Loch Glashan Logboat
Logboat, with the Glashan dam in the background. Image Copyright AOC Archaeology Group.
The lowering of the water level in Loch Glashan this summer exposed the remnants of a logboat on the shore just to the south of the dam. Only a small fragment of the logboat remained, and this was in a very decayed condition. Its position high above the original waterline of the loch indicated that it had moved from its original resting-place, probably some time since 1960 when the dam was built. These considerations, its severely compromised condition and position, prompted the decision that the logboat should be fully recorded and also sampled for radiocarbon-dating, but that it should then be re-submerged in the loch, rather than being lifted and conserved. This work was undertaken by staff from AOC Archaeology Group, and was commissioned by the Forestry Commission Scotland, who own the land.
Upper surface of the logboat. Image Copyright AOC Archaeology Group.
The surviving fragment is just 2.7 m in length and 0.48 m at its widest point. In cross-section, all that survived was a hollowed-out chord, 0.15 m at its thickest. The upper surface was completely eroded, although a strip along one edge might be a remnant of the original surface. There wasnothing to indicate whether it has been deliberately hollowed out, or whether the hollow is simply due to decay. The lower surface was much better preserved. The curved surface of the heartwood/sapwood boundary survived over much of the surface, although it was eroded at both ends. Scattered along this surface were clusters of shallow axemarks, some of which only became visible in low late afternoon light. They were mostly crescent-shaped, but many were very slight depressions, similar to a finger nail in size and shape. It seems most likely that these marks were incurred while stripping off the sapwood, the axe only glancing off the heartwood.
Shallow axemarks visible on lower surface of logboat. Image Copyright AOC Archaeology Group.
There were two branch junctions protruding from the log. One had been cut off long before the tree had been felled, the cambium having grown over the scar. The other branch junction had also grown over, but it projected some 70 mm from the heartwood/sapwood surface. It seems unlikely that a finished logboat would have been left with a branch projecting so far out of its hull, so it is possible that this is an unfinished example. The toolmarks clearly indicate that the log was being prepared for some function, so perhaps it had been left in the loch to prevent drying out before it was finished.
The logboat has been fashioned from a log of oak (Quercus sp.). Its dendrochronological potential was considered but there would not have been a sufficiently long ring-pattern to make analysis viable, particularly for a single sample; with a growth rate of between 6-7 growth rings per cm there was an estimated 90 - 105 growth rings present, so a splinter from the heartwood-sapwood boundary was removed and submitted for radiocarbon-dating. This has produced a date of 1720 +/- 25 BP (SUERC 36708), which calibrates to 250 - 392 cal AD.
This date is indistinguishable from the earliest group of radiocarbon dates obtained from the nearby crannog, which suggested building activity and occupation on the crannog sometime in the 2nd to 4th centuries AD. The radiocarbon date from the unfinished logboat lends credence to this early phase of activity on the crannog, one which probably saw the initial construction of the crannog. The manufacture of the logboat might have been part of the preparations for living and working out on the water.
The logboat is probably that observed by Fairhurst (1969, 47) during his excavations of the medieval settlement on the natural island in the loch, and recorded as WoSAS Pin 4642. It was found between the island and the shore and was left in situ at the time; its current position just immediately inshore of its known location in 1961 suggests that it has been moved directly inshore by wave and water action.