thinking about archaeology

Have archaeologists found Stonehenge quarries?

Bluestone open spread.jpgThey certainly think so – not all, but two important ones. I went to visit their excavations in Pembrokeshire this summer, and was sufficiently impressed to ask them to write about their discoveries for British Archaeology. You can read their report with many photos – including this fabulous opening shot by Adam Stanford – in the new magazine later this week. Digital on Wednesday December 9 (as an App and in web form) and print in the shops on Friday. Copies for Council for British Archaeology members and magazine subscribers are on their way.

Carn Goedog M Pitts.jpg

Excavations at Carn Goedog (photo M Pitts)

In the meantime, here is the UCL press release.

Stonehenge ‘bluestone’ quarries confirmed 140 miles away in Wales

Excavation of two quarries in Wales by a UCL-led team of archaeologists and geologists has confirmed they are sources of Stonehenge’s ‘bluestones’– and shed light on how they were quarried and transported.

New research by the team published today in Antiquity presents detailed evidence of prehistoric quarrying in the Preseli hills in Pembrokeshire, helping to answer long-standing questions about why, when and how Stonehenge was built.

The team of scientists includes researchers from UCL, University of Manchester, Bournemouth University, University of Southampton, Amgueddfa Cymru – National Museum Wales, and Dyfed Archaeological Trust.

The very large standing stones at Stonehenge are of ‘sarsen’, a local sandstone, but the smaller ones, known as ‘bluestones’, come from the Preseli hills in the Pembrokeshire Coast National Park. Geologists have known since the 1920s that the bluestones were brought to Stonehenge from somewhere in the Preseli Hills, but only now has there been collaboration with archaeologists to locate and excavate the actual quarries from which they came.

Director of the project, Professor Mike Parker Pearson (UCL Institute of Archaeology), said: “This has been a wonderful opportunity for geologists and archaeologists to work together. The geologists have been able to lead us to the actual outcrops where Stonehenge’s stones were extracted.”

The Stonehenge bluestones are of volcanic and igneous rocks, the most common of which are called dolerite and rhyolite. Dr Richard Bevins (Amgueddfa Cymru – National Museum Wales) and Dr Rob Ixer (UCL and University of Leicester) have identified the outcrop of Carn Goedog as the main source of Stonehenge’s ‘spotted dolerite’ bluestones and the outcrop of Craig Rhos-y-felin as a source for one of the ‘rhyolite’ bluestones. The research published today details excavations at Craig Rhos-y-felin specifically.

The special formation of the rock, which forms natural pillars at these outcrops, allowed the prehistoric quarry-workers to detach each megalith (standing stone) with a minimum of effort. “They only had to insert wooden wedges into the cracks between the pillars and then let the Welsh rain do the rest by swelling the wood to ease each pillar off the rock face” said Dr Josh Pollard (University of Southampton). “The quarry-workers then lowered the thin pillars onto platforms of earth and stone, a sort of ‘loading bay’ from where the huge stones could be dragged away along trackways leading out of each quarry.”

Professor Colin Richards (University of Manchester), an expert in Neolithic quarries, said: “The two outcrops are really impressive – they may well have had special significance for prehistoric people. When we saw them for the first time, we knew immediately that we had found the source.”

Radiocarbon-dating of burnt hazelnuts and charcoal from the quarry-workers’ camp fires reveals that there were several occurrences of megalith-quarrying at these outcrops. Stonehenge was built during the Neolithic period, between 4,000 to 5,000 years ago. Both of the quarries in Preseli were exploited in the Neolithic, and Craig Rhos-y-felin was also quarried in the Bronze Age, around 4,000 years ago.

“We have dates of around 3400 BC for Craig Rhos-y-felin and 3200 BC for Carn Goedog, which is intriguing because the bluestones didn’t get put up at Stonehenge until around 2900 BC” said Professor Parker Pearson. “It could have taken those Neolithic stone-draggers nearly 500 years to get them to Stonehenge, but that’s pretty improbable in my view. It’s more likely that the stones were first used in a local monument, somewhere near the quarries, that was then dismantled and dragged off to Wiltshire.”

Professor Kate Welham (Bournemouth University) thinks that the ruins of any dismantled monument are likely to lie somewhere between the two megalith quarries. She said: “We’ve been conducting geophysical surveys, trial excavations and aerial photographic analysis throughout the area and we think we have the most likely spot. The results are very promising – we may find something big in 2016.”

The megalith quarries are on the north side of the Preseli hills, and this location undermines previous theories about how the bluestones were transported from Wales to Stonehenge. Previous writers have often suggested that bluestones were taken southwards from the hills to Milford Haven and then floated on boats or rafts, but this now seems unlikely.

“The only logical direction for the bluestones to go was to the north then either by sea around St David’s Head or eastwards overland through the valleys along the route that is now the A40” said Professor Parker Pearson. “Personally I think that the overland route is more likely. Each of the 80 monoliths weighed less than 2 tons, so teams of people or oxen could have managed this. We know from examples in India and elsewhere in Asia that single stones this size can even be carried on wooden lattices by groups of 60 – they didn’t even have to drag them if they didn’t want to.”

Phil Bennett, Pembrokeshire Coast National Park Authority’s Culture and Heritage Manager, said: “This project is making a wonderful contribution to our knowledge of the National Park’s importance in prehistory.”

The new discoveries may also help to understand why Stonehenge was built. Parker Pearson and his team believe that the bluestones were erected at Stonehenge around 2900 BC, long before the giant sarsens were put up around 2500 BC.

“Stonehenge was a Welsh monument from its very beginning. If we can find the original monument in Wales from which it was built, we will finally be able to solve the mystery of why Stonehenge was built and why some of its stones were brought so far”, said Professor Parker Pearson.

Further excavations are planned for 2016.

“Craig Rhos-y-felin: a Welsh bluestone megalith quarry for Stonehenge” is published in the journal Antiquity today.

bluestones Antiquity.jpgAnd the new CBA book:

Stonehenge CBA book

7 responses

  1. Reblogged this on Stonehenge News and Information.

    December 7, 2015 at 8:59 am

  2. Pingback: Have archaeologists found Stonehenge quarries? | The Heritage Trust

  3. Dr Nick

    Reblogged this on FragmeNTs and commented:
    Mike Pitts on the latest findings, published in Antiquity today, from Mike Parker Pearson’s team’s work on the origins of the Stonehenge Bluestones.

    December 7, 2015 at 11:24 am

  4. No place on your report for the other radio carbon dates from the Mesolithic at 8,500 BCE (same date as the Stonehenge visitors car park post hole) or the 7,000 BCE hearth dates – both of which are closer to the carbon-36 dating of the bluestone nobody in the academic world wishes to comment upon nowadays – A bit too much science for the archaeological community which seems to thrive more on speculation rather than facts?

    Perhaps MPP will come up with the same nonsensical story (if he ever talks about the Mesolithic dates) similar to the ones still used for Stonehenge’s old visitors car park of ‘passing nomads’ as a reason for the earlier visits – such as “just so happens the quarry has a killer view for a picnic”? or go back to the normal ‘religious sacred site’ mumbo jumbo that seems to dominate archaeologies poor and scientifically flawed analytical work.

    Robert John Langdon

    December 10, 2015 at 12:40 pm

  5. Mandy

    Mr Pitts, I just today, read in the telegraph about scientists in wales who refute the work of the UCL team, stating their excavations at rhos y fellin were selective and that the evidence is more in favor of glaciers moving the stones (to salisbury?) rather than man. I wondered what your thoughts were about the credibility of their argument.

    December 20, 2015 at 6:26 am

    • mikepitts

      Hi Mandy. I have an open mind on this, and await the full evidence from all sides. There are two arguments here. A very long-standing dispute is between those who think the Welsh bluestones at Stonehenge were all taken to Salisbury Plain (or nearby) by glaciers, and those who think people brought them in. I’m not a geologist or geomorphologist, but the case for glaciers has always seemed to me extremely weak (basically, there seems to be no evidence). The immediate dispute is about recent excavations in Pembrokeshire, and whether or not the two outcrops noted above show evidence for neolithic quarrying. To date the evidence from both sides can be questioned. Note of course that whether or not these particular outcrops prove to be quarries, does not remove the possibility of future quarries being found elsewhere in the area.

      August 23, 2016 at 9:46 am

  6. brianjohn891

    Mike — “there seems to be no evidence” in the case for glacial transport? Quite wrong. Please read the literature. There are glacial deposits in Somerset and in the Bath area. One of the Somerset locations contains an erratic of white limestone from Northern Ireland. Ice has reached the Scilly Islands on at least two occasions. There are Pembrokeshire erratics in Glamorgan, and Scottish erratics on the coasts of Devon and Cornwall. The real question is “how far east did the Irish Sea Glacier penetrate into Somerset and Wiltshire?” In contrast, there is no evidence whatsoever for the human transport of Pembrokeshire erratics into Wiltshire. Experimental archaeology is very jolly, but it is not evidence. You might say “We know that men can move stones” and I might say “We know that glaciers can move erratics” — and we are no further forward. Forget about the transport issue, which is unresolved. What we need to do is just look at these rock outcrops in Pembrokeshire, which in our view contain no evidence whatsoever of quarrying activity.

    September 17, 2016 at 6:35 pm

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