Lewis, Loch Bhorgastail

This project aims to investigate a number of recent spectacular underwater discoveries from lochs in Lewis, Outer Hebrides. A programme of non-invasive geophysical (sidescan sonar, dual frequency single beam echosounder), drone and diver based survey was carried out between the 11th and 21st July 2016. Three lochs were chosen for study: Arnish, Bhorgastail (also known as Carloway) and Langabhat. The results from work at all three sites indicate that artificial islets were a feature of the landscape during the Neolithic.

NB 42301 30238 Geophysical, aerial and ground survey at Loch Arnish worked well, with excellent results from both the sidescan and echosounder systems allowing for the loch to be mapped. The extent of the rubble foundations can be seen and plotted, as too can the variable depth of the loch and associated sediments. The crannog is clearly multi-period, with Neolithic and later pottery recovered by Chris Murray (in previous years), and later modifications (iron rings set into the crannog walls) also visible. Diver based survey was challenging but possible, with poor visibility slowing work and reducing the area that could be examined. A single piece of prehistoric pottery was found on the loch bed.

NB 21148 40955 Survey work at Loch Bhorgastail mapped the loch and surrounding landscape. Diver based survey was highly successful with good visibility. This allowed for the identification of numerous Neolithic pottery fragments in association with the artificial islet. No material culture from later periods was encountered, indicating a Neolithic date as being highly likely. Diagnostic sherds were recovered and are currently with Dr Mike Copper for analysis.

NB 21684 43805 Survey work at Loch Langabhat mapped the loch bed and surrounding landscape. A significant amount of Neolithic pottery was found underwater, in association with the artificial islet through diver survey. No later material culture was identified, strongly indicating a Neolithic date for construction.

Archive: Stornoway Museum (intended)

Funder: British Academy, Leverhulme Trust, and Honor Frost Foundation

Fraser Sturt and Duncan Garrow – University of Reading

(Source: DES, Volume 18)

NB 21148 40955 Following underwater diver and geophysical surveys carried out in 2016, small-scale excavation and photogrammetric recording on the small artificial islet or crannog at Loch Bhorgastail was undertaken, 17–20 July 2017. Our aims were to establish a better understanding of the construction methods used in building the artificial islet, to establish the presence/absence of any buildings, to recover any archaeological material associated with the islet itself (in addition to the substantial quantities recovered previously from the loch bed around it), and to record the islet’s form both below and above water.

During the process of initial vegetation clearance towards the southern part of the islet, a suspected (and subsequently confirmed) otter ‘resting place’ was identified on the islet’s northern edge. At this point, all archaeological work ceased. Despite the fact that it was not possible to excavate, we were able to observe the islet’s form in substantially more detail than previously seen. The above-water area appeared to have been built as an outer ‘ring’ of stones which contained a lower-level internal ‘base’ or ‘floor’ (also made from stones). The stone base appeared to be overlain by dark brown, peaty soil deposits likely to relate to the islet’s Neolithic occupation phases. It was possible to complete the abovewater photogrammetric survey using a drone, adding to the underwater work already undertaken. In addition, two palaeoenvironmental cores were obtained from the loch bed to the E of the island. Substantial numbers of worked timbers, additional to those seen during previous work at the site, were also observed, suggesting a possibly extensive timber structure that survives underwater on the islet’s eastern side.

Archive: Museum nan Eilean, Stornoway (intended)

Funder: British Academy, Leverhulme Trust and Society of Antiquaries of London

Duncan Garrow – University of Reading

(Source: DES, Volume 18)