A unique glimpse into the Iron-Age

13 mins read

Excavating Clachtoll Broch

A decade of investigations at Clachtoll Broch, Ayssnt, has given vivid insights into the life and dramatic end of an Iron Age community in highland Scotland. CREDIT: Forge

Two thousand years ago, the Iron Age inhabitants of a highland broch fled as their home burned around them. The wreckage of this destruction sealed a vivid time capsule of their lives that remained undisturbed until the present day. What have recent excavations revealed? Mandy Haggith reports.

Imagine a catastrophic fire in a residential tower-building. People flee for their lives, abandoning the meal they were preparing, half-cooked. All their personal possessions, whether neatly tidied away or strewn on the living-room floor, go up in flames, leaving just a litter of scorched materials among rubble and devastation. After the tragedy, the site remains as a relic and reminder. Now imagine, 2,000 years later, the people who now live where the tower once stood, curious about what life was like for those poor tower-dwellers, pick through the wreckage with the help of a team of archaeologists to find out more about their prehistoric predecessors. Over the past decade, in a small community in the north-west highlands of Scotland, this is precisely what has played out.

Brochs are unique to Scotland, and their purpose has long been debated. Were these towers domestic, military, or ceremonial places? CREDIT: AOC Archaeology

Sometime around AD 50, Clachtoll broch – a 14m-tall (40ft) double-walled tower – burned down and partially collapsed in on itself. Its interior has been effectively untouched ever since, but, with the sea encroaching, the ruin has been becoming increasingly fragile and dangerous to visitors – and so, over the last ten years, a local community organisation called Historic Assynt has organised a project to conserve and consolidate the monument. This has enabled excavations (carried out with AOC Archaeology) that have uncovered a unique collection of artefacts from the broch’s previously undisturbed floor, giving a fascinating insight into Iron Age life. Alongside these digs, experimental archaeology has also explored how local materials including clay, wood, and wool were used by the broch inhabitants; these investigations, together with Iron Age-style feasts, have given local people a genuine taste of life in the tower. So, what did we find out?


A preserved ear of barley – one of many exceptionally well-preserved organic finds from the site, and a reflection of the main cereal crop cultivated by the broch community. CREDIT: AOC Archaeology

As the project’s excavations removed hundreds of tonnes of rubble from inside the broch, a diverse assemblage of objects was revealed, eloquently demonstrating that, around the time of the Roman conquest of southern Britain, the Clachtoll community had been part of a sophisticated maritime culture stretching up to the Northern Isles and out to the Hebrides. The objects only reflect a brief window of time, however – something unusual for a broch site, most of which were occupied for long periods, and which were often reconfigured by subsequent generations, meaning that many traces of earlier Iron Age activities were overwritten by later inhabitants. By contrast, Clachtoll lacks the accumulated detritus of centuries. Instead, the rubble from its destruction sealed an unadulterated time capsule from the site’s final occupation around 2,000 years ago.

Among these finds was a wealth of organic materials – charcoal, cereal grains, animal bone – that have since been radiocarbon dated. The earliest dates that these samples yielded are around 400 BC: although mixed with deposits of a later date, they indicate activity at the Clachtoll broch in the early Iron Age. Might they represent the earliest phase of the broch’s existence, or a previous building which had the same large circular footprint? It is a tantalising thought, and one that I have explored – in fictionalised form – in my novels (see ‘Source’ below). Assynt lies on one of the lines of latitude visited by the intrepid Greek explorer Pytheas of Massalia, who made a great journey from the Mediterranean to the far north in 320 BC, and who took sun declination measurements in several places where he made landfall. Could these locations have included Clachtoll, and, if so, might there have been a large circular structure for him to visit?

Rubble from the Clachtoll site’s destruction has sealed an untouched time capsule reflecting the final phase of its occupation. This has yielded a wealth of finds, including objects giving an insight into the community’s diet – such as this quern stone, used for grinding flour. CREDIT: AOC Archaeology

The vast bulk of evidence for occupation at the broch, though, comes from almost 300 years later, with almost all of the radiocarbon dates from the excavation falling between 50 BC and AD 50, after which the broch burned down. The significance of this relatively short final episode in the site’s life was highlighted by Graeme Cavers from AOC Archaeology:

What is impressive about this site is that it shows us a relatively short period of occupation, which came to an end so abruptly, and what was left has been untouched ever since, so the floor deposits were pristine. It therefore gives us a strong insight into life in that period. Of course, there is still a lot we don’t know, and we’ll never be able to be certain when this particular broch was built or why it burned down, but its contents add immensely to what we know about life in the north of Scotland in the Iron Age.

This boulder (shown under excavation by AOC Archaeology) was a ‘knocking stone’, used in threshing corn. CREDIT: AOC Archaeology


But while the broch’s floor may be ‘pristine’ from the point of view of being undisturbed in the intervening two millennia, analysis of its make-up revealed that, as a living space, the tower was absolutely filthy. This points to the broch being someone’s home, not a semi-military or ceremonial structure as is sometimes suggested for these towers, as the floor deposits were rich in the remains of species indicating domestic life, such as fleas, bed bugs, and other beetles associated with resident humans, along with plenty of rodents and a litter of animal and fish bones and other food waste.

An unusual number of iron tools have been recovered from the broch, including reaping hooks – shown being conserved. CREDIT: AOC Archaeology

Adding to this rather unhygienic picture, there also appear to have been animal carcasses buried in the layers of peat, sand, and ash making up the floor. The archaeological team is still trying to interpret the semi-articulated bones of two sheep or goats, one of which had been placed close to the hearth: it seems that the animals had been skinned, but not butchered for eating. It is not unusual to find evidence of ceremonial burials underneath Iron Age structures, so one possible interpretation is that the animals represent some kind of offering made at the time of reoccupation of the broch, perhaps when it was rebuilt. (Analysis of its walls suggest that the structure suffered some form of collapse and was reconstructed shortly before the final phase of its use.) For now, however, their purpose remains speculative.

A large iron sickle, more like a scythe, recovered from the broch. CREDIT: AOC Archaeology

Meanwhile, a wide scatter of more-conventional animal remains shed vivid light on the diets of the broch inhabitants. Sheep/goats, deer, and cattle dominate this picture, while pigs are present in much-less-substantial numbers. Cattle were also kept for their milk: residue identified on pots and other vessels indicates that they had once contained dairy products, as well as meat fat and vegetables. Other residue includes beeswax, perhaps used in ointments, raising speculation about beekeeping at the site.

Alongside meat, grain was another important food. Large quantities of cereal caryopses have been found, identified as six-row hulled barley (Hordeum vulgare L), along with chaff fragments and weed seeds which were all burnt in situ. While some wheat, oats, emmer, and flax have also been identified, six-row hulled barley was the chief cereal species, and the grain was both processed and stored within the broch, with what appears to be a sheaf of unprocessed ears of grain placed in one of the chambers by the entrance and strong evidence of milling taking place within the structure.

In the north-east part of the broch’s interior, a large igneous boulder had been set into flagstones that were roughly laid over a spread of compact brown-orange clay. This boulder was a mortar or ‘knocking stone’, with a central V-shaped hole about 25cm deep, like an upturned witch’s hat. It would have been used for threshing: the ears of wheat or barley were placed into the hollow and pounded to remove their tough outer husks. This particular knocking stone was found to be full of carbonised barley, so it is highly likely that it was actually in use when the broch was destroyed. Several rotary querns – used for grinding grain for flour – were found too, together with what is thought to be the iron spindle from one of them. This latter item was a rare find, as metal is rarely preserved from such sites, but it was not alone: the team also discovered a cluster of reaping hooks, which appear to have been stored together, completing the picture and suggesting a harvest successfully brought in for the winter.

The discovery of a pot sherd decorated with a round indentation, and a round-headed pin that matches the shape, vividly evokes the work of the potter who made it. CREDIT: AOC Archaeology


In fact, a considerable amount of iron tools have been preserved at Clachtoll broch. Graeme Cavers describes them:

We have quite an extensive collection of iron objects, amounting to almost a full toolkit. As well as the reaping hooks, we have a substantial sickle, more like a scythe, plus a spade shoe, a couple of axes, an adze, some sharp blades, and even what looks very like a bucket handle.

The remarkable preservation of such a collection is presumably due to oxidation being limited by a coating of ash from the fire, and a good seal under the rubble.

By contrast, pottery finds were relatively scarce: around 200 sherds were recovered from the broch, far fewer than would normally be expected for such towers, where occupation would have continued for hundreds of years. ‘What is interesting’, Graeme comments, ‘is that, because we have a short occupation period, this gives us a realistic snapshot of what kind and volume of pottery would have been in use at any time.’

One of ten stone vessels from the site, of a type usually associated with lamps, although traces of food residue hint at another function. CREDIT: AOC Archaeology

These sherds come from probably fewer than 20 vessels, and the decoration on them is similar to that found in the Outer Hebrides – not surprisingly, given that Lewis lies in full view less than 40 miles across the Minch. Experimental archaeology with local potters, using local clay fired in a pit kiln, has shown exactly how these pots could have been produced – it is hoped that ongoing chemical analysis will confirm that the pots were made of Clachtoll clay, which is still used by local ceramicists for pottery and glazing today. The likelihood of the pottery being of local origin is made much stronger by the delightful discovery of a sherd decorated with a round indentation, plus a bronze round-headed pin that matches it perfectly. Finds like this make it easy to conjure an Iron Age potter among the broch’s inhabitants.

As well as pottery, there was clearly creative stone-working going on in the building, with a large assemblage of what were initially described as ‘steatite lamps’ and ‘spindle whorls’. Ten stone vessels of a type traditionally interpreted as lamps were found, and they take several different forms, some with handles, some without, and with differently sized bowls and styles of decoration. Analysis by Dr Julie Dunne of the Organic Geochemistry Unit at the University of Bristol identified food residue on some, though, suggesting that this traditional identification may not be correct. Chemical analysis shows that they are not of the same steatite stone found in the Northern Isles and, as a similar stone is found only a couple of miles south of Clachtoll, they are probably made of local material.

Some 34 small, round stones – perhaps spindle whorls used in spinning wool, or weights for fishing nets – have been recovered during the excavations. CREDIT: AOC Archaeology

The assemblage of ‘spindle whorls’ is even bigger: 34 small round stones with holes carved in them (or under construction) were found scattered around the broch. They are decorated with a range of different markings, tempting speculation that these may indicate some kind of symbol system. Although some of them would most likely have been used for spinning wool (and a marvellously preserved piece of spun wool-twine turned up in a chamber between the walls as if to prove this), given the broch’s location on the shore of the Minch, it is more than likely that some of them, perhaps many of them, were weights for fishing lines or nets.

The influence of the sea must be taken into account in interpreting the finds, as it is clear that the broch’s inhabitants were part of a maritime society. The distribution of brochs across the north of Scotland, through the Hebrides and Northern Isles, demonstrates the similarity and cohesion of material culture that could only come about through the use of the sea as a highway. Indeed, this is exactly how it has been used up until very recent times, so it is unavoidable that we should look at the assemblage from a nautical perspective.

The broch inhabitants made full use of their coastal location to supply the community with food; fish bones and shellfish were prevalent among finds. CREDIT: AOC Archaeology


A strong clue that the broch people had boats is their dependence on the sea for food. Among the food waste in the floor were a lot of fish bones, mostly marine species such as saithe and pollock, as well as shellfish that could have been gathered from the shore. Interestingly, there are no fish skulls. Were the fish brought in as fillets, due to a cultural practice of depositing fish heads in the sea, perhaps, or were the heads just fed to the dogs? Sea-mammal bones form another important part of the assemblage, with whalebone (found both in unshaped chunks and made into tools) and seal bone (much of it scorched). While the seals may have been hunted, it is more likely that the whalebone would have been scavenged from washed-up or beached carcasses.

Driftwood would have been an important product of the sea, too. The broch finds include some pieces of substantial larch timber infested with shipworm, indicating that they had been afloat for a long period; they may have originated in Canada. Other tree-remains reinforce suggestions of a seafaring community: while the wood assemblage includes expected local species, such as a bowl rough-out made from alder, and the remains of objects made of oak, birch, and hazel (interestingly, no willow), there is also a considerable quantity of Scots pine, including carefully shaped square pins, a spatula, and a lot of splinters, which may well have been used as tapers for lighting lamps or, indeed, used as candles. (The tradition of using resin-rich pine tapers, or ‘rosety roots’, for lighting has carried on in Scotland until recently.) Although Scots pine is widespread in mainland Scotland, though, Assynt lies north of its present core area, and its presence here in the Iron Age is uncertain. If, as now, the nearest Scots pine trees were in Wester Ross, this would suggest sea-based, if relatively local, trading.

One of the site’s well-preserved organic finds: a bone comb. CREDIT: AOC Archaeology

The wood remains have also helped the archaeologists to piece together the story of the broch’s dramatic collapse. In the initial excavation, hazel roundwood was found on the scarcement ledge where the first upper-level flooring of the broch would have been supported. This has provided fertile ground for discussion and experimentation about the broch’s interior appearance. Gordon Sleight, project leader for Historic Assynt, said:

There have long been disputes among archaeologists about how the upper floors of brochs were built and what they were like. Standard illustrations tend to show nice level floors made of substantial timbers reaching across the whole interior. Charcoal remains and other findings at Clachtoll, however, point to lightweight galleries made from wattle panels.

In order to determine whether this was feasible, Historic Assynt and AOC carried out some innovative archaeological experiments by building a section of mock brochwall, with scarcement ledges for two levels of galleries, making appropriately sized and shaped wattle panels, fitting them, and then loading them with considerable weights. They proved remarkably strong, especially when fitted in a double layer. After allowing the panels to dry out fully, and placing replicas on them of some of the pottery found in the excavation, a small fire was lit beneath them. Within seven minutes, the first-floor panels were ablaze, and two minutes later the upper level was too. Gordon Sleight said: ‘No wonder the excavations at the broch suggested that, on the day of the final fire, the folk inside dropped everything and got out as quickly as they possibly could.’

A piece of spun cord recovered from the broch. CREDIT: AOC Archaeology

All in all, the remains that the broch community left as they fled the building 2,000-odd years ago have given us a fascinating insight into a domestic life that had some elements that would be distasteful to us now (not least the apparent poor hygiene) but also many aspects – food and crafts – that are similar to today. Gordon Sleight said:

The most interesting result of the excavation is the vivid picture it gives us of life in the broch in that 100 years. It is intriguing that there is a strong correlation between life then and now. The artefacts show livelihoods that are not so dissimilar to those in Assynt today – whether that’s fishing, crofting, pottery, or craftwork with wood and wool.

Thanks to engagement in the broch project by hundreds of local people and visitors, including all of the local schools, the current generation of Assynt inhabitants now has a tangible and enthralling connection with the tower-dwellers of 2,000 years ago. Charlotte Douglas of AOC said:

Fifty-five volunteers contributed over 2,000 person hours to the excavations, shifting vast amounts of stone and digging in all weathers. It truly was a team effort, just as the construction of the broch must have been many centuries ago.


The archaeology project was organised by Historic Assynt, a local community organisation. Fundraising was carried out with the assistance of the Scottish Wildlife Trust, as part of the Coigach & Assynt Living Landscape Partnership, of which it is the lead partner. Funding was provided thanks to players of the National Lottery through the National Lottery Heritage Fund, Historic Environment Scotland, SSE’s Sustainable Development Fund, the Pilgrim Trust, Robert Kiln Trust, Highland Council via Landfill Fund, and individual donors.


Mandy Haggith is a writer based in Assynt, and was the broch project liaison officer for Historic Assynt. Her latest books include a trilogy of novels inspired by Clachtoll broch, The Stone Stories (comprising The Walrus Mutterer, The Amber Seeker, and The Lyre Dancers).

This article appeared in CA 367. Read more features in the magazine. Click here to subscribe

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