The Hole in the Hill
The collapse of an antiquarian shaft
On 29 May 2000 a hole unexpectedly appeared on the top of Silbury Hill. A shaft had become open to a depth of 14 metres. Despite attempts to safeguard it, in December the top collapsed to leave a large crater [1], damaging important archaeological deposits.
English Heritage immediately began research to establish the cause of the collapse. It became clear that a vertical shaft originally sunk in 1776 by the duke of Northumberland to explore the centre of the Hill had reopened. Despite appearances to the contrary, it had never been properly filled and had actually reopened on several earlier occasions.
English Heritage enlisted the help of engineers and engaged Skanska Civil Engineering who temporarily filled the hilltop crater with polystyrene blocks [2] beneath a protective capping of chalk [3]. This prevented the sides of the crater from collapsing further, protecting the fragile archaeology from damage.
Further survey revealed that horizontal excavation tunnels at the bottom of Silbury, dug by Dean John Merewether in 1849, and by Professor Richard Atkinson in 1968-9, were also collapsing slowly upwards through part of the Hill.
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