2015:111 - Tawnasool Windfarm, Mayo

An assessment (test trenching) took place of a proposed wind farm located within the townland of Tawnasool, Co. Mayo. The work was carried out on behalf of Kilkenny Archaeology between 23 & 27 April 2015. A total of 33 test trenches were excavated within the site at the locations of 8 proposed wind turbine bases and the site of a proposed substation.
All of the 33 test trenches were located within their original designated positions, however because of the overall site conditions the individual lengths of the trenches had to be changed. Throughout the site the peat deposits ranged between 1.7m and 2.7m. Previous management of the site for peat extraction used a method known as "Sausage cutting" involving the removal of peat beneath the surface, which is then brought up through narrow slits. This method of peat extraction leaves the surface vegetation almost intact. However the removal of the peat leaves linear voids throughout the peat deposits. This makes test trenching of such peat deposits very difficult, leaving the deposits unstable and prone to collapse. Of the 33 trenches 18 trenches collapsed, usually during the excavation of the trenches. As the trenches reached between 5m and 15m in length, the side walls of the trench collapsed, not being able to support the weight of the surrounding bog.
Despite the limitations of the site conditions all trenches were excavated within their original positions. No features or deposits of an archaeological nature were identified nor was there any evidence of deposits of preserved wood in the form of tree stumps, stems or branches; this may suggest limited vegetation development within this area of the bog. This may therefore suggest that at the end of the Ice Age about 10,000 years ago much of the bog may have been originally under water.

Archaeological Consultancy Services Unit, Unit 21 Boyne Business Park, Greenhills, Drogheda, Co Louth