EARLY IRON AGE CRANNOGS:
THE SWAP PROGRAMME IN GALLOWAY
In 2006, following the Edinburgh meeting of the Wetland Archaeology Research Programme (WARP), Historic Scotland commissioned a review of the archaeology of Scotland’s wetlands. The resulting report highlighted the international importance of settlement in Scotland’s lochs, bogs and mires, but also drew attention to how little was known about this aspect of the UK’s archaeological record. There are around 400 known crannogs, or artificial island settlements, in Scottish wetlands, yet they remain poorly understood in comparison to other site types.
Many of Scotland’s crannogs are known to date to the Iron Age, with a good proportion of those dated so far belonging to the mid-late first millennium BC. This is a problematic period in Scottish archaeology, since radiocarbon dating is inaccurate as a result of the flattened 14C calibration curve in the period 800-400 BC, often meaning that activity cannot be dated more closely than a century or two.
Wetland sites, however, often preserve structural timbers that can potentially be used to provide a dendrochronological date (derived from the alignment of tree-ring patterns with master sequences). Dendro is usually much more accurate than radiocarbon dating, and can often date the felling of a tree to a single calendar year. Crannogs, of course, are built predominantly in timber which is often preserved by wetland conditions, so the possibility existed to be able to be very precise with the date of occupation of these prehistoric settlements- something that has never been achieved in Scotland before.
Refining Chronological Resolution: a landscape approach
The breakthrough came at the crannog of Dorman’s Island, when the first prehistoric dendro date was obtained from split oak logs used as flooring on the island. This showed that that crannog was occupied between 153 and 121 BC and again in the sub-Roman period, but most crucially demonstrating that Galloway crannogs could be linked to Irish and northern English dendrochronological sequences.
Structure 1 at Cults Loch crannog
This new, fine-grained approach to early Iron Age settlement allowed, in turn, the possibility to explore the relationship between crannogs and their contemporary ‘dry land’ settlements. Taking a landscape-oriented approach, the SWAP programme investigated a cluster of Iron Age settlements around Cults Loch, Castle Kennedy in an attempt to understand how crannogs might relate to nearby enclosed settlements and forts.
The results were spectacular: the promontory crannog in the loch produced evidence for several buildings, centred on hearths and floored with exceptionally well-preserved plant litter and bracken. Beneath the floors, several objects had been placed, including a finely-carved ard (an early form of plough), a wooden vessel and a range of thin stave-like objects. It seems likely that these were placed in the foundations of the buildings as an act of offering or blessing for the house.
As hoped, it was possible to dendrochronologically date occupation of the Cults Loch crannog, showing that the houses had been built, used and abandoned over a relatively short period, perhaps no longer than two or three decades in the mid-5th century BC.
Alongside the work on the Cults crannog, excavations were carried out on a promontory fort on the opposite side of the loch and at a ditched and palisaded enclosure to the northeast. Although much less well preserved, these sites provided evidence for settlement and agriculture before, contemporary with and after the excavated crannog. The results included the first excavation of a souterrain in Galloway, and provided agricultural and domestic context of the early Iron Age landscape, of which the Cults crannog was a key part.
Modelling Iron Age Activity
Coupled with Bayesian statistical modelling of the radiocarbon determinations from the Cults investigations, it was possible to discuss the origins and development of settlement in the vicinity of Cults Loch in a far more nuanced way than is usually possible in Scotland. The project was able to shed light on the duration and nature of settlement on the crannog, providing fodder for the debate on the reasons for building on lochs in the Iron Age. The data from Cults Loch provides a glimpse of farming life in the mid-first millennium BC, with the 5th century BC increasingly coming to be viewed as a period of instability and change in the landscape, when many wetland areas may have been settled for the first time.
These themes, and the wider context of lake settlement in Europe, were the topic of a seminar session co-convened by AOC’s Anne Crone and Graeme Cavers at the meeting of the European Association of Archaeologists in Glasgow, in September 2015.
A New Direction: Black Loch of Myrton
The hypotheses and models developed through the Cults Landscape Project were given the opportunity for test in 2013, when AOC were given funding for excavations at the newly-located wetland settlement at Black Loch of Myrton, near Monreith. Discovered by the farmer during drainage operations, excavations at Black Loch in 2013 and 2015 found evidence for a site type that is so far unique in Scottish archaeology, a wetland village, perhaps akin to the famous Glastonbury and Meare villages.
The buildings were spectacularly well preserved, with the structural posts, flooring material and monumental stone hearths all surviving in excellent condition. Unlike a true crannog, the Black Loch village was built directly onto wet and boggy ground (rather than in open water on an artificial platform) meaning that the footprints of the buildings were clearly identifiable.
The houses were probably occupied repeatedly, perhaps seasonally, with new floors and hearths built for each occupation, meaning that sequences of activity could be identified within each house. The sinking of the stone hearths into the peat bog meant that each one was built on top of its predecessor, resulting in a ‘hearth mound’ that encases the multiple refurbishment episodes of each house. Artefacts have been limited in number, but have included querns and other stone tools, and the iron share from an ard, perhaps similar to the one found at Cults Loch.
Post-excavation analysis of the samples from the Black Loch site is on-going, but initial work has demonstrated that the occupation deposits are very rich, with insect remains indicating the stabling of animals and some evidence for differentiation of activities within the houses.
Radiocarbon dating has indicated that the Black Loch settlement was probably first built in the same mid-first millennium BC horizon as the Cults Loch crannog. With evidence for at least eight structures at the site, Black Loch could provide key evidence for testing our models of prehistoric settlement and society in Southern Scotland, with implications for understanding the Iron Age more generally.
Structure 2 at Black Loch, showing one of the lower, clay-lined hearths surrounded by flooring and structural timbers
The SWAP Programme is funded by Historic Environment Scotland.
A monograph report on the Cults Landscape Project is now complete and in the final stages of preparation for publication.
The excavations at Dorman’s Island crannog are reported in the Journal Of Wetland Archaeology, volume 10, 2011.
Many of the themes of the SWAP programme are discussed in papers by Anne Crone and Graeme Cavers in Lake Dwellings After Munro: read the volume online for free, here.