Unravelling centuries of Iron Age activity

Archaeological work has resumed on an Iron Age site in South Ronaldsay – once again attempting to unravel a complex series of buildings clustered around the site of a massive broch-like building.

The excavation at the Cairns, led by Orkney College lecturer Martin Carruthers, is the latest in a series on the site. This year, over 20 excavators have been paintstakingly sampling, recording and working their way through centuries of archaeological remains.

The first building on the site, overlooking the Bay of Windwick, was a massive broch-like roundhouse – with five-metre thick walls forming a structure with an exterior diameter of 22 metres. From pottery remains found on site, it is estimated that this structure dated from around 500BC.

After the roundhouse fell out of use, a series of later buildings were constructed – the builders deliberating “biting” into the walls of the disused broch.

Martin explained: “This site is particularly unusual in that they’re making a point of digging right into the remains of the central structure. Normally, these later Iron Age reutilisations of a site are confined to the extra-mural buildings – those clustered around the broch – and in the centre of the broch itself.

Picture: Sigurd Towrie“But what we’ve got here is that the later Iron Age structures are actually impinging into the fabric of the broch itself. It’s as if they’re making a point of digging into it – they were using the broch-like structure as part of their own. As an analogy, if we look at the broch as being something like a big apple, what we’ve got is a situation where the later builders were taking these bites out of it.”

As a result, the excavators are faced with a massive archaeological jigsaw puzzle, with a huge sequence of buildings on site, representing centuries of use.

This is forcing them to work down through the later layers of archaeology to build up a picture of the site’s use – a process that Martin described as “something of a double-edged sword”.

The excavators can’t get to the bottom of the actual roundhouse structure itself without first going through the accumulated layers of archaeology on top.

The downside is that this inevitably takes time but, on a positive note, it provides the experts with information that wouldn’t otherwise be available.

For example, working down through the later buildings, the team has uncovered the remains of a fireplace, built into a later structure overlaying the remains of the original roundhouse wall.

Samples taken from this fireplace will provide the archaeologists with a date that will allow them to pinpoint the time when the roundhouse fell out of use – something that would not have been possible had the structure been undisturbed, or standing on its own.

“As we work down through the layers of archaeology, we’re gradually piecing together picture of how all these later building relate to each other, and the roundhouse at the centre of the site,” Martin added.

One of the most exciting finds of the 2009 excavation is the remains of the staircase that ran between the roundhouse’s external and internal walls.

Picture: Sigurd TowrieThe intra-mural staircase – a feature typical in brochs – is, said Martin, pointing to a more classical definition of a broch, but due to the dimensions of the structure, he remains of the opinion that it was not as tall as brochs such as Gurness, and Mousa, in Shetland.

Martin said: “We’ve got these incredible, five metre walls, with an external diameter of 21.5 metres, forming an inner chamber 11.3 metres in diameter. This makes it bigger than both the brochs at Gurness and Midhowe.

“But, although the internal space was much bigger than Gurness, the width of its walls makes me think it might not have been very high. For comparison, it was perhaps as high as the ruins of Gurness stand today.”

This year, as well as confirming that, as suspected, the roundhouse entrance was to the south-east of the structure – and had been deliberately blocked up – further evidence of metalworking has been found in the remains of the later building, known as Structure C. In addition, a pit to the north of the site has been producing a wealth of animal bones, as well as red deer antler fragments.

The antlers tie in with the previous excavations, which uncovered copious quantities of red deer remains. From these, it appears that the inhabitants were actively managing the animals – culling and “harvesting” them for their antlers and presumably food.

With a massive external diameter of 22 metres, 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.

The excavation was supported by Orkney Islands Council, Orkney College, Cardiff University, the Scapa Flow Landscape Partnership and the Orkney Research Centre for Archaeology (ORCA). The excavators would also like to thank landowner Charlie Nicholson.

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