Underwater Archaeology

Date 13 August 2017 - 25 August 2017

Event ID 1040986

Category Recording

Type Underwater Archaeology

Permalink http://canmore.org.uk/event/1040986

NN 6744 3623 (NN63NE 19) This work, undertaken 13–25 August 2017, formed part of the Living on Water investigation of Early Iron Age crannog-dwellers in Loch Tay. The project is excavating a range of crannogs with known EIA phases to collect structural timber samples for dendrochronology and wiggle-match 14C dating.

Dall Bay South crannog had two 14C samples return Early Iron Age dates, one of which came from an exposed pile near the base of the mound and the other from an exposed timber on top of the mound. These two areas were targeted for the 2017 field season.

Two 2 x 2m trenches were opened over each area. The trenches were drawn by hand, photogrammetrically recorded and surveyed by dGPS. Trench 1 was located on the E side of the crannog mound, near where the rubble capping of the crannog meets the natural soft loch bed sediment, while Trench 2 was located on the top of the crannog mound towards the E side of the site.

In Trench 1, at the bottom of the mound, 22 timber features were identified, the majority upright piles. The timber features emerged through a layer of organic material, mostly ash, bracken, sedge and fragments of charred wood remains. This organic layer was under a layer of fine sand gravel, which in turn was below a layer of cobbles and boulders (the exposed rubble capping of the crannog). Three of the wood uprights were of much greater diameter than the rest and these are likely oak, compared to alder for the rest. Ten alder piles were sampled.

Trench 2 revealed a virtually identical stratigraphic sequence with large cobbles and boulders on top, with finer material below. This sat above the structural timbers. In Trench 2 however, the timbers were predominantly horizontally laid, but again mostly alder. The horizontal timbers formed at least four (but up to as many six) layers, perpendicular to each other. Four upright stakes were also identified, running in a near straight line across the trench.

Amongst the horizontal timbers, deposits of ash, charcoal, bracken and sedges were identified. Eight horizontal timbers were sampled in this trench. No artefacts were recovered from either trench.

Timber sampling was carried out by sawing the top off vertical timbers, and slices requiring two cuts were used on horizontal timbers where necessary. These samples will be subject to dendrochronological analysis and wiggle-match 14C dating over the course of the project.

Archive: NRHE and ADS (intended)

Funder: Historic Environment Scotland

Michael J Stratigos – Scottish Univerisities Environmental Research Centre

(Source: DES, Volume 18)