Southwest Scotland crannog survey

Ultimately through a long-term monitoring programme we hope to identify the mechanisms and causes of organic decay on crannogs throughout the South West so that effective preservation and management strategies can be implemented.

While 'packwerk' mounds of peat, brushwood and timber undoubtedly exist (such as at Buiston, Barlockhart, Milton Loch 1 and the Black Loch of Sanqhuar) there are also sites which feature a substantial stone element in their construction (for example at Dorman's Island in Whitefield Loch, Heron Isle in Black Loch, Cults Loch 1 and the crannog in Barean Loch) or that appear to be completely constructed out of stone with a stone superstructure on top (Rough Island in Loch Urr).

The artificial island in Loch Arthur (see Loch Arthur project) consists of two mounds of different material, the upper mound (the island) being built primarily of large boulders within a well developed soil, and the lower submerged mound of timber, brushwood and some smaller stones (Henderson et al. 2003; 2006; Henderson 2007).

Potential free-standing pile forms also exist. Survey of the submerged crannog in Barhapple Loch revealed a sub-rectangular plan of 144 vertical piles and 31 horizontal timbers (mainly oak with some alder) sitting directly in soft loch silts in a water depth of c.0.5 metres. The lack of any mound structure or boulder element to the site coupled with the dense distribution of vertical timbers may indicate that Barhapple was initially a free-standing structure that was later subject to the apparently in-situ occupation levels recorded by Munro in 1882.

At the White Loch of Myrton the crannog appears as a stone and timber mound with a dense concentration of over 100 vertical piles in an area some 20 metres by 40 metres occurring around the north-eastern margins of the site (Henderson et al. 2003, fig. 7, 93-94). The piles varied greatly in diameter from 0.1 metres to 0.4 metres and appeared to be regularly spaced about 1 metre apart. Most of the piles have decayed down to loch bed level although some still sit proud of the loch bed by about 0.2 metres. Soft silts surrounding the site and zero visibility conditions underwater made further examination of this site difficult but two piles, both with axe sharpened points, were sampled and identified as ash.

Although only traceable around the north-eastern margins of the main mound because the western and southern sides are shallower and choked with thick reeds, the location and spacing of the traceable piles suggest they were originally inserted into the loch bed in a concentric halo around the stone mound. They may therefore reflect the remains of either a site pre-dating the stone mound or of a free-standing timber superstructure contemporary with activity on the main mound.

The findings of the SWCS challenge simplistic definitions of crannog form and question the relevance of previously held type boundaries. Many of the sites in the South West which feature substantial stone elements are difficult to separate on constructional grounds from the boulder mound sites of the Scottish Highlands.

The perceived differences between the Highland and South West sites may be more attributable to the lack of underwater survey carried out nationally as many of the key identifiable characteristics of sites noted during the SWCS can only be seen underwater.

Previous surveys in the South West have been land based and have focused on the examination of drained sites. As a result the impression has been created in the literature that South Western sites are mounds of peat, timber and brushwood. In fact the occurrence of peat on sites may simply be due to the circumstances of preservation as brushwood and plant matter will survive intact in submerged contexts but such deposits are more likely to decay leading to the formation of peat on drained and periodically flooded sites.

The perceived differences between Highland and South Western sites may have more to do with the widespread drainage and improvement operations in the latter area than any significant cultural structural or chronological variation. Equally the more widespread occurrence of exposed organics and structural timber on submerged sites in the South West may be attributable to the smaller size and less active tidal regimes of those lochs compared to the much larger and more turbulent Highland lochs.