Case Study: Clachtoll Broch

Susan Kruse 

Brochs are found in the Highlands, mainly on the east from Tain northwards, and also on the west coast including Skye. Many have been subjected to antiquarian investigation, usually focusing on the interior deposits. However, more recent work on their structural aspects by John Barber and Tanja Romankiewcz, a variety of recent excavations on Caithness brochs including at Thrumster (MHG2043) and Historic Assynt’s excavations at Clachtoll (MHG13002) in northwest Sutherland are starting to provide firm evidence for these structures which have long caught public imagination.

At Clachtoll, the walls fell down, which preserved a wide range of artefacts and information on the environment and subsistence. The good preservation has allowed sampling for dating and phasing. Multiple floor levels preserving organic materials were found. Objects are overwhelmingly domestic. Finds include steatite lamps or containers, spindle whorls (in all stages of production) and combs for textile production, and even a fragment of spun wool, bone pins and a cetacean bone pommel, a copper alloy ring-headed pin, and querns for grinding grain, and then later re-use as building materials. Finds in the intramural guard cell were particularly well preserved, and included partially articulated animal bone, ceramic sherds, worked wood fragments and sheet metal fragments, all interpreted as probable midden deposits rather than in situ artefacts. Unusually, iron survived at the site, and finds include axeheads, blades, socketed scythes, reaping hooks and pins. Interestingly there were few ceramics, and in a site with such good preservation one would expect to find them if they had been in use. The examples found fit best with the pottery tradition of the Hebrides, but it appears that the Clachtoll pottery was made on site. The copper alloy pin was made of leaded bronze, an important finding as previously this alloy was considered to have arrived with the Romans.

Three archaeologists excavating the interior of the broch.
Figure 1: Excavating the rubble layers in the interior of Clachtoll Broch ©AOC Archaeology Group
Figure 2: View of Clachtoll Broch entrance after excavation ©AOC Archaeology Group

The artefacts have been carefully mapped where they were found, and have been interpreted as showing discrete areas within the broch. For example, most metal objects came from the southeast area, suggesting that this may have functioned as a storage area for iron tools. In contrast, demonstrably personal objects including combs and pins, came from the western half of the broch, perhaps suggesting that this may have been an area more routinely occupied as a living space. The northeastern area was lacking in domestic finds, but a knocking stone was found and high concentrations of carbonised grain, suggesting this area was perhaps for cereal processing.

Muddy hand holding a recently excavated ring-headed pin.
Figure 3: A ring-headed pin was just one of several finds of personal objects from the western half of the broch interior ©AOC Archaeology Group

The activity at the broch for the most part dates to a short period, between 50BC and the very early years AD. The last major activity on site was a major fire inside the building, after which occupation ceased. This has provided good evidence for dating and analysis. A couple of radiocarbon dates suggest possible earlier use of the site, with the current remains being either a new building or rebuilding which erased earlier all occupation traces. Preliminary investigation at a few other sites in the landscape, including two promontory forts and a crannog, show activity contemporary with the broch, and interestingly a cessation of activity at about the same time as the broch. Further work in this landscape would be useful.

The excavations are important in providing detailed structural information about brochs, together with extraordinary preserved and well-dated artefactual and environmental evidence, including rare finds of iron objects. The good preservation has allowed analysis of residues in steatite vessels, wear analysis on bone weaving combs and other details rarely possible. It is one of the few Iron Age Scottish sites where the evidence allows one to assess interior house use.

The intent is to stabilise the broch now, a major undertaking which will present its own challenges, particularly for a multi-period site which had a major collapse.

Further information

Reports in Discovery and Excavation in Scotland 2017, 2018

Note: Much of this information is derived from talks given by Dr Graeme Cavers and Dr Andy Heald (AOC Archaeology Group) while post-excavation analysis was underway. The publication of the results of the excavation will provide further details.