In 1663, the writer John Aubrey was showing Charles II the Avebury henge, when his Majesty “..cast his eye on Silbury-hill about a mile off; which they had the curiosity to see.”
He was told that, according to local tradition, King Sil, was buried there on horseback, and that ”..the hill was raysed while a posset of milke was seething.”
In the way of all good traditions, the story King Sil grew over the centuries and the posset or bowl of milk somehow became a golden horse.
The history of the many archaeological excavations at Silbury is an interesting story in its own right, and we will turn to it shortly, including the work done by English Heritage between 2007 and 8 which has been particularly insightful and has overthrown many previous theories and speculations.
But first a little about the hill itself.
The mound was built in three main stages between around 2450 and 2400 BC, meaning it was probably built at the same time Stonehenge and Durrington Walls just a few miles away. Silbury Hill is 41m high (130ft) and has a base circumference of 494m (1630ft). It was contemporary with Egypt’s pyramids (141m).
Silbury is unique only in scale, there are two similar but smaller mounds nearby, one of which – SilBaby – is just a few fields away, the other is in the grounds of Marlborough College and was believed to be considerably younger until very recently.
Now, let us return to the excavation history.
The Drax shaft, 1776
In 1776 the Duke of Northumberland asked Colonel Drax to tunnel into the mound. He brought in tin miners from Cornwall and sank a vertical shaft in the hope of finding the burial chamber, the golden horse and various unnamed treasures. All they found was a thin slip of oak. And they even burnt one end of it with a wax taper and discovered it was wood and not the whalebone they thought. Later excavations found that because the hill is not precisely circular, he missed the centre anyway!
The Merewether tunnels, 1849
Much had been learnt about tunnelling techniques by the time John Merewether, Dean of Hereford, employed navvies and drove a 300ft horizontal tunnel from the south-western edge to the centre of the mound. The excavation was arranged with the support of the Archaeological Institute, which requested that men dug “night and day” so that completion could co-inside with their Salisbury meeting. The tunnel was to be six and a half feet high and three feet wide – for the sound archaeological reason that it enabled the visitors to walk in without removing their top hats! Digging the last few feet was paused so that the Institute members would be there at the very moment of discovery.
Sadly nothing was discovered, no golden treasure, no grave goods, just a traceable line from the original turf. To be fair a hollow-sounding place had been detected in the roof of the tunnel, but after extra excavation the sound disappeared and was never heard again.
Undeterred, the Dean ordered side passages to be dug near the centre, and in one of these they found …….. the in-filling of the base of Northumberland’s shaft! His pattern of tunnels was continued until it came to resemble, in plan, the shape of an elaborate pastoral staff.
Flinders Petrie excavates, 1922
Professor Flinders Petrie’s work on the pyramids made him look for an entrance into the burial chamber on the mound’s surface, probably via a sloping tunnel. He first looked at the south-eastern, and then at the southern perimeter of the mound but found no entrance and reasoned that if there was one the excavation, would prove to be too expensive to ever uncover it. He felt that if such a passage existed it would be in the style of the local long barrows with sarson stones used for the walls and ceiling.
Dr McKim’s survey, 1959
Dr McKim carried out a resistivity survey of the hill as this would reveal if there was a passage entrance. He found a single well-defined irregularity. And indeed it was the entrance to a tunnel – the metal door covering Dean Merewether’s tunnel to be precise.
Dr McKim also found a faint overall oscillation in readings which he interpreted, probably correctly, as the original pattern of dumping chalk materials.
Professor R. J. C. Atkinson and BBC 2, 1967
In 1967, Professor Richard Atkinson and BBC 2 undertook what was billed as “One of the most exciting researches ever undertaken in British archaeology” and “Viewers will see everything of significance as it happens. If a particularly interesting situation develops there may even be five-minute programmes every day.” Yet other publicity proclaimed “Some archaeologists believe that it is the largest of all Bronze Age barrows and is likely to contain a royal burial of exceptional richness.”
The programmes began 8th April 1968 and continued until 9 August 1969. On the very last day the first man-made container ever to have been discovered under Silbury Hill was found. It was a tall, sealed, cylindrical pot, found embedded in the very heart of the hill. Although cracked it was soon taped together and under the full glare of the cameras, the well preserved mementoes of the 1849 excavation were revealed.
English Heritage 2007-8
In 2000 a sixty foot hole appeared in the top of Silbury Hill, brought on by collapse caused by previous excavations. As part of preparing a preservation plan English Heritage carried out extensive work on the hill.
The first activity found at the site has nothing to do with its construction at all, but consisted of charred plant remains (including hazelnut shells), two pig teeth and debris from flint knapping. Above that there are signs that the ground was prepared for a gravel mound 10m across but just one metre high. This was then enlarged into a lower organic mound which had a ring of wooden stakes around it, it was surrounded by smaller mounds. Pits were dug into the mound, which was subsequently covered to a height of 5 or 6m (35m across) with an organic layer that contained small natural sarsen stones.
Silbury was finished about a century later and was far from a single construction project, but seems to have been the site of an unconnected series of activities, that do not follow any obvious common plan.
As a result of the 1967 excavation, it was believed that the mound was constructed as a layer cake with a series of round flat platforms built one on top of the other, each with a radiating set of retaining walls. However, it now seems that a spiral construction technique was used.
In many ways the most mysterious features of Silbury don’t even relate to the mound itself, but to the gargantuan ditches that were excavated through solid bedrock (and would have provided far more rock than could be used in the hill. They formed a circuit 100m across and 6.5m deep – but almost as soon they were was dug they were reburied (before there were any signs of erosion). Even more unexpectedly they were repeatedly re-cut, each event widening them slightly.
Silbury’s enigmatic shape, with its flat top (originally thought to be for ceremonies) may not be original or even relevant. The flat top probably came much later as a series of medieval post-holes on top of the hill indicate a large building. The discovery of two arrowheads imply it was defensive and built either at the time of the Danish invasions early the 11th century, or the Norman Conquest. There is speculation that a dome-shaped prehistoric summit was simply altered at this time.
But why was Silbury built at all? Answers have ranged from a kingly burial mound to Druids (even though it was built 2,000 years too early for that), to a Neolithic cathedral, a mother goddess shrine (as from the air the shape of the ditch was said to resemble a pregnant woman – though to me it looks more like a guitar case) and even by space aliens with their corn circles.
Many say it must have been related to the local and ancient “ritual” landscape with its numerous round barrows, long barrows, smaller hills, Avebury, Stone Henge, Marden Henge, Durrington Walls and far too many others to list here. Despite all of the work, geophysics, excavations, interpretations, brainpower and erudite comments, we will probably never know.
By Gerry Palmer