Issue 116

Jan / Feb 2011

Contents

news

All the latest archaeology news from around the country

features

Crosby Garrett Roman Helmet

The fullest report yet on its discovery, appearance and modern fate, plus its restoration

THE BIG DIG: Flixbrough

20 years of study at the Lincolnshire DMV

Fieldwalking in Bingham

The community story of a Nottinghamshire parish

Silbury Hill

What is it and how was it made?

The Varmints Show

In the Varmints' fourth exploration of music and archaeology, we look at Music and Place

on the web

Military sites of all periods and online teaching of GIS

CBA Correspondent

Our Casework team reviews another year of listed building saves

letters

Your views and responses

ISSN 1357-4442

Editor Mike Pitts

feature

Making sense of Silbury

English Heritage has nearly completed a major study of Silbury Hill, Wiltshire, as part of a restoration project that followed collapse of old excavations in 2000. Jim Leary, who directed excavations, and David Field, who surveyed the monument, describe the new story that has emerged, and how this changes the way we think about this huge mound.

Silbury Hill is clear evidence that a chief organised a large labour force. On the contrary, it was built by the people, but its flat top became a stage for a new elite seeking power. It was a platform from which to view the horizon, or to play music. Its height brought people closer to the sky. Its pregnant bulk honoured female fertility. "Absolute nonsense", said Glyn Daniel, the 20th century archaeologist who took a special interest in prehistoric tombs. "I think it's the biggest round barrow in existence, and there's no more to it than that."

There has been no shortage of opinions on why Silbury Hill was built over 4,000 years ago. Perhaps the commonest theory is simply that we will never know: Silbury, the largest artificial prehistoric mound in north-west Europe, is an eternal mystery.

What all such ideas have in common is that they take the hill, as we see it now, as the start and end of the story. When 40 years ago Richard Atkinson defined the construction phases still commonly quoted, he envisaged a rapid succession of three ever-larger Silburys, as if the earlier mounds were mere stages on the inevitable route to terminal monumentality.

Our new work at Silbury, appropriately, perhaps, designed to clear up the legacy of an unstable mound left by earlier generations of archaeologists, causes us to rethink all this. Trivially, Silbury's flat top may be a bit of a red herring, and not part of its ancient shape: it seems to have been altered in later periods. More fundamentally, many interpretations are undermined by what we now know of the site's early history and its subsequent development. People who dumped gravel on the ground at the beginning cannot possibly have known what would be there at the end, or the phases the mound that developed would go through – or that it would take several generations to complete. They could not have imagined what could be seen from a summit that had not been conceived.

Between May 2007 and May 2008, the opportunity was taken to examine and record in detail all that was accessible from the tunnel that had been sealed in 1969. As is well known, this ran near its base from the southern side of the hill into the centre, providing a continuous section no higher than a person (a very small opening in the context of the total mound). In the tunnel, the buried ditch was excavated, and on the summit it was possible to investigate some of the most recent structural evidence. The significance of all this is that when the tunnel and the top of the mound were first explored by archaeologists in 1968–70, they did not record anything like the detail we were able to, and many of the original records are lost. We came away with a totally new understanding of Silbury Hill.

No blueprint

The first signs of activity at the site apparently have nothing to do with construction at all, but consist of charred plant remains (including hazelnut shells), a couple of pig teeth and debris from flint knapping. We can then see the ground being prepared for a gravel mound 10m across and barely a metre high. This was then enlarged with layers of topsoil, subsoil and turf (which we call the lower organic mound) within a ring of wooden stakes, and surrounded by smaller mounds. Pits were dug into the top of the central mound, before the whole complex became covered by a larger, upper organic mound that contained small natural sarsen stones. By now the mound was 5 or 6m high, and around 35m across.

A massive ditch – over 6.5m deep – then gave the site an entirely different character. It probably formed a circuit 100m across, with an internal bank that enclosed all the earlier activity (see drawing above). However, it may well be that there had been an enclosing ditch from the start; the diameter of this ditch is comparable to those at Stonehenge and the Flagstones enclosure, Dorset, which date from 3000BC or before. Not even this was straightforward, though; the unweathered ditch sides show that it had been rapidly backfilled and then repeatedly recut, each event apparently slightly widening the circuit.

Once again the mound was enlarged. This was not a single construction, but an incremental growth, with a series of ring doughnut-like chalk banks being added to the outside. The ditch was backfilled and another dug beyond it, leaving space for the mound to be enlarged yet again.

The lower organic mound rose around 2450–2400BC, with the upper organic mound completed soon after this. The chalk mound above these reached its highest point about a century later. Silbury, in other words, was far from a single construction project, but the site of an array of activities that may well have taken quite different forms.

Archaeologists, focusing on calculations of cost and labour input, have often considered Silbury as if it were a modern construction site, where work is simply a necessary process to get something built – as if the builders had some sort of blueprint, bypassing the drama and excitement of the monument's history and consequently the real point that lay behind it. But one thing is certain: those who constructed Silbury would have had a different set of beliefs and values. Round mounds appear all over the world, from Britain and Europe, to Asia, Australia and the Americas, and are remarkably persistent across many different eras. There will of course be different emphases and interpretations from place to place. But let us consider just one example, the Hopewellian mounds in the eastern United States.

Made of myths

The Hopewellian mounds of the middle Woodland period (approximately 50BC–AD400) provide an excellent case to study. Some of these mounds were on depressions known as ritual basins, although most covered wooden structures that might or might not contain burials. Structures were dismantled or burnt and then midden debris (domestic rubbish), earth and other materials were ceremonially added to form the mound.

These monuments are prehistoric, but recorded Native American myths and beliefs may help us to understand the archaeology. For example, the use of black mud and clay in the centre of many of these mounds could symbolise ideas about how the earth was formed. A common myth relates that an animal – anything from a muskrat to a duck, depending on the region – plunged to the bottom of the primordial sea and brought up some mud, which grew to create land. The black, waterlogged mud in Hopewellian mounds may have been a re-enactment of the Earth Diver myth, the audience participating in the story by building the mound: creating it was to create the world. Variations on this theme can be found throughout Europe, Russia, Mongolia, Egypt and across Asia. In the latter, a boar retrieved a lump of mud, that became land, on the end of its snout.

Of course, this has nothing to do with the British neolithic, and there are many different beliefs that could support one view or another. But the Hopewellian case underlines the fact that our prehistoric beliefs are likely to have been far more complex than we might think. The key point is that the actual process of construction was as important as the final form – perhaps more so. The soils in the mound were designed to be read and understood in relation to myths. The final form was a by-product of re-enactment, left standing as a reminder of – a memorial to – the myth. Perhaps Silbury too was "authored": the soils were imbued with symbolism, and placed in an ordered fashion to be read and understood as they were being laid down.

Soils can have symbolism today. When the old Wembley Stadium was demolished in 2002, the rubble and soil were piled up in four huge mounds just outside London – latter-day Silburys sanctified by decades of iconic sporting events and rock concerts. We can also see the significance of soils and rocks in the megalithic monuments of western Europe, where shape, colour and texture mattered. At our own Stonehenge we seem to have an extreme example, where stone for the megaliths was brought to the site from huge distances.

So at Silbury Hill. Mound material appears to have been thoughtfully selected, each organic phase linked to a particular geological location. Soil in one of the mini-mounds seems to have come from a woodland setting, unlike soil from the main mound, which had a grassland origin. These dark organic mounds contrast starkly with the underlying yellow gravels in the first mound, as well as the overlying chalk. Sarsen boulders were deliberately incorporated into at least two of the phases; not standing on top or around the base, but unseen in the body of the mound. Heavy sarsen boulders had been lugged to the summit to add to the chalk walls. Antler picks and fragments seem too to have been deliberately incorporated.

Perhaps different communities brought a basket-load of earth from their home grounds, creating an enduring link with the site – claiming or reaffirming rights to live in the area or renewing mythic connections that bound them to the land. Taking part may have brought good luck or health. Or perhaps like the American Hopewellian mounds, Silbury was made of myths – acts from a different world made permanent on this one. The hill embodied decades of public performances.

Silbury is not just a mound. There is also a ditch, dug into the lower slope of the hillside and expanded to form a rectangular area alongside. The excavation must have been an enormous affair: there was no need to dig so deep if only to provide chalk for a mound, as it would have been easier just to quarry the hillside. The ditch and its extension seem to have retained water; military terminology might describe it as a moat. And ditches too carry additional significance in other parts of the world. They could impede malevolent spirits.

The mound rises

Silbury Hill grew gradually, in a piecemeal fashion. However, at some stage this process must have resolved into an ever more formal construction, perhaps with the original meanings and purposes lost. As the mound swelled to proportions that posed serious safety risks, revetment and greater solidity must have been needed, witnessed by the chalk rubble walls present in at least the outer casing. When this change occurred is unknown, since we have been unable to investigate the greater part of the hill.

Did Silbury ever reach a "final mound", perhaps with a grand unveiling of the monument? Or did it just stop being added to as ceremonies and beliefs changed? We cannot know. It is unlikely, however, to have gleamed white for long. Plant colonisation would have started within a few years of fresh chalk being added. The experimental chalk mound constructed nearby on Overton Down in 1960 showed that within the first 20-odd years, a mosaic of broken patchy vegetation cover had formed on the sides, with smaller bare areas on the top. Of course, Silbury could have been deliberately weeded: but equally it may have been carefully scattered with soil and seeds.

Once established, it continued to be used and adapted. From the top one would have had a clear view into the contemporary palisaded enclosures at West Kennet and parts of the Avebury henge. Its size and location in a natural bowl gave it good acoustic properties, perhaps later exploited to add otherworldly aspects to the experience of ritual. In 2007 English Heritage archaeologist Sarah May asked musicians to play instruments from the summit, such as whistles, drums, flutes and horns, and volunteers recorded what they could hear. Digital modelling showed sound transmission was particularly good to the south, towards the Swallowhead spring, but less obvious to the north and Avebury.

The later stage of Silbury Hill reached a massive 31m high, unmatched anywhere else in Britain. Even in north America, only Monk's Mound at Cahokia, Illinois, formed of four terraces and rising about 30m, approaches this height (though with a base of 305mx236m it is of greater bulk). In Europe, monumental mounds occur in Brittany, particularly around Carnac where the massive prehistoric tumulus of Saint-Michel rises up 12m and, like La Hougue Bie, has a chapel on the summit. These invariably cover earlier features and are formed in stages.

The massive 16m high mound of Krakus looms large over the city of Krakow in Poland. Thought to date to the 10th century AD and half the size of Silbury, it was excavated in the 1930s. It was constructed around a central post with seven radial fence lines separating nine different segmented deposits. It is worth recalling Silbury's straight sides (see feature, Jan/Feb 2005), and whether they might represent similar construction elements. In the United States there is a series of spoked monuments without covering mounds. At one of the best known, the Medicine Wheel at Bighorn, Wyoming, 28 spokes perhaps represent the lunar cycle, whose symbolism is retained in the rafters of ceremonial lodges. In India the Chakra is emblazoned on the national flag, a 24-spoke spinning wheel version of the ancient eight-spoke chariot or Dharma wheel representing perfection, with each spoke a virtue such as kindness, justice and love.

Around the world there are beliefs that the circle represents the passage of human life, the cycle of the year, month and day, of the sun and moon and of the cosmos; or in the natural world, of ripples in water, or the shape of nests and beaver lodges. A circle has no end. To some Native Americans it symbolises life. The enormous spiritual complex known as the Temple of Heaven in Beijing reflects the ancient Chinese belief that heaven is round and the earth is square. Sacrificial activities took place at the winter and summer solstices, asking for rain or a good harvest.

No simple analogy is going to explain Silbury. But like the complex history of construction and growth now revealed by excavation, the variety of beliefs and rituals around the world at what might seem straightforward monuments reminds us that, in human affairs, nothing is as down-to-earth as it looks.

Jim Leary directed excavations at Silbury June 2007–08, and David Field surveyed the mound and its surroundings and researched their history, both working for English Heritage. Their book, The Story of Silbury Hill, is reviewed in the printed issue.

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