Will Silbury Hill wash away? I think the radio presenter who asked me that was probably joking. It rained a lot a decade ago, and the top of the hill collapsed inwards when poorly backfilled old excavation tunnels slumped. English Heritage fixed it, and really it’s pretty stable now.
It’s been raining a lot again, and as has happened before, the old ditch around Silbury is now flooded. It’s a good time to see the site (especially if the sun shines), as it’s easier to imagine how it might have appeared when it was built – and when its original purpose and meaning were driving events and perceptions in the final neolithic/copper age around 2400BC. So here, in case you can’t make it out there, is how it looked this week.
The very base of Silbury is solid chalk rock, but most of it is quarried and mounded rubble, some of it at least packed within rough chalk walls that apparently help retain the hill’s shape. That rubble had to come from somewhere. The easiest way to see the quarry is to look at a plan – because it runs around the hill, you can’t see it all in one view on the ground.
The above is from a pamphlet published by the BBC to accompany its broadcast of Richard Atkinson’s excavation in 1968 and 1969 (there is advice to visitors – you weren’t allowed in the tunnel; I remember Lance Vatcher, who supervised the dig, telling me how a field was used as a car park and the public had to be towed out of the mud). I bought the guide at the museum on my first visit to Avebury when I was at school.
I’ve coloured the quarry blue. As Jim Leary and Dave Field have explained, the Beckhampton brook flows into this and would have filled it with water; close by is the spring at the source of the river Kennet, adding to the watery significance of the location.
Note how on the south edge of the hill is a small stretch of ditch isolated by low “bridges” on either side.
Atkinson dug a trench here, but it didn’t reach the bottom. This ditch cannot have filled with spring water, but could it have held rainwater? Were the “bridges” to give access to the hill (if so, perhaps there were wooden structures across them that might have left evidence excavation could uncover)? Or were they – instead or in addition – designed deliberately to isolate that bit of ditch, for some unknown purpose?
Such association of neolithic monuments and water has long been commented on by archaeologists. Leary and Field note the scarcity of burials in this era, and suggest people might have been casting cremation ashes into rivers. Was Silbury’s moat a collective grave, a watery entrance to another world?
The idea can be tested. If sufficient quantities of ash were cast into the ditch, some might remain in the deep silts. These silts can easily be cored and sampled. Several recent studies have successfully extracted fossil DNA from sediments. It seems worth checking to see if, deep below the water and the silts in Silbury’s ditch, still lie traces of the people who may have looked to the hill to mark their passage into history.
“Great monuments: great rivers”, by J Leary & D Field, British Archaeology Sep/Oct 2011/120
The Story of Silbury Hill, by J Leary & D Field (English Heritage 2010)
This is what Silbury looks like when it’s dry.
And of course, as Jim Leary says, please don’t climb all over the hill, it’s damaging and disrespectful!
Mike Pitts – Digging Deeper 
Fascinating. I’ve been to Silbury Hill and I had never imagined that it might have been surrounded by water. Could it have had a defensive/military function as well?
IS Silbury the unique artificial hill of its type or are there any others remaining that we know of?
Thank Alastair. It looks an unlikely defended site, down in the valley when in earlier centuries people had been building defended enclosures on hilltops with earthworks and timber. Just a little further down the river at West Kennet were two huge timber palisaded enclosures. Though poorly dated (we need new excavation), they are later neolithic and broadly contemporary with Silbury; a comparable, and even larger, palisade was raised on a hilltop in Dorset, at Mount Pleasant, inside a large henge earthwork.
The question of large round mounds is interesting (note that Dave Field has argued from high resolution survey that Silbury is not technically so much round, as polygonal, with nine sides – really quite subtle, so perhaps an engineering artefact rather than for visual effect, though this needs to be tested by excavation). There was a tradition of building these mounds that loosely falls between the long barrows of the earlier neolithic and the small round barrows of the early bronze age. But they are less common than either of those forms, more varied and less consistently associated with burial. Silbury always stood out as being quite exceptional for its size, and still does. But what’s interesting is that recently two other large Wiltshire mounds, very large if not quite so as to challenge Silbury, long known about but less considered, have been revealed to be of the same age. One stood at Marden, but was demolished early in the 19th century; and the other still rises over the grounds of Marlborough College. The latter is on the same river Kennet as Silbury; Marden is near the source of the river Avon. See the references above, and below.
Round Mounds & Monumentality in the British Neolithic & Beyond,
ed Jim Leary, Timothy Darvill & David Field (Oxbow Books 2010)
Fantastic photographs, I’ve never seen Silbury like this before, seems to make the mound even more enigmatic.
Thanks Mike
I’ve old black and white family photos taken of Silbury Hill in the 1950s when I was a child, and it’s curious to see it like this. Very interesting, too.