Silbury Hill

Silbury Hill is a 40-metre (130-ft.) high man-made chalk mound near Avebury in the English county of Wiltshire. This is the tallest prehistoric man-made mound in Europe and one of the world's largest. Its purpose however, is still highly debated. Lying low in the Kennet valley in Wiltshire, southern England, the site stands amid the prehistoric sacred landscape surrounding the present day village of Avebury, and contains a complex of Neolithic monuments, including an enormous henge (a roughly circular flat area enclosed by a boundary earthwork), stone circles, stone alignments, and burial chambers. But what was the purpose of such a massive undertaking of organization and manpower? The imposing earthwork structure of Silbury Hill stands at 128 feet high, its flattened top is 98 feet across, and its diameter at the base is 547 feet. The huge 125 foot wide ditch that surrounds Silbury was the source of much material which makes up the mound, an amazing 8,756,880 cubic feet of chalk and soil.

(Image Credit : http://en.wikipedia.org/wiki/File:SilburyHill_gobeirne.jpg)

It has been estimated that construction of the monument would have taken the efforts of 1,500 to 2,000 men working for a year, 300 to 400 men working more than five years, or 60 to 80 men working for more than 25 years. In all, an estimated 4 to 6 million man hours, though some have suggested a figure as high as 18 million hours. Because of its dimensions, Silbury has often been compared with the Great Pyramid in Egypt. According to a radiocarbon date recently obtained from an antler pick fragment, Silbury probably achieved its final form between 2490 B.C. and 2340 B.C.

There is at present no consensus of opinion amongst archaeologists as to how many building phases there were at the huge earthwork at Silbury, though we know its builder used tools of stone, bone, wood, and antler in its construction. The late Richard Atkinson who excavated mound in the late 1960’s, hypothesized three separate phases. In the first of Atkinson’s phases (Silbury I), dated to around 2700 B.C., the earthwork consisted of a low gravel-built mound covered in alternating layers of chalk rubble and turf, around 18 feet high and about 115 feet across. Atkinson believed that Silbury II was begun about 200 years later, and consisted of a much larger mound constructed over the top of Silbury I. In this phase, the earthwork had a diameter at its base of about 246 feet, with a height of 66 feet. Silbury III was the hills final form, basically the earthwork we see today. Atkinson thought that the structure of Silbury III had been built up in tiers of chalk, only the upper two of which are now visible on the monument. Each of these horizontal steps was inclined inwards at an angle of 60 degrees, to provide the monument with stability; the tiers were then filled in with soil, probably from the ditch at the base of the mound.

Despite Atkinson’s three-phase theory, the latest evidence from surveys of parts of Silbury has revealed the possibility of there being only one construction phase at the site. Only a complete survey of the whole monument will decide this issue. There have been three main excavations undertaken at Silbury Hill in an attempt to fathom its mystery. The first of these was carried out by the Duke of Northumberland in 1776, who hired a team of Cornish miners to dig down the top of the mound. However, they found nothing of note, and as the workers did not fill in the shaft properly after investigations were finished, their excavation led ultimately to the partial collapse of the summit of the mound in 2000. Antiquarian Dean Mereweather supervised the excavation of a tunnel from the side of the hill to its core in 1849, but this shed little light on the function of Silbury Hill.

Professor Richard Atkinson’s BBC-sponsored excavations of the enigmatic earthwork, which took place from 1968 to 1970, have been the most comprehensive investigations of the site to date. One of the Atkinson’s three trenches followed Mereweather’s tunnel, but there were no sensational find. In fact, precious few artefacts at all, no burials, and no clues to the function of the structure were found. However, from his work at the site, Atkinson was able to arrive at his theory about how the mound had been constructed. Atkinson’s excavations also revealed considerable environmental evidence, including the presence of flying ants in the turf of the building, which has been used to suggest that construction of the earthwork was begun in the month of August, interpreted by some a coinciding with the Celtic Festival of Lughnasadh or Lammas.

Eventhough Silbury was constructed 2,000 years before, there is evidence of Celtic culture in Britain. Although most archaeologists are at loss to explain the function of Silbury Hill, there has been no shortage of theories put forward in the 300 years of investigations at the site. The belief of the 18th and 19th century investigators was that the earthwork represented the burial mound of an ancient British king. IN fact, local folklore suggests that the hill is the resting place of an unknown King Sil (or Zel), or that it contains a life-size statue of Sil sitting on top of a golden horse.

Another legend tells that the Devil was a bout to empty a huge apron full of soil on the nearby town of Marlborough, but was forced to drop it at Silbury by the magic of the priests of nearby Avebury. Though folklore often contains a grain of truth, no human remains have ever been discovered in excavations at the hill, although it has to be admitted that not all of the structure has been investigated. Other theories about the earthwork include that the flattened top of Silbury functioned as a platform for druid sacrifices, or that the structure was a Temple to Mercury, a giant sundial, an astronomical observatory, a symbolic representation of the Mother Goddess, a power source for passing alien spaceships, or a center for meetings and legal proceedings.

In fact, fairs did once take place on the summit of the Silbury Hill, but that was in the 18th century. One feature of the massive earthwork which seems to point to a ritual function is a possible spiral path climbing up the structure. A new theory (evidence for which was revealed by a 3-dimensional seismic survey undertaken in 2001) goes against Richard Atkinson’s hypothesis of construction in flat layers for the mound, suggesting rather that Atkinson’s steps may actually be a spiralling ledge. This spiral may have served the dual purpose of an access route to the summit during construction and a pathway to the top for ritual processions. This idea would also link with the profusion of the spiral motif in Neolithic art, as seen for example at the temple /tomb at Newgrange in Ireland. That the mound had somekind of religious significance is given credence by its setting within the complex of ritual, funerary, and ceremonial monuments in the area around Avebury; which itself lies only 20 miles north of the roughly contemporary monument at Stonehenge.

The huge ditch surrounding Silbury, probably once intentionally filled with water, may be further evidence of a ritual function. In the early summer of 2001, a huge straight-edged 33 foot wide mark in the vegetation was identified, extending towards the ditch of the Silbury mound. The vegetation or crop mark indicates a deep man-made ditch under the soil, possibly – as some archaeologists believe – built to channel water from local springs into the most at Silbury Hill. Ditches around prehistoric sites, such as henges and hillforts, may not have always been dug for practical purposes, but could also have had a less tangible function, such as a barrier to separate the religious from the malign influences.

The site of the Silbury monument is also interesting. When originally built, Silbury Hill would probably have been a brilliant white structure surrounded by a shimmering moat. However, rather than placing such an awe-inspiring structure on a hill where it could be seen for miles around, its builders placed Silbury in a valley, so it barely protrudes above the horizon, and is hardly visible from the most of the surrounding monuments. Perhaps this indicate that the ground on which the structure was erected was as important as the building itself, though its lowland setting does emphasise its huge size. Intrigungly, Silbury Hill seems to have retained its importance as a sacred site long after it was built.

Excavations at the hill have revealed a large amount of Roman finds, including a ritual platform cutting into the mound, more than 100 Roman coins in the surrounding ditch, and many Roman shafts and wells. On the adjacent Waden Hill, a Roman-British settlements has been discovered, which suggests (along with the finds on Silbury Hill itself) that Silbury was still a sacred site in the Roman period. There are fascinating parallels here with Newgrange, which also retained ritual significance into the Roman period. The Religious attraction of Silbury seems to have continued into the medieval period, as is suggested by finds of pottery, iron nails, an iron spearhead, and a coin of King Ethelred II (dating to A.D. 1010) at the site. The iron nails were found inside small holes that had been dug for wooden posts, at first thought to indicate a defensive structure – perhaps a fort on the hill. However, these post holes were located on the inside of the terraces, which would mean that they served as revetment rather than defense. Further work on the hill will surely reveal more evidence of medieval interest in Silbury.

Unfortunately, the recent history of Silbury Hill has been rather worrying. In 2000, the collapse of the 1776 excavations shaft (due to heavy rainfall) produced a substantial hole in the top of the earthwork. The one positive aspect of this disaster was that it enabled the English Heritage Society to undertake a seismic survey of the mound to probe the extent of the damage caused by the collapse. Fortunately, the ensuing repair work led to further archaeological investigations of the earthwork, which revealed the possible spiral staircase mentioned previously, and the first secure radiocarbon date from the site, the Silbury mound has been off limits to the public.

The meaning of the mound may be inextricably linked with the surrounding landscape, and the other neighboring monuments, such as the West Kennet Long Barrow (a rectangular earthen burial mound) and the Avebury Henge and stone alignments.

Sources :
Hidden History by Brian Houghton;
https://en.wikipedia.org/wiki/Silbury_Hill)