2011:459 - ROUNDHOUSE 2, SLIEVEMORE, Mayo

During 2009 (Excavations 2009, no. 625) and 2010 (Excavations 2010, no. 506) the Achill Field School undertook extensive excavations of a large, stone-built Middle Bronze Age roundhouse, known as Slievemore Roundhouse 2. By the end of 2010 it was apparent that four pre-bog walls connected to the perimeter of the building, at the north-east, south-east, south-west and north-west. These walls are part of a vast pre-bog wall system that can be seen protruding through the surface of the bog on the south-western slopes of Slievemore mountain. In 2011 the licence was extended to cover the excavation of a series of small trenches designed to examine two of the walls attached to Roundhouse 2. Three of the trenches were excavated in order to examine the wall extending from the south-east of the building, and a single trench was placed over the wall extending from the south-west of the building.
Trench 8, 5m south-east of Roundhouse 2, measured 6m by 1m and ran from north-east to south-west. A large, stone-built wall ran through the centre of the trench, from north-west to south-east; it consisted of an intact core, with damaged and collapsed areas to the north-east and south-west. The core of the wall consisted of a mixture of variously sized stones arranged in rough courses. It was 1.32m wide and up to 0.62m tall. To the north-east of this there was a spread of disorganised stones up to 1m in width. These probably represent the basal layers of the wall which had become badly disturbed either through deliberate removal of stones or gradual collapse. To the south-west of the intact core there was a spread of stone up to 1.4m wide that was confidently identified as collapse from the wall. The total width of the wall in this trench would therefore have been around 2.3m. The wall and the collapsed material rested on the mineral soil and were covered by deep peat deposits interspersed with deposits of coarse sand.
Trench 9, located 33m south-east of Roundhouse 2, measured 6m by 1m and ran from north-east to south-west. Removal of the overlying peat deposits exposed a natural spread of stone interspersed with patches of mineral soil. The stones were highly concentrated in the central and southern parts of the trench, while the northern part contained a less dense spread. Initially the southern concentration of stone was thought to have been the base of a collapsed wall, but by the end of excavation it was concluded to have been a natural rock formation. Shallow peat deposits were recorded above this layer of stone and mineral soil.
Trench 10 was rectangular and was located 23m south-east of Roundhouse 2. It measured 6m by 2m and ran from north-east to south-west. It contained a substantial stone-built wall running diagonally through the trench from the north-west to the south-east. The most substantial component of the field wall was a row of large stones which defined the northern-eastern face of the wall. This part of the wall had a maximum width of 1.1m and a maximum height of 0.5m. To the south of this was the second major component of the wall, which consisted of a mass of medium-sized rounded stones with larger stones occasionally present. They formed a band with a maximum width of 1.8m and a maximum height of 0.3m. To the north-east of the wall there was a spread of collapsed material up to 1.5m in width, and to the south-west there was a further band of collapsed material that was at least 1.5m wide but extended beyond the southern limit of the trench. The total width of the wall in this trench would therefore have been around 2.9m. The wall and the collapsed material rested on the mineral soil and were covered by deep peat deposits interspersed with deposits of coarse sand.
Trench 11 was located several metres south-west of Roundhouse 2. It measured 6m by 2m and ran from north-west to south east. A stone-built field wall ran across the north-western end of the trench. It consisted of a band of medium and large stones interspersed with firm soil, and measured 0.7m in width and 0.44m in height. There were no defined wall faces and, given the low height of the wall and the presence of soil amongst the stones, it seems that the wall had either totally collapsed or had been extensively robbed out. At the south-eastern end of the trench a curving line of stone was encountered. It consisted of just one course of large and small rocks and extended out from the middle of the south-eastern section of the trench into the edge of the south-western section. The exposed curve was 1.23m long and up to 0.39m high. It was set on a soft sandy deposit that overlay the mineral soil. If the curving wall formed a complete circle, its estimated diameter would not have been greater than 1m. Further excavation would be required to establish the nature of this feature. The wall at the west of the trench rested on the mineral soil and was overlain by deep peat deposits interspersed with deposits of coarse sand, which also covered the small curving wall.
Although no dating information was obtained during these excavations, it was clear from the previous year’s excavations that both of the walls investigated met the wall of the roundhouse in clean joins and that there was no collapsed material between the end of the walls and the edge of the building. This suggests that they are contemporary with or only slightly younger than the roundhouse, which has been radiocarbon-dated to 1431–1314 BC.

Achill Field School