2012:564 - NENAGH CASTLE, Tipperary

The excavation of service trenches and associated manholes was monitored in March/April 2012. Some of the service runs and associated manholes extended through an area that has already been partially excavated. A limited excavation was also carried out inside the keep in April 2012.

The trenching would be limited to areas of previous disturbance. It was also indicated that the edge of the moat associated with Nenagh Castle, and known to survive along the route of the proposed ducting, was discovered by Miriam Carroll, Tobar Archaeology, at a depth of 56m OD in Cutting 1, and at 56.3m OD in Cutting 4 (Excavations 2007, No. 1706). The proposed ducting layout indicated existing ground levels in the area of the moat at 57.21m OD, 57.13m OD etc. This suggested that all necessary trench and manhole excavation in this area should potentially manage to avoid the edge of the moat and associated material/features which are known to survive 0.8m below present ground level in some areas.

Additional monitoring was carried out in March and April 2012. This involved monitoring of a trench for a ground termination system for a lightning conductor. This was excavated in a circular direction around the keep at a distance of 2m, but 3m from the wall where the scaffolding is in place. Gravel and topsoil were noted in the trench fill. The trench averaged 0.3m deep, and was approximately 28m in length, north-north-west/south-south-east. No archaeological features were noted. This trench was extended in a south-south-west direction for approximately 30m. It averaged 0.4m deep and 0.5m wide. Its depth meant that the bottom of the trench was above the known archaeology levels. No archaeological features were noted. The spoil was also metal detected. No archaeological artefacts were recovered.

A short trench, 0.6m deep was excavated through previously disturbed ground, leading from a previously monitored ducting pipe, in a westerly direction into a percolation area. No archaeological features were noted.

Two stretches of pipe trench for a CCTV cable were also monitored. The shortest was to the south-east of the keep, and extended from an existing manhole for a distance of approximately 15m in a northerly direction. The trench was 0.5m wide, 0.7m deep. It terminated in 1m by 1m wide excavated hole, 0.7m deep for a CCTV pole. Yellow boulder clay was encountered at the bottom of this hole. No archaeological features were noted. A second trench was excavated for a CCTV cable and pole at the north side of the keep. This ran from an existing manhole at the entrance to the keep, in a north-north-east direction for 28m. This trench was 0.7m deep at south, 0.5m deep at north. It was cut through topsoil, with yellow boulder clay encountered at a depth of 0.5m. No archaeological features were noted.

Six fence posts were excavated at the west side of the keep. These varied between 0.6-0.7m in depth, and were cut through gravel, with rubble and brick also noted. Two gateposts were also monitored. These were 0.7m by 0.7m, and 0.8m deep. These were cut through topsoil and rubble (containing brick). Boulder clay was encountered at a depth of 0.6m. No archaeological features were noted.

In addition to the monitoring, limited excavation was conducted within the keep (see Excavations 2012, No. 565). A circular stone-filled cut was identified by Dave Pollack measuring 3.5m in diameter. The largest stones had been placed with their long axes aligned radially against the outside of the cut. The excavation revealed alternating deposits of rubble and compacted clay. It appears that, after a layer of stones had been placed within the cut, clay was deposited and compacted down till it formed a relatively level finish. This sequence continued to the surface with the thickness and compaction of the layers increasing with depth. The base of the feature was not achieved with the excavation having to be stopped at a depth of approximately 1.2m. At this level the stones had become significantly bigger than those at the top.

No clear evidence of the feature’s function was revealed. The alternating bands would suggest that these layers were deliberately laid down. It is possible however that this is the remains of a foundation for a central pillar, which was abandoned at an early stage and was never constructed (Con Manning, pers. comm.) No artefacts were recovered.