The curious case of the Cairns ‘broch’

It’s definitely broch-like, but is it a broch?

That’s the question still facing the archaeologists at the ongoing excavations at the Cairns in South Ronaldsay.

Overlooking Windwick Bay, the Cairns is a massive archaeological jigsaw puzzle, with a sequence of Iron Age buildings, representing centuries of use.

An overview of the Cairns excavation site. The roundhouse remains are in the top left, with the entrance passage to the left of the picture. Structure B complex is in the top right, while Structure C is in the bottom middle. (Orkney College)

The first building on site was a massive broch-like roundhouse – with five-metre thick walls forming a structure with an exterior diameter of 22 metres.

This structure, in particular its interior, has been the focus of much of this year’s excavation, with the archaeologists painstakingly removing huge quantities of rubble to reach the floor level.

As a result, a clear picture has emerged of the inside of the ‘broch’ building. A large area of the interior and its entrance has been cleared to reveal impressive internal fixtures and fittings across about a third of the building. These are beginning to show how the interior was divided up and how the architecture enabled people to move around the building — at least during one stage in the life of the building. The fixtures uncovered so far probably relate to a later period of the roundhouse’s life and, as such, are covering earlier fittings.

Getting down to the floor level of the roundhouse. (Sigurd Towrie)

Continued excavation will allow the archaeologists to chart the development of the structure’s interior – hopefully from its construction to its abandonment.

Although on first glance it looks like a broch, such as at Gurness and Midhowe, the Cairns structure doesn’t fit with the “classical” definition of the fortified towers.

At the helm again this year was Orkney College lecturer Martin Carruthers.

He explained: “What we’ve got is this early broch-like structure – a dominating, big structure, with big, thick walls and a very large internal area.

“In essence, the features here are very conventional for a broch – we’ve got the intra-mural staircase, for example, leading to a ‘second floor’ – and you could take the floor plan and overlay it on other broch sites. But we’ve also got these other features, such as a series of tear-drop shaped cells built into the walls, that are not found in Orkney brochs.

“We can now see that these chambers were a weak point in the overall design. Their inclusion meant that sections of the roundhouse walls were unable to support the sheer weight of the masonry above them. These architectural ‘problems’ leave me wondering if we’re dealing with a period of experimentation – an early attempt at broch-building from a time when the design and traditions surrounding broch-building hadn’t quite been finalised or fixed.”

This, together with the huge, 11.3-metre-diameter, inner chamber, may explain why the Cairns structure was perhaps not as high as the Broch of Gurness, for example.

“I just think the whole thing couldn’t have been very stable at a very high height,” said Martin.

As reported previously, Martin suspects that in the Iron Age, the roundhouse might have been the focus of the area – an importance the later structures perhaps sought to exploit.

However, rather than sitting in the heart of the area’s farmland, he feels the house occupied a more peripheral position. He is of the opinion that the structure, although probably not as tall as other Orkney brochs, sat on the high ground overlooking the arable fields on the south-facing slope, with the hill land behind. It was meant to impress and to those in the houses in the valley, and working the fields, the structure would have been an imposing sight. Dominating the ridge above them, perhaps it was meant to reinforce the status, wealth and power, of the owners to those working in its shadow.

But the fact remains that although the Cairns structure contains features not found in Orkney, its design is paralleled at sites in Caithness – perhaps not surprising given the location – in particular, Crosskirk, which may have dated from around 700-350BC.

“With the Cairns structure, we need to wait for various dating results, but from pottery found in the structure, I think we’re looking at a similar very early date, perhaps around 500BC.”


Reusing the roundhouse

This Caithness connection resurfaces when it comes to how the site was used after the roundhouse fell out of use.

Martin added: “What you tend to see around brochs in Orkney, is a reuse of the land surrounding the tower. The broch is left alone and other structures are built over the top of the broch settlement, for example.

“But in Caithness, there’s a tradition of building into the broch itself – where the later structures ‘bite’ into, and incorporate, the original fabric of the broch. And that’s what we have here.


After the Cairns roundhouse fell out of use, perhaps around 100BC, and had possibly begun to collapse in on itself, later Iron Age inhabitants of the area deliberately pushed the walls into the centre of the structure, taking them down to a level that left a useable, stable, platform they could build upon.

The south-eastern entrance to the roundhouse was also carefully blocked off – creating the “chamber” discovered by the Rev Alexander Goodfellow, Minister of the United Free Church Congregation in South Ronaldsay, in 1901. Peering into the darkness, Goodfellow saw stone fittings and partitions, he likened to the stalls in a cattle byre, and declared he had found a souterrain.

But the “destruction” of the roundhouse doesn’t appear to be 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 constructions.

“There’s no reason to believe these people were newcomers to the area,” said Martin.

“They possibly had connections to the original roundhouse builders and by reusing elements of that structure – something that had dominated the landscape for centuries – they were perhaps seeking to exploit its importance and mark their place in that landscape. In effect, they were adding their buildings to the broch, perhaps wanting to keep the connection to those who had gone before.

“They’re making a point of digging right into the remains of the roundhouse, with the later Iron Age buildings impinging into the fabric of their predecessor itself. It’s as if they’re making a point of digging into it and using the broch-like structure as part of their own.”

Four late Iron Age structures were constructed on top of the roundhouse remains – a domestic complex (Structure B), two metalworking buildings (Structures C and E), and a souterrain (Structure D).


An underground passage

The entrance to the underground passage. (Sigurd Towrie)

One of the most exciting examples of this reuse of roundhouse came to light this year.

Outside the entrance, the excavators have located a well-built, roofed, underground passage.

The three-metre long passage connects up to the reused broch entrance, essentially turning the latter into the chamber of an earth-house, in use during the later Iron Age, when the interior of the roundhouse had been filled in.

Just where the passage meets the reused roundhouse entrance, a set of paired stone uprights, embedded in the sides of the underground passage, represent a set of door checks, or jambs, showing that this passage was equipped, at one time, with a door that had to be crossed before entering the chamber.

Given the chronological gap that appears to exist between the end of the roundhouse and the beginning of the buildings that post-date the souterrain, Martin suspects that the earth-house dates somewhere in the region of AD300-500.

This passage awaits full excavation but already it has yielded a bone pommel, likely to have been part of the handle of an impressive sword.


Metalworking and ritual closure

One also can’t help but wonder whether we have something similar to Minehowe – an underground chamber surrounded by metalworking structures. Fine metalworking at the Cairns took place in Structure C, an oval-shaped building to the east of the roundhouse.

In use from around AD100-600, Structure C incorporated elements of the roundhouse into its design and has yielded a wealth of artefacts. As well as bronze fragments, moulds and other Iron Age metalworking detritus, a collection of iron objects were found clustered around the apparent metalworking focus of the building. One of these may be part of a “door-knob” spear butt mould, examples of which were also found at Minehowe.

“These finds are exciting but, as ever, leave us with more questions,” said Martin. “What was this item, and the other iron objects, doing on the floor of Structure C? They must have been left on the floor at the end of the use of the building, but why is a difficult question to answer.

“It may be that they were old objects gathered together to be melted down and remade into something else. Alternatively, they may have been deliberately left on the floor of the workshop building as part of a ritual act of closure. We’ve seen this previously, with a dozen finely-made and decorated long-handled combs deposited in a pot, again at the end of the use of the building.”

But Structure C was not restricted solely for metalworking. The heat from the forges also provided an area for the drying of grain – and outside, the excavators found the site of a peat stack that may have supplied the fuel for the fires.

And while fire was integral to this building’s use, it also seems to have played a major part to its “decommissioning”.

Evidence of a major blaze within the structure suggests that its roof may have been deliberately set alight, after the pot of decorated combs were deposited close to the entrance.


The ‘Cairns Character’

The "Cairns Character"

But perhaps the most intriguing example of a ritual closure artefact from the cairns was unearthed, last year, in a pit dug into the remains of the domestic building, Structure B.

While the national press was abuzz, last summer, over the discovery of the “Orkney Venus” at the Historic Scotland excavation at the Links of Noltland, Westray, down in South Ronaldsay the archaeologists had found their own “Cairns Character” – a tiny, beautifully carved, stone head.

Lying to the north and north-west of the main trench, the Structure B complex contains cellular, rectilinear and sub-circular building remnants, with many well-preserved hearths, stone fixtures and fittings, thresholds, wall piers and floors.

This complex, Martin explained, was undoubtedly domestic, and produced artefacts consistent with this – substantial amounts of pottery, stone tools, and an extensive animal bone assemblage.

The stone head had been carefully deposited in a pit, along with a number of other artefacts, presumably at the end of the site’s life. We can only guess as to the carving’s purpose – was it intended to portray a spirit or god, or was it merely a cherished possession?

Summing up the 2010 season, Martin explained: “One recurring aspect of this site is the fact that there’s a whole series of later features that have muddied the waters somewhat.

“On the one hand we’ve been able to piece together these really intimate details of life within these structures – the domestic artefacts, the metalworking etc, but at the same time the overall shape of some of the buildings remain obscure – obliterated through time and continual reuse.”

The excavation was supported by Orkney Islands Council, Orkney College UHI, the Scapa Flow Landscape Partnership, Orkney Research Centre for Archaeology (ORCA) Aberdeen University and Glasgow University. The team would also like to thank the South Ronaldsay community and landowner Charlie Nicholson.


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