EHG4010 - Trial trenching - new Thurso Substation site

A trial trenching evaluation was undertaken in 2012 by Highland Archaeology Services at the site of a proposed electricity substation, circa 1 mile south-southwest of Thurso. Fifty-one trenches were opened and in addition the excavation of 35 engineering test pits and 6 boreholes were observed. The Highland Council Historic Environment Team originally asked for a 10% sample to be taken by trial trenching, but after discussion it was agreed that a 5 % sample would be adequate to evaluate the site. The final area opened, excluding the SSE test pits and boreholes, was 5,051 sq.m. The following mechanically excavated trial trenches were opened: 8 square trenches each measuring 10m x 10m, 42 bucket width trenches, nominally 2m wide and 50m long, covered 4, 200 sq m. Trench 1, a bucket width trench, had to be reduced in length to 25m nominally 2m wide and 25 m long, to cover 50 sq m. 8 square trenches, to cover 800 sq m.: providing a sample area of 5, 050 sq m. No archaeological features were encountered within the trenches, and no evidence was found of a farmstead previously recorded within the developable area. However a previously unrecorded linear bank and ditch and a round cairn were noted within the site, and at the Highland Council’s request a limited exploratory excavation was conducted to try to clarify their nature and extent. Both appeared to be constructed features: the bank may have been a boundary marker, while the cairn had a form consistent with a Middle to Late Bronze Age date, although no supporting archaeological evidence was found during this limited intervention. If the cairn is to be unavoidably disturbed by the substation development, archaeological excavation, recording and removal of this feature was recommended before site stripping takes place. Otherwise no further archaeological fieldwork was proposed. <1>