EHG6298 - Watching brief - GI test pits, proposed new Edinbane Substation, Balmeanach

An archaeological watching brief was undertaken by AOC Archaeology Group in 2024 in respect to the proposed development of a new substation at Edinbane Substation, near Balmeanach, Isle of Skye. The proposed development site was located approximately 3.2km northeast of Balmeanach and 6.9km south of Edinbane village. The work on nine Geotechnical test pits across the western part of the site was carried out in advance of a proposed main phase of archaeological evaluation (see EHG6299). This highlighted the possibility of deep peat deposits around the site and allowed test pits to be microsited away from known historic structures. These test pits revealed the varied character of peat deposits across the western side of the site. <1> Palaeoenvironmental assessment was subsequently carried out on samples obtained from the site and from those from a subsequent phase of palaeo-environmental coring (see EHG6481). The deposit sequence recorded across the site included tertiary bedrock of the Skye Lava Group Basalt and Microgabbro forming c. 66 to 23 million years ago with a surface elevation at 71.55 to 85.93 m OD, rising in elevation towards the north of the Site. Pleistocene till forming c. 116,000 to 11,800 years ago, comprising a stiff to firm gravelly and sandy clay which is reddish brown to bluish grey in colour, is encountered between 66.41 to 93.99 m OD, declining from north to south. The till is overlain with herbaceous to woody peat with a thickness up to 5.87 m and a surface elevation between 68.46 and 94.24 m OD. Palaeo-environmental assessment of the peat provided a long-term record of landscape evolution, vegetation succession, and peatland succession dating from the Early Mesolithic / Early Holocene. No direct evidence of human activity was recorded. Archaeology, comprising structural remains and a clearance cairn, was recorded in 3 previous trench interventions between 75.25 and 78.00 m OD among the flatter, middle elevations of the site. Redeposited peat was recorded in 4 interventions, with thickness of up to 1.90 m and surface elevation between 73.50 and 79.26 m OD. Nine interventions recorded Victorian to modern made ground deposits, with thickness of up to 1.00 m and surface elevation between 69.16 and 90.07 m OD. Topsoil was recorded in 76 interventions, with a thickness generally of up to c. 0.40 m. In the northeast of the site, thicker topsoil was recorded up to c. 1.00 m. It was considered that the development impacts from the currently proposed substation may affect the in-situ Holocene sequence, which would have a high potential for preserving palaeo-environmental remains dating from the Early Mesolithic / Early Holocene. Proxies provided insight into the changing mosaic of vegetation types, including expansion and reduction of woodland, which may have directly or indirectly affected past human communities. It was recommended that the impact on deposits of interest could be further mitigated through palaeoenvironmental analysis to further constrain the chronology of the accumulation and spread of peat across the site. Palaeo-environmental analysis would provide more detail about the changes in woodland and grass wetland and may provide indirect evidence of the impacts of human activity on the site. <2>