Above left English Heritage prehistorian and archaeologist Jim Leary examines an interface between the phases of Silbury Hill. Above Polystyrene blocks placed into the collapsed summit. Right Interior view of the original tunnel, showing evidence of sliding chalk.
Alarge hole had appeared in the top of the huge mound – the largest mound in northern Europe – and something needed to be done about it. At first Amanda was tempted to dismiss the report as being sheer alarmism, but it turned out that it was indeed true: a large hole had opened in the top of the monument and caving enthusiasts were already abseiling down and exploring the crumbling sides.
There have been three major excavations of Silbury in modern times, each contributing to the destabilisation of the mound that led to the recent project to restore it. In order to understand the current English Heritage work there, it is essential to note that it has been clear from the start of the project three years ago that it was intended as a conservation effort, rather than an excavation. English Heritage was on site at Silbury Hill not to dig, but principally to solve the issues caused by previous archaeologists. This priority has been apparent in every facet of the undertaking - in the methodology of intensive sampling, in the recording techniques, and most visibly in the plans to seal Silbury Hill forever. There has been much heated debate about the decision to close completely the mound in perpetuity, and as English Heritage site director Jim Leary says: ‘I feel the responsibility every day, when I’m in the tunnel. I realise that what we are doing inside is the last chance anyone will ever get and no one will ever go back in. It weighs heavily on my mind.’ Backfilling is scheduled to begin on 15 November 2007, when over 500,000 pounds of crushed and liquified native chalk will be pumped into the tunnels and void areas; Silbury Hill will be fully consolidated, never to collapse again.
Excavating Silbury In 1776, the treasure-hunting Duke of Northumberland employed miners to dig a hole down from the top of the monument. He was disappointed in his quest, and it was the remains of his shaft that had reopened and caused the May 2000 cave-in. The second attempt was in 1849, when the newly formed Archaeological Institute engaged Dean Merewether to dig a shaft from the side. He also used miners to dig his
Above Abseiler descending from the top of Silbury Hill after the 2000 collapse.
Below The 1968 lintel for Atkinson’s tunnel. Skanska engineers stand in front.