Institute and the Cambrian Archaeological Association.

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