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 Silbury Hill news, views and archive brought to you by Weird Wiltshire Introduction Latest News News Archive Excavations The Hole Beaker People What is it for? What Next? Postcards Wallpaper Links  |
Thursday 1st Dec 2005 Bid to save Silbury Hill could cost £600,000 THE collapse of infill at Silbury Hill has happened before and will happen again unless urgent action is taken to stabilise it, a meeting in Devizes heard on Saturday. English Heritage had called the ticket-only meeting to discuss its preferred option for the future of Silbury Hill, the most ancient man-made structure in northern Europe. It wants to enter the tunnel dug by a team of archaeologists in 1968 and back-fill it with chalk, also filling in the voids created during the various excavations of the mound since the 1776 tomb-raiding exploits of the Duke of Northumberland. Amanda Chadburn, one of the English Heritage team who has been investigating the current state of the hill, said the appearance of the hole at the top of the mound in May 2000 had come as a shock to archaeologists. There had been a further collapse in December 2000 after which the hole was given a metal cap supported by scaffolding. The hole is now temporarily filled with enormous expanded polystyrene blocks. It had been well known that the Duke of Northumberland, searching for the legendary golden statue of King Zil reputed to be buried in the mound, had employed miners to dig a shaft straight down through the centre of the hill and had refilled it with branches topped with a chalk plug. The situation was made worse by a subsequent tunnel dug into the side of the hill by workmen hired by Dean Merewether in 1849. But during her investigations through the archives of various museums in the county, Ms Chadburn had discovered that the collapse of the central shaft had happened before. She showed an aerial photograph taken in 1925 clearly showing a hole at the top of Silbury Hill, similar to the one that opened up in 2000. She had also found letters referring to this hole that was eventually filled in by the Ministry of Works in 1936. Archaeologist Fachtna McAvoy said boreholes were driven into the hill by English Heritage to carry out a seismic survey of its interior. Cameras were lowered down these holes and archaeologists were appalled to see huge voids that had appeared in the 1968 Atkinson tunnel that was supposed to have been properly backfilled. Bob Bewley, regional director of English Heritage, said it was important to enter the tunnels and make sure that all voids were properly filled to prevent any further collapses within the ancient monument. But Nigel Swift, for the protest group Heritage Action, urged English Heritage to think again. He told the meeting: "Re-tunnelling will destroy a lot of archaeology so we would have to have a lot of confidence that English Heritage knows what it is doing. We see no confidence in it." He said English Heritage's own figures showed the damage caused by tunnelling would amount to 166 cubic metres and a better option would be grouting the voids from outside the hill by pumping in filler material. Professor Chandler from Imperial College, London, said the hill was in no immediate danger. He said: "The hill looks not too different from the way it looked when it was completed. Rabbits and badgers are doing more damage than anything else done to it over the centuries." Mr Bewley said that invitations to tender were going out to prospective contractors over the next few weeks and the work was unlikely to be complete before 2007. The cost has not been finalised but it is thought to be in the region of £600,000. Thursday 10th Nov 2005 Final solution to save Silbury from disaster THOUSANDS of tourists who have viewed Silbury Hill over the last four and a half years, have probably been unaware of the crisis over its long term stability. From the ground the huge grass mound looks much the same as it has in recent centuries. But the hill is now desperately fragile and, like a giant Gruyere cheese, it is full of excavation tunnels and shafts that experts fear could collapse. English Heritage now wants to discuss some of the conservation options that have been put forward over the last five years. The purpose of the meeting on November 26 is to consult on preferred options for conserving the monument, which forms part of the Avebury World Heritage Site. A spokesman said it was proposed that the final option chosen would also allow further investigation to find out more about the hill and its origins. He said: "The option chosen is to re-enter Silbury Hill via the tunnel dig to its centre in 1968, and then remove the existing collapse and inadequate backfill in the tunnel before properly filling it in. "The tunnel and other voids within the hill would be filled with chalk to the same density as the surrounding mound material. "The work of backfilling would take place backwards from the centre of the hill and enable contractors to remove any temporary supports left after previous excavations." He said the work would be accompanied by a thorough archaeological investigation to record all parts of the hill as they were exposed and to help learn more about how the hill was built. He said monitors would be installed to keep a check on how the new chalk infill was settling in. "The benefit of this way forward is that it will return the hill to as near its original state as can be practicably achieved," he added. Before the work can go ahead English Heritage is planning a full consultation with all interested groups ranging from architects and historians to local people. Admission to the meeting at 11am on November 26 in Devizes Corn Exchange, will be by ticket only. Applications to Beverley Ballon on 0117 975 0703. In May 2000 it was revealed that a 225-year-old vertical shaft dug by treasure seekers in 1776 had started to collapse. It is likely the miners who were paid to fill in the 130-feet deep shaft simply poked branches in a few feet down from the top to support an earth plug. Five years ago the plug gave way, opening up the shaft and exposing a hole eight feet square. Within days the shaft funnelling and the sides of the hill collapsed inwards. English Heritage responded by intitially placing a temporary canopy over the hole then temporarily plugging with polystyrene topped with soil. Civil engineers Cementation Skanska carried out a seismic survey and revealed a series of unfilled tunnels and collapsed excavations. Since 2001 the hill has remained packed with polystyrene awaiting a long term solution. Invitations have been sent out this week to archaeologists and other interested parties to ask them to the meeting to discuss how the enigmatic Neolithic monument should finally be stabilised. Thursday 11th Aug 2005 The £600,000 plan to shore up Silbury Hill EXPERTS have come up with a plan to save ancient landmark Silbury Hill from collapsing in on itself but they need up to £600,000 to carry it out. English Heritage has reached a decision on which option to take to stabilise the ancient monument, the largest prehistoric man-made construction in Europe, and guarantee its continued existence for centuries to come. It has chosen to re-enter Silbury Hill through the tunnel dug to its centre in 1968, the subject of a BBC film made by Magnus Magnusson at the time. The existing material that has been used to backfill the various excavations that have taken place over the last 200 years or so will be removed and replaced with chalk to the same density as the surrounding mound material. The temporary capping at the top of the shaft dug into the hill in the 18th century, which is composed of expanded polystyrene, will be removed and it, too, replaced with chalk. Bob Bewley, south west regional director for English Heritage, said: "The tunnels have never presented the major problem. Most of the subsidence is as a result of the shaft that was dug by the Duke of Northumberland's men in 1776 straight down through the centre of the monument in the search for gold. "They found no gold at the base but it has left us with major headaches as it has never been satisfactorily filled in and is the cause of all the major subsidence that has threatened Silbury Hill." Mr Bewley and his colleagues are confident that recent work to stabilise the monument will keep it safe in the short term while arrangements are made to undertake the massive effort to complete the repairs. It has already been five years since a massive hole opened up at the top of Silbury Hill, which was exclusively reported by the Gazette at the time. But Mr Bewley explained that rescuing a 4,700-year-old construction from dereliction is no short-term matter. He said: "We have not taken the quick and easy fix but have tried to understand what is happening inside the hill, which is why is has taken so long to come up with our decision. "When we are finished the hill will hopefully not require any further attentions for hundreds of years, although we will be monitoring it regularly." A project board meeting is due to be held in October when a decision will be taken to put the work out to tender. Mr Bewley said: "We hope to find the right contractor in this financial year and the work will be started in either the next financial year or the following one. "The biggest thing will be finding the money for the work. We reckon it is going to cost in the region of £500,000 or £600,000 and we are going to have to find that money from somewhere. "Some of that may come from commercial sponsorship. Large companies and other organisations may be pleased to be involved with this kind of project. "It is a World Heritage Site and will attract publicity from all over the world." Thursday 23rd Dec 2004 Threat to the hill SILBURY Hill is at risk of an internal collapse, says leading Wiltshire archaeologist Mike Pitts, unless urgent remedial work is carried out on an exploratory tunnel. The tunnel into the south west slope of the 5,000 year old hill claimed to be the largest man-made mound in Europe was dug in 1969 by a team led by Professor Richard Atkinson from Cardiff University. The dig was filmed by the BBC whose reporter at Silbury Hill for the Chronicle series was Magnus Magnusson, later the Mastermind host. Mr Pitts, of Marlborough, the only living archaeologist to have directed excavations at both Avebury and Stonehenge, told the Gazette that a survey has shown a gaping cavity where Atkinson's shaft was backfilled. He said that unless the hole is filled or shored-up it could lead to a further collapse. The Gazette was the first to reveal in 2000 that a 225-year-old vertical shaft at the core of the hill had collapsed, leaving a hole on the summit. That revelation led to a major survey of the hill by English Heritage, which manages it on behalf of its absentee owner Lord Avebury. English Heritage employed specialist Swedish civil engineers Cementation Skanska to drill survey boreholes from the top of the hill to the bottom to see if any further voids could be found. A camera lowered into one of those bore holes revealed that the Atkinson tunnel backfill had been inadequate, said Mr Pitts. After studying some of the pictures sent back from the bottom of the bore hole Mr Pitts said large voids can be seen in the Atkinson tunnel. He said: "The whole hill appears to be stable, which is good news. "The bad news is that inside the hill Richard Atkinson's tunnel is collapsing." Mr Pitts said "It is collapsing inside the hill at the moment but unless something is done it will reach the surface." The archaeologist said "absolutely unique ecological deposits" within the hill could be harmed if the side of the hill gave way, allowing the air to reach them. Modern thinking by archaeologists including English Heritage's own experts is that the Atkinson tunnel should never have been allowed to be dug in the way it was, said Mr Pitts. He said: "It is evident that the tunnel was never properly backfilled and that has led to voids being created inside the hill." Three possible solutions are being discussed, said Mr Pitts, who is editor of British Archaeology magazine, which reveals the problems with Silbury Hill in its latest edition, due out on Christmas Eve. One would be to use the bore hole to pump in a chalk slurry to fill the void. Another would be to re-open the Atkinson tunnel and back-fill it properly. The third and most exciting alternative, the archaeologist said, would be to open up the tunnel, shore up the roof and sides properly and leave it open for archaeologists to examine. Mr Pitts said re-opening the excavation would allow archaeologists to examine the structure of the hill and take samples from its interior. He said Prof Atkinson had not completed his report on the Silbury dig by the time he died and most of the samples he took had been lost. English Heritage confirmed that voids had been found in the hill in the area of the Atkinson dig and that methods of dealing with them were being examined. Mr Pitts said: "If nothing is done the collapse will eventually reach the surface." English Heritage still has to repair the collapsed central shaft that left a crater in the top of the hill in 2000. It was given a temporary filling of polystyrene with a final layer of chalk the material originally used to build the hill but no decision has been taken yet about a permanent solution. Since the collapse of the shaft dug in 1776, the hill has remained closed to the public and new fences around its base were recently erected. March 24, 2003 REPAIRS to damage caused by treasure hunters at Silbury Hill are planned - 227 years after their dig. Three years ago, a gaping hole appeared at the top of the manmade hill, which archaeologists say was constructed at least 4,500 years ago. Work by English Heritage in 2001 prevented further collapse and now the same organisation is planning work to repair the damage once and for all. Meanwhile the 130ft hill - whose purpose remains a mystery in spite of centuries of investigation - is to be featured in a Channel 5 television documentary about England's finest ancient monuments. Sited near Marlborough and part of the World Heritage site, which also includes Avebury and its standing stones, the hill will feature alongside attractions such as Dorset's Cerne Abbas Giant and Tintagel Castle in Cornwall. English Heritage spokeswoman Catherine Edey said: "In 2001, English Heritage carried out work to arrest a collapse to the head of a shaft which, in 1776, had been sunk by the Duke of Northumberland to the centre of the hill. "Following this work, a geophysical survey of the whole hill was carried out on our behalf by Skanska Cementation. "Reassuringly, they reported that the hill was a robust structure which was basically stable. "But they identified certain areas which required further investigation." She added that more investigations had been carried out below a blemish to the northern flank of the five-and-a-half acre mound but no problems were found. The current work involves investigating the previously-collapsed shaft, including the consistency of previous generations of backfilling of the 1776 dig. That shaft was dug on the Duke's behalf by miners, after the aristocrat became convinced treasure was buried there. The new work involves the digging of boreholes and extraction of soil samples from the base of the old shaft. Ms Edey added: "The information gathered will help us design long-term remedial work." March 13, 2003 Civil engineers brought in to complete remedial work on hill CIVIL engineers have returned to Silbury Hill to begin further exploration of the prehistoric mound. It's almost three years since an ancient shaft at the core of the hill re-opened leaving a gaping hole. English Heritage was forced to act after the old shaft began to collapse leaving a massive crater in the centre of the 4,800-year-old monument. Now international civil engineering consultants Cementation Skanska have been asked by English Heritage to carry out further tests on the hill. In 2001 the company used pioneering new methods to create a three dimensional picture of the inside of the hill. It bored four holes from the top of the hill to its base to allow sensitive recording equipment to be lowered inside the mound to provide a 3D image of the hill. The material removed during the drilling also allowed archaeologists to see how the hill had originally been constructed between 2800 and 200BC. As a temporary repair measure English Heritage had the crater in the centre of the hill packed out with polystyrene capped with a layer of chalk. But local archaeologists have called for permanent repairs to be carried out to the hill. Plant and mobile offices from Cementation Skanska arrived at the foot of the hill this week. The engineers prepared a mesh surface on the southeast slope to enable equipment to be winched to the top of the hill. English Heritage explained that further tests were needed at the centre of the hill to ensure that the old shaft was adequately filled in. In a statement English heritage said: "In 2001 we carried out works to arrest a collapse to the head of a shaft which in 1776 had been sunk by the Duke of Northumberland to the centre of the hill. "Following this work a geophysical survey of the whole hill was carried out on our behalf by Cementation Skanska. "Reassuringly they reported that the hill was a robust structure which was basically stable but identified certain areas which required further investigations." The work that started this week is on the 18th century shaft. "As part of this assessment we intend to test the consistency of the backfilling in the lower part of the shaft by drilling a borehole through it from the top. "Another borehole will be drilled nearby as a control. The information gathered will help us design the long-term remedial work." |
 
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