Brochs: size of territory and location

In 1982 Noel Fojut published a paper entitled ‘Towards a geography of Shetland brochs’ in which he constructed a model of settlement location in relation to the physical environment. He calculated that the average distance to nearest neighbour was 2.787 kilometres (giving a figure of around 7 sq. km. for the average area of a broch territory). The result of mapping the brochs using this calculated average (fig.1) shows that, on the large scale, the brochs are far from being regularly spaced. The density is greatest at the southern end of the archipelago and so I have redrawn the map (fig.2) to show just this area and assuming that each broch territory is a square 1.5km x 1.5km. This seems to fit the data reasonably well, bearing in mind that the broch wouldn’t always be at the centre of its territory.

Fig.1 Shetland broch territories,                            Fig.2 South Shetland broch territories

assuming a diameter of 2.787km                           assuming a diameter 1.5km

Mapping the Caithness brochs using a figure of 1.5km for the diameter of the territory gives an interesting result (fig.3). There is evidently more clustering in this region, which may an indication of family or clan groupings that farmed the land in partnership. Another (strong) possibility is that not all of the brochs were in use at the same time.

   

Fig.3 Caithness broch territories, using a figure of 1.5km for the territory diameter

Fojut suggests two possibilities for the observed distribution in Shetland:

a)     brochs were located with regard to the siting of their neighbours

b)     brochs were located with regard to the physical environment

It has been remarked at various times that brochs form invisible chains across the landscape, presumably to allow rapid visual communication, for example in case of surprise attack. This concept arose when brochs were still thought of as Celtic watchtowers against Viking invasion. Fojut clearly demonstrates that such lines of communication do not exist in Shetland and goes on to say that brochs seem to be sited so that they have a good view of the immediate surroundings, with less regard paid to distant prospects.

So we can assume that, in the majority of cases, brochs were located with regard to the physical environment. Environmental quality depends on a number of factors such as soil quality, water supply and availability of building material. Proximity to the coast may also have been a factor in some regions. Fojut’s conclusion was that soil quality was the most influential factor, suggesting that it was only thriving agricultural communities that had the necessary wherewithal to erect these monuments. The rest of the population had to make do with their existing huts and duns.

There is a high degree of preference for coastal locations in Shetland, but this may be due simply to the lack of good agricultural land further inland. Broch density is just as high in parts of central Caithness as it is on the coast. Where brochs are located on the coast, they are often in cliff-top locations, without direct access to the sea.

We have seen that most broch communities existed in close proximity to agricultural land, but what of the location of the broch within that community? In many cases the site chosen was an elevated one, often on the side of a valley, and possibly at the border between the arable land and the rough pasture. It is likely that such a site would have been closer to suitable building material than one situated down in the valley. Defensibility was also important. Of 75 Shetland brochs, Fojut found that only 4 were not on good defensive sites.

What of the population associated with each broch? Fojut has calculated that for each of the twelve most southerly Shetland brochs, the associated land could have produced enough grain to feed a population well in excess of one hundred. Of course if much of the land was given over to grazing, the productivity would have been much less. Those communities with access to the sea would in general have needed less land than their inland neighbours. In general the rule seems to have been ‘a little arable, plenty of grazing and access to the shore’.

Reference

Noel Fojut, 'Towards a geography of Shetland brochs', Glasgow Archaeological Journal, 9 (1982) 38-59