Aubrey Burl on the Boles Barrow mystery

British Archaeology
no 45, June 1999

ESSAY
Glaciers and the bluestones of Wales
It was not human effort that brought them to Stonehenge, argues Aubrey Burl

Ever since the source of the Stonehenge bluestones was identified as the Preseli ridge in Pembrokeshire, it has been accepted that they could only have reached Salisbury Plain by human effort. Despite cogent arguments favouring glaciation, the majority of geologists have been firm that this was impossible, even though erratics from West Wales have been identified two-thirds of the way from the Preselis to Salisbury Plain at a site near Cardiff, and also on Flatholme and Steep Holme islands in the Bristol Channel less than 60 miles west of Stonehenge. Archaeologists have been even firmer in their belief in an almost superhuman feat of men transferring some 80 heavy slabs a distance of over 200 miles.
Data from standing stones, circles and tombs reveal that prehistoric societies did not fetch massive blocks from any great distance. Where there was convenient stone they used stone. Where there was not they used timber or earth.
There has been little serious consideration of the logistics involved in the hypothetical journey from Wales to Wiltshire. The most meticulous was by Richard Atkinson. In his scheme, the stones were brought by land and river to Milford Haven, floated along the shores of South Wales and up the Severn, and then taken by rivers and land-portage up to Stonehenge. He suggested the use of a pine raft with a crew of twelve. A modification of his description would envisage a tree-trunk platform about 6m square, constructed for buoyancy in three layers, each of 20 logs 6m long and 0.3m thick. With a dry weight of 35lb per 0.03m3 the logs would have weighed about 20 tons and the entire cargo of wood, stone and men over 30 tons. Whether this unwieldy craft was seaworthy and capable of being manoeuvred during the day and beached night after night by a small crew is doubtful.
On a floating platform without sails, with propulsion dependent on paddles and poles, with little control over steering, affected by every capricious current of the Atlantic Ocean and Bristol Channel, the kamikaze crews faced daunting challenges. Once out of the shelter of Milford Haven, almost immediately the voyagers would have encountered strong tides and under-tows across the dangerous waters surging southwards near Freshwater West. Tidal flows of three to five knots streamed on the east side of Carmarthen Bay, and beyond them were treacherous sandbanks at Cafn Sidon Sands. Between Carmarthen and Swansea Bays heavy currents swirled at every headland. A mile from the coast off Ogmore-by-Sea lay the reef of Tusker Rock on which many mechanicallypowered ships later foundered.
Even when the mouth of the Severn was reached the struggle was not done. The river could pour seawards at up to ten knots, there were submerged mudbanks, the highest rise and fall of tides anywhere in the British Isles, all this before the Bristol Avon was reached at Portishead. At that point the stone would have to be transferred to something more suitable for travel along narrow and winding rivers. Further miles against the current took the vessel to Frome where everything again had to be disembarked for a portage that required a work-gang to drag the stone some eight or nine miles over land rising persistently to Warminster. There the cargo was replaced in the reassembled craft for another up-river crawl to West Amesbury, and once again unloaded and hauled up the chalk slopes to Stonehenge. This unprecedented undertaking had to be repeated almost 80 times.
The truth is, rather, that no such undertaking was necessary. The most compelling evidence for glacial transport of the bluestones is that at least one substantial block was on Salisbury Plain centuries before the construction of Stonehenge. It lay in the Neolithic Boles Barrow which had been blocked up and abandoned long before the bluestone circle was erected. Following his excavation of Boles Barrow of 1801, William Cunnington wrote of the barrow's `large stones' amongst which he discovered a `Blue hard stone ye same as the upright Stones in ye inner circle at Stonehenge'. For his period, Cunnington was a competent geologist, well able to distinguish between sarsen and dolerite. He removed ten stones from the barrow and arranged them in a circle in his garden at Heytesbury. After his death, a bluestone was taken from his garden to Heytesbury House. From there, it was given to the Salisbury and South Wiltshire Museum by Siegfried Sassoon in 1934.
It has been argued that the bluestone in the Salisbury Museum came from Stonehenge, not from Boles Barrow. This, however, is contradicted by a statement of Flinders Petrie, later the famous Egyptologist, who in 1877 made a punctilious survey of Stonehenge. As a result, he was able to assert `entirely confidently' that `No stones are missing since Wood's plan'. John Wood had made the first really accurate plan of Stonehenge in 1740, distinguishing between stones that were erect, leaning, flat, buried, and lying on the surface of other stones. He is unlikely to have left a largish bluestone unplanned, especially as he had plotted stone 32 at the east of the bluestone circle, a stump no bigger than Cunnington's. Scrutiny of the two plans shows that Petrie was right. No stone is missing. As Cunnington found his stone in 1801 it cannot have come from Stonehenge. The evidence is clear-cut. It does not support belief in human transportation of the bluestones from south-west Wales.

Dr Aubrey Burl is an expert on stone circles and a former sailor. This is an edited extract from his book, Great Stone Circles, recently published by Yale (£19.99) 

See also:  Cunnington, B H, 1924, The Blue Stone from BolesBarrow, Wiltshire Archaeological and Natural History Magazine, 442, 431-47