Flooded entrance section of suspected subterranean chamber discovered beneath South Ronaldsay broch
For years, these elaborate underground chambers were dismissed as mere wells — incorporated into the brochs as a practical source of water. But the re-opening of Minehowe — a massive subterranean structure that served no practical purpose — in 1999, began to cast doubt on this long-held definition.
Why go to all that bother to create a difficult-to-access chamber, digging through bedrock, building steps and, in some cases, creating beautifully corbelled ceilings, when a hole and a bucket on a rope was a much simpler solution?
Along the same lines, Orkney’s earth-houses were generally considered as having a practical purpose — storage, for example.
But the same question applies — why go to the trouble of constructing elaborate, difficult-to-access underground chambers just for storage? There was no need.
After three years’ work on an earth-house at Windwick, in South Ronaldsay — the first excavation of an undisturbed earth-house in “modern” times, and with the benefit of the latest archaeological techniques — Orkney College lecturer Martin Carruthers was firmly of the opinion that the earth-houses had as much to do with ritual, and in particular the dead, as a place to stash that season’s crops.
A short distance from the Windwick souterrain is The Cairns excavation site, where Martin Carruthers is now the site director.
Alerting me to the remarkable, and purely accidental, discovery last Friday as a “wee surprise”, Martin explained that the entrance to The Cairns’ broch “well” was found while excavators were working in the northern section of the broch’s interior.
“Ursula, one of the volunteer diggers, had momentarily left where she had been trowelling a very nice, charcoal-rich hearth area to fetch an item to help her record her finds.
“She walked to the north wall of the broch interior and then it happened — I heard a crack, and a little gasp of surprise as she put her foot through a small slab. This was followed by a muffled plop as the slab fell into water!
“After we regained our composure and checked Ursula was okay — she was, thankfully — we stood in awe at what she’d accidentally discovered.
“Through the hole, we saw a water-filled subterranean feature. At first glance it seemed quite small, and we couldn’t see much because it was dark and full of water. What we could see, however, was substantial and well-built.
“Pushing a long cane into the opening, against the area we thought was the chamber’s end wall, revealed that what we thought was a stone slab was, in fact, a lintel, and that the underground structure proceeded onwards underneath it. In fact, I could meet no resistance at all under this lintel!
“We can’t say what lies beyond this apparent ‘inner entrance’ — we can’t see that far into it — but, given the architecture of other brochs, I suspect we have steps leading further down into the earth.”
Back above ground, the chamber proved to be something of a double surprise.
Aside from the discovery itself, the excavation team thought they had some way to go before reaching the “primary floor” — the earliest level of activity within the broch.
The stone-covered access “hatch” was not simply a case of placing a slab over a hole. A formal stone setting flanks the entrance.
“This is intriguing in itself,” said Martin. “We were all thinking that we had some way to go before reaching the bottom of the occupation deposits, but it may be that as the level of detritus within the broch increased, the later occupants were raising the level of the entrance, and related stonework, to compensate for the rising floor levels.”
But while the discovery came as something of a shock at this stage of the excavation, Martin explained that it was perhaps not unexpected.
Indeed, going through my notes from previous seasons at The Cairns, Martin had indeed postulated that they might come across a Broch of Gurness-type underground chamber.
“If we accept the theory that life within Iron Age structures was ritually structured, then the discovery fits just as you’d expect it would,” said Martin.
This theory has it that life in the Iron Age was organised around a light, activity-based southern side, with a dark, northern side for sleeping and storage.
In The Cairns broch, the entrance to the suspected underground structure lies in the northern section of the interior — an area that represents encroaching darkness, death and sleep.
In addition, it may be that access to the lower levels was by a walled-off “room” in the broch — remnants of the stones that partitioned off this room are still standing.
While they could date from the later phases of the broch’s use, if this is the case it shows that the inhabitants were respecting that which went before.
But the mystery will have to remain for the time being.
Although there were plans this week to pump out some of the water, under controlled conditions, to get a better look at the underground feature, excavation will have to wait.
The stonework around the entrance is in a poor condition, so excavating through it is out of the question, for safety reasons.
If, as it certainly appears, the underground structure continues onwards and downwards, it would require a massive excavation in its own right, which, again for safety reasons, would mean the archaeologists would have to go in via the suspected chamber’s roof — a roof that remains under a considerable amount of rubble thrown in during the Iron Age, when the broch was levelled.
But, if and when this excavation takes place, it is hoped that the undisturbed nature of whatever lies within — not to mention the fact that the waterlogged anaerobic conditions, where oxygen is excluded, will have preserved any organic material — will reveal as much about the purpose and significance of these underground broch “wells” as Martin’s previous work on earth-houses has.