| Summary : Silbury Hill, a large late Neolithic mound. It stands to a height of 31 metres with a diameter of 135-145 metres and comprises over 239,000 cubic metres of chalk. It is surrounded by a wide ditch which extends in the west to form a 'tank' that is often flooded in winter. The mound is situated in close proximity to other significant Neolithic monuments. A series of investigations have taken place since the late 18th century, culminating in the most recent conservation works completed in 2008. In 2000, the centre of the hill collapsed in on itself after falling into a 1776 shaft. Several surveys were undertaken and a conservation project commenced. This included consolidation of the structure and the backfilling of Richard Atkinson's 1968 tunnel with chalk. The new survey suggested the mound was not terraced but may have spiralled down from the top. It was not circular but each level was a polyhedron with a number of straight sides, possibly as many as nine at the base. There were many phases of construction to the mound, and even before the mound was built the site may have been cleared of the natural sarsen stones and deliberately de-turfed for use as a focus for sacred activities. The earliest mound was less than 1 metre high and 10 metres in diameter, and was later enlarged. Further subsequent mounds were followed by a hiatus when only pits were excavated, further mounds were then constructed which were eventually covered in complex layers of chalk and clay resulting from excavation of the surrounding ditch. Silbury became a well-defined bank and ditch enclosure. Radiocarbon dates suggest the mound was built around 2400 BC; the outer layer may have been constructed as late as 2000 BC. A Roman settlement sprung up around the base of the hill, and the hill itself was subsequently modified in the Saxon period. A burial found on the summit is likely to date to around the 11th century AD. Medieval objects and features have also been excavated. |
More information : (SU 10016853) Silbury Hill (NR) (1)
A conical mound with an encircling ditch and a terrace just below the crest of the profile. It stands 130 ft high, is 550ft in diameter at its base, which covers 5 1/2 acres. Excavated on five occasions prior to the latest examination commenced in 1968, under the direction of Professor Atkinson. In 1776 a shaft was sunk from the top centre to the old ground surface. During 1849 a tunnel was driven along the base of the mound to the centre. A cutting on the east side in 1867 yielded antler fragments and, in a disturbed area, a Romano-British iron knife and whetstone. The only recorded excavation in the ditch took place in 1886 (when finds included a coin of Marcus Aurelius), and in 1922 two trenches on the east side revealed further antler fragments. The latest excavations determined that the mound had been constructed in four stages, apparently around a turf stack with a stake circle in the primary mound. No burial or other deposit was found at the centre of the mound but Radio-carbon dating for unburnt vegetable matter from the turf stack gave 2145 plus or minus 95 years. The terrace below the crest of the mound was shown to be an original Neolithic feature, but other minor terraces date from the early 11thc AD. An intrusive burial was unearthed at the top of mound in 1723 while planting trees. The shallow grave contained a decayed skeleton, iron-knife, Viking bridle and deer antlers. (2-6)
OS 1:2500 published survey revised. (7)
The derivation of the name Silbury Hill is uncertain. A solitary 13thc reference describes it as Seleburgh. Its present form was in use in 1663, with a simple alternative of Selbury, a direct derivative of the Selburi hille of c1540. (8)
A few summary accounts of 19th and early 20th century investigations have been published (9-12). During the late 1950s an unsuccessful attempt at locating a burial chamber with a resistivity meter was undertaken (13). Excavations carried out 1968-70 by Professor Atkinson have been summarised in a series of brief interim statements (2-4, 14). He suggests that Silbury Hill was constructed in three main stages, beginning with a primary mound and followed by two subsequent phases of enlargement. Trenches on the summit and on terraces on the side of the hill indicate that it was constructed in a series of dumps of chalk blocks. On the basis of radiocarbon dates, Whittle (15) suggests that Silbury Hill was constructed soon after Avebury, c.3950 bp. Dates obtained so far from Silbury Hill are one from organic matter from the primary mound (4095 +/- 5 bp), plus two from antler found near the base of the final ditch (3849 +/- 43 bp and 3752 +/- 50 bp) (Note: the final report on Atkinson's excavations written up by Alasdair Whittle, is announced as 'forthcoming' in the bibliography of Whittle (15)). A summary of work at Silbury Hill has been published in Malone (16). Ucko et al (17) discuss antiquarian investigations in the Avebury area, including Silbury Hill (17). (9-17)
Atkinson's excavations were published in full in 1997 by Whittle, the report containing also a summary of earlier work at the site. Excavation has occurred on several occasions, beginning with the digging of a shaft from the top in 1776-7, and including an attempt to dig a horizontal tunnel to the centre in 1849. The most recent excavations were conducted 1968-70 by R Atkinson, which utilized the 1849 tunnel. The monument was shown to have started as a mound circa 40 metres in diameter constructed on a chalk spur projecting onto the Kennet valley. There was no clear evidence for any major pauses in the construction sequence, and the mound was subsequently enlarged to a diameter of circa 160 metres by piling up chalk rubble in horizontal layers. Chalk was obtained by digging a surrounding ditch, which had the effect of cutting back the chalk spur and exaggerating the apparent height of the constructed mound. Limited excavation on the top of the mound revealed concentric chalk walling, suggesting that the mound may have been constructed as a stepped cone. It is unclear whether the flat top is an original feature or the result of later modification. Dating evidence is problematic, but Whittle suggests that construction probably occurred during the mid-to-late 3rd millennium BC. The summit has seen several later episodes of disturbance, including some form of revetment of late Saxon date (late Saxon or early Norman potsherds were found, as was a coin of circa 1010AD). William Stukeley recorded the discovery of a skeleton in 1723 during tree planting on the summit. The finds suggest that this may have been of similar date. Roman finds have been reported from some of the excavations, and a "midden" layer was found in the upper fill of the quarry ditch during Atkinson's excavations. Silbury Hill is a scheduled ancient monument. (18)
Survey revealed that in plan the form of the mound is dictated by a series of radial spines or spokes from which straight sections emanate in a similar manner to a spider's web. The summit of the mound is sub square rather than circular and the base possibly octagonal. The model of tiered construction as proposed by Atkinson may need to be modified as is if perambulated, the uppermost visible ledge returns to a point below the start and the 'terracing' could therefore be part of a spiral arrangement. A ramp leads from the penultimate ledge to the summit and while this could have been an original feature it could equally have been of late construction. A number of deliberately constructed platforms occur around the lower slopes. These cut into the original profile of the mound and therefore post-date its construction. Collapse of the excavation tunnel dug by Merewhether and reinvestigated by Atkinson can be detected on the surface. Earthworks on the summit include a tree planting ring around the lip and a possible remnant of the spoilheap associated with the 1776 shaft.
The old ground surface is visible as a break of slope for much of the circumference of the mound while remnants of chalk representing the old ground surface exist to the north and east of the ditch.
The presence of significant quantities of pottery and other artefacts from the site generally and medieval pottery in Atkinson's trenches on the upper leadges indicate significant Roman and Medieval episodes (19).
Silbury Hill is a large late Neolithic mound that stands to a height of nearly 40 metres with a diameter of about 168 metres, which is surrounded by a ditch. It is situated on the western side of the Kennet valley in close proximity to other monuments (see associated records) that were clearly of great significance in the Neolithic period. A series of excavations and investigations have occurred at the hill including work by the Duke of Northumberland in 1776-77; J. Merewether in 1849; J. Fergusson in 1867; A.C. Pass in 1886; W. M. F. Petrie in 1922; and R. J. C. Atkinson from 1968 to 1970. These include a series of tunnels and shafts dug into the side or top of the hill in an attempt to reveal its mysteries. Atkinson proposed that the hill was built in 3 phases; the first stage being a turf mound, which was covered by a chalk mound and in turn enlarged to form the present day mound. He claimed that it was built in tiers resembling a stepped conical pyramid. On May 29th 2000, the centre of the hill collapsed in on itself after falling into a shaft of 1776. Several surveys were subsequently undertaken by English Heritage and a project began to conserve the hill. This included a major effort to consolidate the structure and back-fill Atkinson's tunnel with chalk in 2007. This work showed that there were originally many phases of construction to the mound. Analysis also showed that some of the turf forming the hill had been trampled and mixed with chalk. Survey work suggested that the mound was not terraced but may have in-fact spiralled down from the top. Furthermore it was not circular but each level was a polyhedron with a number of straight sides - possibly as many as nine at the base. The turf at the centre was extremely well preserved and is believed to have been constructed within a century of 2400 BC. The outer layer may have been constructed as late as 2000 BC. The hill is believed to have had a range of later uses including significance to a nearby Roman settlement, the location of a Christian building as well as being home to a late Saxon or Norman military structure. (18-23)
In 2008, two letters were found in the British Library, written by Edward Drax to George Pitt (Lord Rivers) while he led the work on Silbury Hill in 1776. They describe the excavations, and support the theory that the early phases of the mound had perhaps been piled against a central post (since rotted away). Illustrations held in the Bodleian Library, Oxford, depict the mound after these investigations in 1788.
A history of the antiquarian and archaeological investigations is also presented in the 2010 English Heritage book, along with the results of the 2000-2007 conservation and survey work. The book also considers the purpose and meaning of the mound, past and present. (24) |