Today, Stonehenge is one of the most well-known Neolithic monuments in the world. It has become a standout example of prehistoric, megalithic architecture. But the story of the stones themselves, and how they reached this Wiltshire plain, is perhaps most extraordinary of all.
Broadly speaking, there are two types of stones at Stonehenge. Firstly, there are the sarsens. These are the gigantic megaliths largely (if not all) sourced from the Marlborough Downs.
Within the sarsen circle, however, is a collection of smaller, darker and more mysterious stones. Some are standing. Others lie on their side, including the well-known ‘Altar Stone’ in the centre. Collectively, these stones are known as bluestones. As archaeologist and author Mike Pitts says, “if the sarsens are the crown of Stonehenge, the bluestones are its jewels.”
But how did these stones make their way to Wiltshire, and where exactly did they come from?
Where did they come from?
In the 19th century, antiquarians put forward various theories as to where Stonehenge’s bluestones originated from. Theories varied from Dartmoor to the Pyrenees, and from Ireland to Africa. But then, in the early 20th century, came Herbert Henry Thomas.
Thomas recognised that the stones were dolerite, a rare igneous rock that was also found in Pembrokeshire, in the Preseli Hills in Southwest Wales. From this, Thomas was able to conclude that Stonehenge’s mysterious bluestones had originated from the Preseli Hills.
Thomas went on to do further research on the stones. He ultimately proposed several particular dolerite outcrops from the Preselis as the sources of Stonehenge’s bluestones. Many of these outcrop suggestions have not stood the test of time. Although modern research still supports his belief that the dolerite outcrop of Cerrig Marchogion was one such source, there is more uncertainty around the other sites Thomas suggested (for instance Caryn Menyn).
Today, several outcrops in the Preselis have been identified as sources of Neolithic megaliths. Most of these lie along the Hills’ northern slopes. These outcrops include Carn Goedog, Carn Gyfrwy, Carn Breseb and a small rhyolite outcrop at Craig Rhos-y-Felin, slightly north of the Preseli Hills. Rhyolite is another type of igneous rock that was also found among the Stonehenge bluestones.
The Altar Stone is an exception. Archaeologists and geologists have long debated its origins. But many now believe that it originated from east of the Preseli Hills, towards the Brecon Beacons and closer to the English border.
How did they get to Wiltshire?
So if we know the source of the bluestones, the next question has to be: how did they reach Wiltshire? One theory is that glaciers carried these megaliths to Salisbury Plain during an earlier era. Today, however, this is a minority view.
Most believe that the Preseli Hills’ bluestones were transported to Wiltshire by Neolithic people. This in itself deserves special mention. Most Neolithic megaliths were local stones, so the fact that the Stonehenge bluestones originated so far away from the final site is extraordinary. It further affirms how culturally significant the building of this iconic monument was to surrounding communities: it was so important that they were willing to source the bluestones from very far away.
But how did these Neolithic people transport the stones to Wiltshire? Various routes have been put forward. One theory is that the stones were shipped to Wiltshire.
The theory centres around people moving the megaliths down to the Welsh south coast, near modern-day Milford Haven. There, it is argued, the stones were loaded onto boats and shipped to Wiltshire by sea. This sea journey would have been difficult, especially when sailing around Land’s End.
That being said, we do have indirect evidence for sophisticated engineers and boat builders living in Britain during the Neolithic period, capable of constructing durable craft that could sail through these waters. Said evidence is the remains of a few bronze age boats that have survived. Their complexity suggests that the boats in the preceding Neolithic were similarly capable.
This, however, does not confirm that the stones were transported to Stonehenge by the sea route. Rather, it suggests that boats were capable of transporting megaliths at the time of Stonehenge’s construction and that the sea journey is a viable possibility.
An alternate argument is that the journey between the Preselis and Wiltshire was an overland route. Another suggests a combined land and sea route, centred around several river valleys in Wales and southwest England. This latter theory has been put forward in detail by Mike Pitts in his new book, How to Build Stonehenge.
Moving the stones
These are the possible routes that archaeologists have touted. But how were the stones moved? Experimental archaeology suggests that the key machinery used for moving the stones was a sledge, upon which each megalith was placed.
Those transporting the stones would have placed strong ropes at the front, back and sides of the sledge to help move it. Meanwhile, piles of long, thin timbers would be placed on the ground in front of the sledge, over which the transporters would move the stone. Hundreds of levers would also be used.
Another archaeological feature to highlight is the solid, timber tracks that we know were present in Neolithic Britain. It’s very possible that these permanent, wooden walkways were used to help transport the stones along certain parts of their journey to Wiltshire.
Draught animals were possibly also used to help transport the stones, but Mike Pitts has argued against this, writing, “at megalith construction events, cattle are more likely to be sacrificed than put to work, not least because the opportunity for people to do the labouring is of great social significance.”
One way that these people almost certainly did not move the megaliths was with timber ‘rollers’. Although they have featured in certain reconstructions, experimental archaeology has proven how difficult rollers were to use. Not only did the transported stone tend to slip off, but the rollers were also incredibly difficult to use in rougher terrain. And there is plenty of rough terrain between the Preseli Hills and Wiltshire.
A new, proposed route
Based on the available information, Mike Pitts has proposed a new route for how the bluestones reached Stonehenge. Mike admits that he is guessing, but that these are informed guesses based on the logistics behind moving these megaliths. Mike argues that most of the journey would have followed old Neolithic trails on relatively level ground. You can understand why the transporters would have wanted to avoid as much steep terrain as possible, given the logistical challenges that pushing these stones up significant slopes posed.
Many of these Neolithic trails would have connected villages. Once again, you can imagine the social aspect of the whole journey, with crowds of villagers coming out to watch, support or celebrate the stones’ journey to Stonehenge. Intermittently populated river valleys therefore form a significant part of Mike’s proposed route.
From the Preseli Hills, Mike argues that those transporting the stone first headed down the Taf River Valley, before heading east along the River Tywi. From the Tywi, he argues that the stones were then transported across the Brecon Beacons. The route probably went past where they quarried the Altar Stone from.
This eastward journey continued until the transporters reached the River Usk. From there, they headed downhill until the River reached the Bristol Channel. It is possible that they placed the stones on boats and ferried them down the River Usk, as soon as the river became navigable.
From the mouth of the River Usk, Mike argues that the stones were shipped across the Severn Estuary, before they were transported up various river valleys towards Stonehenge. Notable River valleys here include the Avon and the Wylye.
As for the last, overland part of the journey from the River Avon to Stonehenge itself, a popular theory is that the stones were transported along a prehistoric earthwork called The Avenue. The evidence suggests that this earthwork was built after Stonehenge’s construction, but some believe that its location marked a preceding, long-used Neolithic track. Mike, however, proposes an alternate route following the line of Lake Bottom and Spring Bottom, which approached Stonehenge from the south.
Surrounded by mysteries to this very day, Stonehenge is a site that will continue to captivate audiences across the world and divide scholarly opinion. Some 5,000 years after its construction, Stonehenge’s story is far from over.
Our February Book of the Month
Pitts is a trained archaeologist with firsthand experience digging at Stonehenge. He is also the editor of British Archaeology magazine and author of Digging up Britain, Digging for Richard III, and Hengeworld.
Pitts’ new book is a brilliant introduction to the monument of Stonehenge. He highlights what we know about its construction, what we don’t know and the many theories that abound.