Excavation Iron Age The Cairns

The Cairns dig diary – day twenty

Dig director sums up a successful 2023 excavation season
Farewell from the team at the end of The Cairns 2023 season. (Holly Young)
Farewell from the team at the end of The Cairns 2023 season. (Holly Young)

Dig director sums up a successful 2023 excavation season

The UHI Archaeology Institute research excavations at The Cairns have ended for 2023. With the archaeology safely covered up, it’s time for site director Martin Carruthers to sum up…

Well, we have reached the end of this season’s excavations at The Cairns.

It’s been an incredibly rewarding season and we’ve learned a lot about the site. We’ve been very busy finalising the recording of the features and buildings and then the great task of covering the trench began.

The Cairns excavation site from the south. (Tom O'Brien)
The Cairns excavation site from the south. (Tom O’Brien)

Hundreds of tyres and many, many metres of plastic, were moved around the site and placed with loving care to protect the archaeological remains from the rigours of the weather for another year. Across all the areas of active excavation, we’ve made real progress and one of the very satisfying reminders of that has been the number of return visitors who have said they’ve seen real physical change in the site.

Firstly, a reminder that we focused on four core areas of the site.

These were:

  • The broch interior, where we wanted to explore more of the interior and its floor deposits than ever before.
  • Examine Structure O and establish the fuller outline of this broch-period village building.
  • Excavate the substantial broch-period midden immediately outside the broch and understand the context of the remarkable “Elder” assemblage and its relationship to this midden.
  • Along the way it has been both expedient and very interesting to open a “fourth front” in the vicinity of building remains that are apparently associated with Late Iron Age building, Structure E.

Living in the broch

The broch interior.
The broch interior.

We were active in the Central, North and the South-east Rooms of the broch this year.

Our aim was to get stuck into excavating these areas, which we have tackled less than some other zones of the broch in previous seasons.

In the South-east Room, our principal objective was to explore the complex hearth deposits of the large hearth that was set in vivid yellow and red laid clay floors. The hearth was every bit as complex as anticipated and dark charcoal rich rake-out on one side yielded a well-preserved whale bone vertebral disc.

The bone disc itself was not burnt, so does not seem to have been fuel used in the fire or been tossed into the hearth to get rid of it. Instead, this piece of whalebone seems to be capping the hearth at the end of its use.

This seems very familiar to other whalebone items found in the South-east Room, and other rooms, of the broch – a closing deposit marking the end of the hearth and this stage of the life of the broch.

The other two broch zones explored, by Rick and team, in detail were an interestingly mixed set of results.

Early on, we established that the Central Room was indeed a corridor space that permitted, and guided, access into both the North and the West Rooms – a “co-axial” passageway as it were. It was very useful to confirm this and it was effectively the last piece of the puzzle in unravelling the nature of how the household moved around the broch from space-to-space, room-to-room, 2,000 years ago.

It seems that the Central Room was not just intended for access, however, as the volume of artefacts and animal bones, as well as stone tools, seems to suggest there were some activities actually taking place there also.

Alannah and her large piece of decorated Iron Age pottery from the broch. (ORCA)
Alannah and her large piece of decorated Iron Age pottery from the broch. (ORCA)

There were profuse artefacts and environmental material, with lots of charcoal, large pieces of broken, but not heavily worn, pottery – some of it decorated – and many stone tools, querns, even midden waste incorporating large chunks of animal bone: seal, red deer, shells and fish bone.

This was a similar assemblage to that previously excavated in the broch’s West Room. Some of the materials here may well be the result of waste that was redeposited from processes under way in other rooms – a way of filling up the inevitable erosion and ruts in what would have been a high-traffic area with lots of Iron Age footfall.

The size and condition of some of the pottery fragments, however, suggests that at least some areas of the quite wide Central Room were not subject to trampling. So, our modern sense of corridors and transitional space as non-places, as Marc Auge, would put it, is misleading, and does not encompass what a passageway might have involved and what it might have meant to Iron Age sensibilities.

In the adjacent, much more “roomy”, North Room, work also proceeded at pace.

Of course, this is also where the massive whale rib came from in week one, not to mention a very well-preserved whale vertebral disc. Judging by their place in the sequence these items appear to have been part of the elaborate “structured abandonment” process under way inside the broch around AD200.

This abandonment cycle consisted of many whalebone fragments, (largely fin whale) distributed around other parts of the broch along with other caches and deposits of artefacts and animal remains at the termination of the broch. The presence of this year’s rib and vertebra in the North Room potentially allows us to establish the upper occupation in the North Room as contemporary with the abandonment-period activities elsewhere in the broch.

Intriguingly, other than these finds the North Room was more scant in terms of finds than the Central Room.

Meanwhile, initial results from the environmental samples processed by Cecily and the fieldschool students back at the UHI Archaeology Institute, show that the samples from the North Room are surprisingly quiet in comparison to other areas of the broch interior, with fairly few charcoal fragments, carbonised cereal grains, or micro-artefacts.

This also makes sense when we consider that relatively few artefacts were hand-recovered from this room during the excavation itself, below the abandonment horizon, at least, where the massive whale rib and vertebral disc were found.

This quietness is not disappointing, but rather very intriguing in what it says about differential use and deposition of the rooms within the broch. It is, after all, the search for these differential patterns that motivates us to carry out our fingertip excavation of all of the occupation deposits in the broch in the first place.

The contrast is useful.

This spatial contrast has been seen before in previously excavated brochs and major roundhouses,where rooms arranged around the north of brochs in Orkney are frequently quiet.

Interpretations of this have varied from sleeping, or storage, areas to more esoteric and ideological matters such as that they were areas associated with death, dark and winter. The latter sees the whole roundhouse as seen as a sunwise calendar of sorts, including busy diurnal and quiet nocturnal zones across the day.

In fact, all these possibilities are viable and need not be exclusive.

A tantalising discovery was that some of the deposits in the Central Room appeared to be very ashy and charcoal-rich. This may yet be evidence of an underlying hearth in this zone of the building. A central hearth would be more in line with brochs and major Iron Age roundhouses excavated elsewhere across Scotland, and beyond, but currently the ergonomics of the way that The Cairns broch is internally laid-out would be highly unsuitable to a central hearth.

Essentially the Central Room appears too small and its upright divisions too high to accommodate a substantial hearth.

Such a hearth would also fundamentally get in the way of the main purpose of the Central Room – a corridor space that afforded access to the rest of the broch interior. Does this hint at a different, earlier layout from the one we currently observe?

Has the interior of the broch been remodelled?

Perhaps, but, at this stage in the excavations, we are seriously running out of any depth of floor/occupation deposits which might indicate that an earlier substantial phase lurks below, and meanwhile the packing stones that secured the orthostats are beginning to emerge, indicating we are reaching their foundations.

A major question for the next season of excavation, then, will be the nature of these apparently in situ central peat ash deposits and the originality or otherwise, of the central fixtures and fittings…

Structure O

A key area of work this year was this broch-period building outside the east-facing broch entrance.

Our aim was to see the fuller footprint of the building and, from there, decide how we could go about planning its excavation.

As things turned out, the overlying features of a revetment wall and extensive associated paving were more extensive and the revetment wall more substantial than we had thought.

The hearth-like feature in the paving over Structure O. (ORCA)
The hearth-like feature in the paving over Structure O. (ORCA)

A central feature set within the paving – which we confirmed to be a hearth – was also an intriguing development. We believe these paved, revetted areas – tiers around the remains of the broch – were outdoor, unroofed platforms and not houses as such, and appear to be marking-out the broch ruin-mound.

In a curious way, they simultaneously drew attention to the mound/ruins and at the same time capped/sealed it – a classic bit of the human paradox of remembrance and amnesia.

The broch mound clearly had lasting significance long after the period when it stopped being an upstanding building that people could walk into and around.

These revetted tiers of masonry are possibly similar to the Iron Age slab platforms found on the mound at Mine Howe in Orkney’s East Mainland, or even the Iron Age treatment of the mound at the Ness of Brodgar’s Trench T, where an Iron Age revetted ditch was cut into and, bounded off, the Neolithic mound.

They all seem to reflect a strong Iron Age interest in important places of the past, and they also seem to represent a certain formality in accessing that past, even control over it.

Regulation through prescribed routes, paths, barriers was created through the architecture and so the precise way in which the remains of the past could be encountered was controlled.

Someone stamped their official version of the past on the site during this phase. It’s arguably a result of the political use of the remains of the 1st Century BC/AD during the 5th Century AD, or rather the presentation of a specific past for political reasons.

It will be intriguing to see what the environmental samples from the hearth deposit come back with and whether there are any indications of what kind of material may have been burnt – whether food or other items.

Overall, our work in Structure O became absorbed in unravelling the complex, and interesting features that cap the broch-period village building. However, work in the next key area allowed us to achieve the objective of understanding the layout and morphology of Structure O after all…

Contextualising the ‘Elder’

The whalebone vessel, which contained the human mandible, with the deer antlers and saddle quern outside the broch entrance. (ORCA)
The whalebone vessel, which contained the human mandible, with the deer antlers and saddle quern outside the broch entrance. (ORCA)

The next key area that we had earmarked for investigation this season was the area immediately outside the broch, known as the broch “frontage”.

Previously, it was the site of the discovery of the remarkable “Elder” assemblage.

You may recall that this consisted of a human female mandible placed in a massive whalebone vessel along with two new-born lambs, and arranged – indeed almost choreographed – with two red deer antlers propped against the whale-vessel and a massive saddle quern placed to pin it against the outside of the broch wall.

We knew this deposit dated to very close to the end of the broch, around AD200, but we wanted to see more of the actual setting of this astonishing formal act of deposition.

It was not long before the fuller sense of the Elder assemblage’s context came a bit more into focus.

The niche wall with its in-built saddle quern and little stone tool positioned against it. (ORCA)
The niche wall with its in-built saddle quern and little stone tool positioned against it. (ORCA)

The skinny wall leaning directly against the broch outer wall, which we had previously glimpsed during the excavation of the Elder, was fully revealed and it turned out to be a very intriguing feature.

Essentially, the discrete wall feature looked a bit like a Neolithic “dresser” of the type found at Skara Brae or the Ness of Brodgar.

The wall feature had a cubby, or niche, in its centre, and the masonry on either side was fashioned from a beautiful large, reused saddle quern, set on its edge, and a rounded stone pillar base, respectively.

Holly and her team, Chloe and Anna, uncovered stone tools on top of the wall, and in the niche. Meanwhile, a stone tool also lay directly in front of the grinding surface of the in-built quern.

Holly holding a tray of masses of animal bone from the midden outside the broch. (ORCA)
Holly holding a tray of masses of animal bone from the midden outside the broch. (ORCA)

From this it looked almost as if the quern was still in use, but, of course, having been placed on its side and built into the “niche-wall”, this was not in fact the case. A feeling of formal choreography seemed close to hand in all of this, especially when put together with the content and expressive arrangement of the Elder assemblage.

The niche-wall is an unusual feature for the Iron Age.

Small cupboards set in masonry walls are not in themselves unusual for Iron Age Atlantic Scotland as a cursory visit to the Iron Age village around the Gurness broch swiftly reveals. We have also found other little cubby/cupboards built into structures at The Cairns.

Nor are stone features set immediately outside broch walls particularly rare. See, for example, the so-called “dog-kennels” outside the door of many.

The combination, however, of cubby-hole, and the discrete stand-alone, dresser-like structure of the niche wall is more unusual. And, of course, it must be remembered that it was against this feature that someone chose to place the Elder assemblage, marking the end of the broch.

This does make me wonder whether the role of this feature was somewhat special and even cultic from the outset. Is it too fanciful to think of this as a house-shrine for the broch – the place where the mortal remains of the “Elder” were placed with considerable apparent ceremony at the end of the broch?

While excavating the frontage area, the team were also able to investigate the profuse shell midden here.

Again, a sneak preview of this had been obtained during the excavation of the Elder assemblage in 2016. This shell midden was indeed profuse and was also laced with ashy deposits replete with organics. But also, importantly, lots of animal bone.

The human molar discovered in the midden outside the broch. (ORCA)
The human molar discovered in the midden outside the broch. (ORCA)

As though to emphasise the strong connection between this midden material and the original Elder deposit, a further human tooth emerged from the soil matrix of the shell deposit, with wizened roots and very flat cusps.

This tooth very likely belonged to the elderly female, but had been dislodged in the “post-burial environment”.

Fascinatingly, when our UHI colleague Prof Ingrid Mainland, a well-known zooarchaeologist, was able to visit the site, she identified lots of the animal bone as red deer.

What’s more, it was also possible to identify several deer matching leg bones across adjoining articulated anatomy – very likely showing that these represented joints of leg meat.

Picture: ORCA
Multiple red deer bones from the midden at the frontage area of the broch. (ORCA)

This echoes the massive volume of red deer from inside the broch (the West Room, especially).

Overall, this shell and faunal midden is going to be highly informative when fully analysed and the food remains almost certainly represent waste from the broch itself, related to near the end of the structure at its closure.

In excavating the shell midden and the niche-wall, Holly’s team uncovered the Western wall of Structure O.

It curved gently to the south, away from the previously established north-western corner of Structure O and shows how these broch-period village buildings were often quite irregular in shape and are not amenable to a join-the-dots approach to excavation.

Door pivot stone and threshold sill-stone of Structure T emerging next to the niche wall. (ORCA)
Door pivot stone and threshold sill-stone of Structure T emerging next to the niche wall. (ORCA)

The wonderful thing about the appearance of the West wall of Structure O in the broch frontage area is that it also formed the inner wall face of another building – or large feature – set even closer to the outside of the broch.

This structure, (now named T), must also be another contemporary building to the broch occupation and it possessed a lovely door pivot stone and clear threshold slabs and sill, where its doorway accessed the central passageway that led out from the broch door through the village complex.

This allows us to see something of the organisation of the village at The Cairns during the Middle Iron Age period and how similar it appears to have been to sites like Gurness (Aikerness, Evie) and Howe (Stromness).

That’s a great help in understanding more of the nature of the broch exterior and the extramural complex of buildings that surrounded it 2,000 years ago.

In total, the work at the broch frontage zone has revealed a vivid sense of the context and setting of the Elder assemblage, uncovered details of the broch-period village, including new structure T.

The work here also permitted the fuller form and outline of Structure O to be made out and allowed us a rare window on to food and refuse towards the end of the broch. Not bad at all for a relatively small portion of the site!

The Late Iron Age cells

On the south-east side of the main trench an array of well-built walls, cells and stone partitions emerged from the hard work undertaken by Anthea, Deryck, Duncan, Iain, Felix, Zoe, Katie, Mai, Henry and Ole.

These structures are well-preserved, with substantially coursed masonry walls. The fill of this multi-cellular structure – or possibly structures – includes some heavy rubble was deliberately back-filled, and swiftly so, based on its voided, largely soil-free nature.

We had been working with the hypothesis that these cells were an integral part of nearby Structure E – a 7th Century AD building we excavated some years ago – the builders of which truncated the remains of the broch ruins, establishing a sound foundation for it.

Towards the end of week two, however, we got an interesting surprise when a section of straight walling emerged (typically from under our control baulk: i.e.: the edge of the excavated area) that threw that hypothesis into doubt.

The wall did not fret into Structure E, but rather demarcated the multi-cellular area as a discrete building.

We’re now looking at an entirely different building from Structure E, one that seems to have been constructed later-still, thus becoming the latest Iron Age period building on site, that we know of, prior to the arrival of the Norse.

Important finds: Associated Bone Groups

We uncovered no less than five separate Associated Bone Groups (ABGs) across the site.

These are articulated whole animals, or portions, of animals deposited. They seem to be different from the normal animal bone in middens and are placed in particular places and spots on site that are not associated with faunal refuse.

Lots of these have come to light on site in the past but this season is something of a bumper year for them.

Often seeming to be associated with periods of change on site, such as new buildings being constructed or old ones being decommissioned, the ABGs seem to occur when there is seminal transformation and alteration under way and appear to be very deliberate acts or offerings.

They will yield huge amounts of information, both about human-animal relationships during the Iron Age and also the nature of formal deposition/offerings.

Important finds: querns

Another find type, amply represented on site this year, was stone tools and especially querns.

Large numbers of these grinding tools, used for processing cereals and other materials, have always emerged on site, however there was a bumper crop this year, with greater numbers, and a more extensive variety than ever before.

Large saddle querns, mortar-like “knocking-stones”, top-stones (or rubbers) and fragments of rotary querns emerged in significant numbers this year, bringing the total up to around 60.

Of course, there were also examples of querns reused and built into walls and features like the “niche-wall”.

The presence of all these major tools really accentuates the massively productive capacity of the site as a farming community during the Iron Age. The querns will continue to be a special focus of the project moving forward.

And finally…

All in all, it has been a very fruitful and enjoyable season, with a lot learned about the nature of the site – from the broch beginnings to the late Iron Age structures.

Major features of the site such as the broch floors, the contemporary village, and midden will immeasurably help us to understand the character of the settlement, and its finds this year have been very rich and highly useful in elucidating issues relating to dating, the status of the community and depositional practices.

Now, some thank-yous!

The Cairns team photo marking the end of the first UHI Archaeology Institute fieldschool. (ORCA)
The Cairns team photo marking the end of the first UHI Archaeology Institute fieldschool. (ORCA)

I’ll take this opportunity to thank the entire project team across the four main weeks of the field work, for their unstinting good humour, patience, and enthusiasm.

Without them, the site would, of course, remain unexcavated and it’s only through their sterling efforts that we begin to understand what was going on at the site 2,000 years ago.

This year the public have visited the site as before.

We benefitted from a large number of visitors and they were very generous in their support for the project. Donations will now be spent on important aspects of post-excavation work, such as additional radiocarbon dating. I would like to thank all the visitors and donors, and for allowing us to communicate our findings from the site.

Finally, I would like to thank Charlie and Yvonne Nicholson, and all of their family and friends in South Ronaldsay, for their many acts of assistance and generosity.

Our time at The Cairns is made possible, enjoyable, and very amiable, due to their great kindness.

Thank you!

Martin Carruthers
Site Director