How miners quarried the pillars of Stonehenge

Some of the massive rocks of Stonehenge might have been first erected as a monument in west Wales, some 230 kilometres away, archaeologists suggest.

In a paper published in the journal Antiquity, researchers led by Mike Parker Pearson of University College London, England, reveal the likely Neolithic quarries from which several of Stonehenge’s iconic “bluestone” pillars were extracted.

They also identify tools used in the process, and thus reconstruct the mining and removal protocols, and build on earlier research that indicates at least some of the giant standing stones were initially incorporated into a stone circle not far from their point of origin.

The bluestone pillars, which comprise an inner “horseshoe” and outer circle at Stonehenge, are made from spotted dolerite. As early as 1923 it was established that the only place in Britain this type of rock can be found is in the Preseli Hills – also known as Mynydd Preseli – in the north Pembrokeshire area of west Wales.

The area is home to several ancient quarries, however, each yielding rocks with differing visual and chemical attributes, and it soon became clear that the enormous monument in Wiltshire contained pillars for more than one location.

The task of assigning specific stones to specific points of origin has been ongoing ever since.

In the latest work, Pearson and colleagues successfully locate the origins of several of the bluestones to two Neolithic quarries, called Carn Goedog and Craig Rhos-y-Felin.

The extraction of stone in the Preseli Hills continued through later periods, including the Roman and Medieval, and in some instances was still taking place in the nineteenth century. However, the archaeologists identified parts of Carn Goedog and Craig Rhos-y-Felin that had apparently been left untouched since shortly after the Stonehenge pillars were removed, about 3000BCE.

As a result, they were able to make some evidence-based deductions about how the mining process worked.

At Carn Goedog the researchers found a number of stone tools. The most common of these were large wedges, made from mudstone or sandstone (neither endemic to the area). Pearson and colleagues suggest that these wedges were inserted into vertical cracks in the dolerite, then forced down to separate a thus naturally formed pillar from its parent rock.

The use of mudstone and sandstone to make the wedge-stools, the archaeologists suggest, is significant. Both types of rock are softer than dolerite, and were perhaps used to ensure that when stresses built it would be the tools rather than the pillars that cracked.

Based on observations of low-tech quarrying practices still going on in other parts of the world, it is likely that the stone tools were augmented with wooden wedges, levers and ropes. However, none of this organic matter has survived.

Clearing away stone debris at the base of Carn Goedog, the archaeologists discovered a large platform, built from flat stone slabs, many of them cracked.

This, they suggest, served as the landing stage for the newly extracted pillars.

“Once a pillar was loosened from the rock face using wedges, ropes could be secured around its upper section so that it could be pulled outwards from the rock face, being steadied by ropes held by workers standing on the wide, level summit of the outcrop,” they write.

“Those on top of the outcrop could have carefully payed out their ropes to control the pillar’s descent so that it slowly pivoted down into the artificial platform, its tip pressing some of the platform’s stone slabs deep into the soil beneath. Ropes could then be reattached to lower the pillar to a horizontal position.”

From there – perhaps resting on timbers – the pillar could have been levered onto a waiting wooden sledge, and then dragged across the ground, sliding across dry grass.

The archaeologists identify a couple of potential routes away from the two quarry sites. In so doing, they refer to a large body of earlier research – or perhaps speculation – some of it dating back a century, that suggests the bluestones were first incorporated into a gigantic stone circle much closer to their point of origin.

This putative monument, the archaeologists say, was the “original Stonehenge”.

One oft-cited possible location is a nearby Neolithic enclosure called Banc Du. Earlier research established that the area was in use at roughly the same time the Stonehenge pillars were quarried, but geophysical analysis failed to find any evidence of “cultural features”, implying it was just a storage area.

Another candidate is an ancient enclosure called Dryslwyn, in the lower Nevern Valley, which is known to have been palisaded and contains a single-chamber megalithic tomb known as a dolmen.

Pearson and colleagues do not discount this as a possibility. They add, however, another candidate – a locality known as Waun Maun, just three kilometres from the quarry sites and known to contain a partial stone circle.

The place was first suggested as the location of what might be thought of as the prototype Stonehenge as early as 1925, but was discounted by other archaeologists in the 1960s. The identification of Carn Goedog and Craig Rhos-y-Felin as the source of known Stonehenge pillars, however, Pearson and colleagues say, should prompt a re-examination of the site.

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