Excavators continue to uncover the story of a South Ronaldsay broch
As any visitor to any of Orkney’s surviving brochs will attest, they were formidable structures. But what is perhaps not so obvious is the technical skill of those responsible for their construction.
There’s no doubt it took a certain level of expertise to build these huge stone towers, but this year’s excavation at The Cairns, in South Ronaldsay, continues to show that, for this particular structure at least, style was every bit as important as function.
Built into the lower section of the five-metre-thick broch walls are three small teardrop-shaped cells — chambers that are so tied into the masonry that they must have been intended when the structure was planned.
In charge again this year was Orkney College UHI lecturer, Martin Carruthers.
He explained: “The sheer scale of brochs meant that they tended to follow a specific architectural design. You have this narrow entrance passage, the only break in the typical broch’s wall, which was kept narrow so the massive weight of the masonry bearing down on it was spread out.
“But here the broch builders have incorporated a series of chambers into the fabric of the lower wall. These chambers were beautifully built, and certainly no afterthought. The builders knew exactly what they were doing, because even now, thousands of years later, there has been no structural failure in the wall sections around them.”
Two of the chambers were found to have been carefully “plastered” with coloured clay and, in one case, decorated with the imprint of seashells.
The smallest of the three was accessed by a small opening a few feet from the foot of the wall, and had been rendered with red clay.
“This wasn’t a space people were entering — it’s much too small — but it was something they were putting items in and taking out. But whatever it was for, they went to an awful lot of bother decorating it with red clay.
“Why go to that bother? When you think about the monumentality of this structure — a huge brute of a building, with massive pieces of masonry and subsequently a tremendous height and weight — in the middle of it there are these architectural features of extraordinary finesse and delicacy. They are beautiful in their own right.
“But, from a practical point of view, it makes absolutely no sense. This is one of the biggest brochs we have here in Orkney — it’s 11.5 metres in diameter, a wee bit bigger than Gurness or Midhowe, so it’s pretty spacious inside.
“So, when there was at least one other storey above it and all the potential attic space, who thought, when they were building this, ‘Do you know what we really need? Some extra, tiny little cells built into the weight-bearing lower walls.’”
He added: “In a bygone age, people looking at brochs, and their layouts and features, thought that when it came to proportion and stability the builders didn’t understand the concepts.
“But they clearly did. They just had a different purpose and way of thinking, with their traditions, culture and other agendas driving them on.”
While brochs tend to be regarded as utilitarian structures, meant to look imposing from the outside, it is now clear that, at The Cairns at least, the grandness of the stone tower’s exterior was mirrored in the interior. The builders went to some lengths to make the inside of the broch as impressive as the outside.
The presence of the chambers has confirmed that The Cairns broch had a solid lower wall — in contrast to the double-skinned walls found at the Broch of Gurness, for example.
Martin explained: “What it looks like, at present, is that the base 1.6 or 1.7 metres of the wall is solid. Above that, the walls were constructed in typical broch fashion — dual skinned. We know that, because we’ve got the remains of a staircase built between these two walls in another section of the site.
“While it’s been said that the vast majority of brochs in Orkney are solid-based, typically, the two most celebrated brochs in the county are both ground-galleried, or double-skinned.”
The solid base of The Cairns broch meant that the builders could have built a higher, more-imposing tower. However, the inclusion of the cells, and the structural limits they imposed, suggests The Cairns broch was perhaps not very high.
But, however high the broch was, an impressive, spacious ground-floor space was clearly part of the original plan.
“As time goes on, and we get deeper and deeper through the floor deposits towards the original occupation layer, there’s still no sign of a scarcement — the stone ledge, built into the wall, for the upper floor to rest upon.
“We’re down about two metres now, and it’ll maybe be 2.5 or three metres by the time we reach the primary floor layer. This suggests that, if this structure did have a scarcement, it must have been quite high up.
“Sometimes you can get scarcements appearing as low as 1.8 metres, but we’ve more than that visible now and there’s absolutely no sign whatsoever. So we’re thinking that it must have been above the three-metre level.
“I can’t believe that there isn’t, or wasn’t, a scarcement, because the staircase must have led out onto an upper storey, otherwise why build it? It would therefore seem that this upper storey sat pretty high up.”
He added: “I always think that the idea of multiple-storied interiors, starting maybe two metres up from the base and then another a couple of metres above that, is squandering the grandeur of the interior, because it necessitates very low ceilings.
“It has often been suggested that the ground floor in brochs was where there’s all sorts of activities taking place — industrial and domestic — as well as the storage of produce, and that the living quarters were on the upper storey.
“But in Orkney, because of the quality and formality of the stonework, the ground floor was more than just a space for wintering your livestock — it was very much used as more than just a practical space. And at The Cairns this certainly seems to be the case.
“Maybe this broch’s ground floor was intended to be quite a high-roofed, grand space as you walked in it.
“Basically, anyone entering the doorway would encounter a large, spacious chamber with a central stone-lined ‘corridor’ leading right into the centre of the building, and a boxed-off, square central area. From here, you had access to the side areas of the lower floor, which had been, at least in later life, partitioned off.”
This year’s excavation has cleared a substantial area of the broch floor of the rubble that had been deliberately used to fill in the interior.
Martin explained: “We’ve now got two-thirds of the interior of the broch exposed, and we’re hoping to get some of the ramshackle stone debris down next season. That will open it up even further, but there’s still a lot of rubble to come out.
“The stage we’ve reached this season has us down on the floor layer that represents the last gasp of activity inside the broch — sometime after AD 200 — just before they filled it with rubble. But what we’ve got this season is very different to what we had last season in the opposite side of the chamber.”
Last year, the excavators came across evidence of fish processing on an industrial scale but, this year, a partitioned-off section of the ground chamber has yielded huge amounts of dark, ashy material, as well as bone from cattle and juvenile sheep — the lamb vertebrae, in particular, should yield good radiocarbon dates.
In addition, the section has produced good examples of Middle Iron Age pottery, which ties in with the fishbone deposits found last year.
“These fragments will be tested for lipids to see what these pots contained. With the discovery of a broken stone lamp lying alongside a cache of pot fragments, it is tempting to wonder whether fish oil was perhaps one of the substances being stored.
The lamp had been deliberately broken in half and buried face down, prompting the idea that it was perhaps part of a decommissioning deposit.
“Just as last year, we’ve got more examples of scorched wall sections that show they had set fires right up against the walls — all around the ‘clockface,’” said Martin.
“Once I did think that these fires might have been part of the initial decommissioning process. That might still be the case, but the association of the burnt areas with the fish processing left us wondering if what they were doing was deliberately creating smoke — maybe using the broch shell as a smokehouse for fish, perhaps meat.”
It is this attention to the organic remains on site that is particularly important to our understanding of the broch settlement’s life.
Whereas excavations in the 19th and early 20th centuries focused solely on the architecture and artefacts, the work at The Cairns will provide an unparalleled glimpse of everyday life on the site.
“Rather than shovelling the organic remains and floor deposits out to get to the tangible archaeology, we’re excavating the soft deposits very carefully and in a very modern fashion — we’re not wasting a single thing.
“The deposits recovered this year and last represent the last moments of life within the broch and will hopefully help us understand how and why these structures were abandoned.
“It’s not even appropriate to call it a sampling process, because sampling implies that we’re just taking bits and pieces here and there. That’s not the case. We’re taking everything, and it’s all going to be analysed.
“This is going to be one of the few occasions in the modern era that we will be able to excavate the occupation and floor deposits within a broch.
“And we still have every indication that it’s going to be at least 50 centimetres, if not more, of deposits to work through before we reach the primary floor level.”
Going back to the fish deposits, for example, all the remains were sieved and sorted, resulting in proof that thousands upon thousands of fish were handled within the shell of the broch.
These fish were all inshore species, such as sillocks, and were on a level hitherto unrecorded within the Middle Iron Age.
Highlighting the importance of finds that would have been discarded by the antiquarians is a small piece of charcoal found beneath a stone at the bottom of the smallest wall chamber.
At present, the date of the broch’s construction is not clear, but is likely to be at least 200-100BC — although Martin suspects it could be as early as 500BC.
But this piece of charcoal, which was found alongside some discarded shells, will hopefully provide a radiocarbon date that places the building project within a specific time period.
Earth-house still has secrets to give up
When the broch was finally abandoned and filled with rubble – sometime between AD84 and AD210 – an underground earth-house – or souterrain – was created that incorporated the entrance of the abandoned broch.
As I’ve written before, the “destruction” of the broch wasn’t a simple land clearance – destroying the old to make way for the new. Instead, it is clear that care was taken to include elements of the original structure into the new construction.
This year, the souterrain was a focus of excavation, and the four-week dig has shown that the situation surrounding this subterranean structure was much more complex than originally thought.
Previously, and mirroring the situation at the nearby Windwick earth-house, it was thought that a structure found above the souterrain was contemporary – perhaps part of whatever went on under the earth.
Martin said: “The structure above the souterrain had a nice, clay floor surrounding the hearth but, as we excavated the floor, it became clear that it ran over the material choking the entrance passage of the souterrain – in other words, the building was built after the souterrain had been abandoned and blocked off.”
The earth-house proved equally enigmatic.
“The situation regarding the souterrain is considerably more complicated than we thought. It has secrets yet to give up before we can claim to truly know all there is to learn. The fact that there appears to be an even more complex subterranean warren of activity is going to make for exciting work next season.”
A centuries-old tradition of metalworking
Away from the broch, a new trench was opened this year to try and pinpoint the extent of the 80-metre-diameter ditch that surrounded the settlement.
Martin explained: “The aims this year were to do more work in the broch and the souterrain, and have a look for the ditch. We’d carried out new geophyics scans, and they were showing us the extent and location of the ditch. To confirm the scans, we opened Trench T and found the remains of a wall.
“Excellent, we thought. This is going to be the revetment of the ditch, because it’s quite a well-built wall and it’s curving roughly in the way that we expected the ditch to be coming around.
“But typically for The Cairns, it wasn’t as simple as that. It now appears that the ditch had been deliberately filled in entirely, and the wall constructed on top. Why? It may be some kind of very late attempt to reformalise or re-establish the boundary that the ditch once represented.”
It was on top of the wall that some of the star finds of this year’s excavations turned up – extensive evidence of very fine metalworking that was taking place on site.
“We’ve been recovering dozens and dozens of ring-necked pin moulds.
“They’re typical Middle Iron Age, so again, it looks like just as our broch seems to go out of use, and its major period of occupation ends, the ditch, was filled up.
“By the Middle Iron Age there would have been no visible traces of the ditch, but someone was out here casting these beautiful, bronze ring-headed pins on top of the wall and the rubble behind it.
“There’s no real evidence for any structures relating to this metalworking — it appears they were carrying it out in the open air. Maybe that was a wise thing? Maybe there were buildings nearby, but they were actually coming outside to break the moulds to get to the artefacts within.
“One or two of the moulds showed that the casting process had failed because they were fragmentary, but the two halves were still stuck together, and there were piece of copper alloy in the vicinity as well.
“When we get these x-rayed we’ll maybe see that there’s still bits of the copper inside.
“When we started getting the mould fragments appearing in Trench T, I thought we were looking at midden material from the metalworking workshop that was built into the broch remains, but then we realised they were for ring-headed pins, which we know date from a few centuries earlier than the stuff that was being produced up in the workshop.
“What is interesting, therefore, is that it seems there was a longer-lived tradition of metalworking on this site.
“This, together with more evidence of textile production, leads me to wonder whether one of the things this community was specialising in was in the finer things in life — the bronze work is all jewellery-based, it’s all personal adornment; the weaving combs were used on braids or hems — fairly elaborate pieces of material.
“It’s maybe too early to say that this typifies the whole site, but so far that emphasis on how you clothe and adorn the body makes you wonder if they were producing items that people wanted to wear.”
The excavation team would like to thank landowners Charlie and Yvonne Nicholson for their support.