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DIARY

Week One (1st – 7th June)

Excavation site diary

Project team members Helen Bradley and Tom Dawson arrived in Shetland after a twelve-hour ferry crossing from Aberdeen. At the site, they saw a large turf-covered mound with one or two stone flags peeking tantalisingly through the grass cover. Beautiful sections of walling were exposed on the sea-facing side, giving them a glimpse of the complexity of the architecture below the turf. A pile of recently exposed burnt stones showed that erosion was still an ongoing problem.

The site before excavation

The site before excavation

The site had been partially excavated in 2000, and at the end of the dig, it had been backfilled with soil. This needed to be removed to allow the archaeology and reconstruction teams to start their work. In damp and grey conditions, four days of shovelling commenced. Local contractor Stewart Hunter assisted by expertly removing spoil from the site using a tracked mechanical digger fitted with a narrow bucket. This was filled directly by the digging team, using the bucket as if it were a large wheelbarrow.

The process was rather unusual from an archaeological point of view; the team used one of the detailed plans produced in 2000 to determine where to find key stones and sections of walling. Once located, Stewart was able to help carefully remove the backfilled soil from the cells and passageways.

Mark clearing soil from the top of one of the buried corridors

Mark clearing soil from the top of one of the buried corridors

Local volunteers Jim Grunberg, Mark Barry, Zoe Anderson, David Manson, and Barbara and Maurice Anderson helped dig, and they were soon able to see the site re-appear as they shovelled out the spoil. The big clear out was tough going but deeply rewarding; once revealed, it was apparent that the structures had fared well in the intervening eight years (with the exception of the section closest to the sea, which had witnessed further destruction). The floors had been protected by geotextile, a material that had been laid down at the close of the 2000 excavation in order that unexcavated parts of the site could easily be differentiated from the backfill.

Site with protective covers from previous excavation

The uncovered site covered with geotextile

Reconstruction site diary

The construction method at the site was to build the structures against a pre-existing mound of burnt stones. Rather than constructing a new mound to contain the structures, the project planning team decided to drill into an existing mound of bedrock at the reconstruction site beside the Heritage Centre. The local rock on Bressay is Old Red Sandstone, a soft sedimentary stone that breaks apart relatively easily, often into perfect slabs. In a similar fashion to the construction method at the original site, the dry-stone walls were to be revetted against the edge of the dug out area.

The mound beside the Heritage Centre before the reconstruction

The structures are irregular in shape, with curving walls and cells branching off two passageways. A detailed plan of the inner and outer edges of the walls needed to be produced and transferred to the reconstruction site to allow an appropriately-shaped hole to be dug into the rock. At the original site, the exposed structures were surveyed using an electronic theodolite or EDM (Electronic Distance Measurer). Survey flags were placed at key points around the site and the EDM recorded the position of each of these in relation to a series of fixed points established around the site. This produced a plan, accurate to within millimetres, of the outer faces of each of the walls. The instrument works by recording the vertical and horizontal angles from the instrument to the point to be surveyed. It also fires a laser at a hand-held prism set up over the point; the time taken for the laser to reflect back to the machine is used to determine the distance between the prism and the EDM.

Tom using the EDM

Tom using the EDM

After the site was surveyed, the EDM was taken to the reconstruction site so that the points noted could be marked out on the ground. Using the ‘stake out’ programme, Helen and Tom marked the relative position of each of the flags recorded during the original survey. Lines were then drawn on the ground to indicate the position of the outer walls in readiness for the mechanical excavator.

Helen marking out the position of the walls

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