2001:216 - NENDRUM, Mahee Island, Down

A third season of excavation was carried out between 16 July and 11 December on the substantial remains of this sequence of Early Christian tidal mills. Excavation was confined to the north-east end of the site immediately to the north and north-east of the stone wheelhouse of Phase 3 excavated in 1999 (Excavations 1999, 153). In 2000 Tr. 6 had been opened up to establish whether the sequence of organic deposits and wattle walls continued up to the area of the earliest wheelhouse and to find any possible remains of the wheelhouse and tail-race.

The partial remains of this early wheelhouse were exposed, but while endeavouring to alleviate a problem of constantly running water a platform comprised of large reused timbers and roundwood pieces was exposed at the north end of the trench. It was impossible to deal with this substantial feature in the remaining time so it was decided to cover up the exposed portion of the platform and the partially excavated remains of the Phase 1 wheelhouse and to return for a third season in 2001. An extended area was opened up beyond Tr. 6, 2m to the north and 6m to the east, in order to establish the extent of the timber platform and to investigate the remains of the Phase 1 wheelhouse partially uncovered in 2000 (Excavations 2000, 198). A small trench, 1.5m wide, was opened up across the visible east end of the Phase 3 tail-race to determine the original ground level.

The Phase 1 mill
The poorly preserved remains of the wheelhouse consisted of the basal course of both the back (west) wall, which disappeared below the north side wall of the Phase 3 wheelhouse, and the north side wall. The south side wall had been removed by the construction of the Phase 3 wheelhouse. The rear of the west wall had been packed with a very compact organic layer sealed on the seaward side by red clay. The north wall had been sealed by a bank of red clay, 2m wide by 1.4m high, with an external stone revetment. Only the north side of the Phase 1 tail-race survived. It measured 4.8m long and consisted of a bank of red clay, some 2m wide by 0.8m high, revetted on the inside by a kerb of large stones with a kerb of smaller stones on its outside (north) edge where it overlay the inner edge of the hard standing (see timber platform below). The south side of the tail-race had been removed by the construction of the tail-race for the Phase 3 mill. The wooden flume of this mill was uncovered immediately below the north-west corner of the Phase 3 wheelhouse but very little of it could be exposed and it remains in situ.

The timber platform
Excavation showed that the timber platform located immediately to the north of the Phase 1 wheelhouse and tail-race had maximum dimensions of 8.8m north–south by 3.3m. The platform proved to be a latticework of five layers composed of reused worked timber beams and roundwood pieces up to 0.3m in diameter. The reused timbers, some with mortices and/or tenons, had all been cut to fit into the latticework. At the east end of the platform three of the morticed timbers of the basal layer had uprights driven through the mortice into the underlying sleech to form a secure base to the structure. This feature has been interpreted as a hard standing to allow a boat to moor alongside the mill without sinking into the extremely soft sleech of the seabed around Strangford Lough.

The Phase 3 tail-race
This small trench was intended to uncover the original ground level and to show the method of construction of the two walls of the Phase 3 tail-race. Both these objectives were achieved but excavation also showed that the tail-race continued on out to the east. It could be traced for an overall distance of 8m on the north side and 11.7m on the south. The north wall had been severely damaged, probably as a result of tidal action, and little of it could be exposed without further excavation.

Finds
Including wooden objects, some 132 individual items were recovered. Among the worked wooden objects are stakes and posts removed for tool-mark examination and species identification, large worked timbers (posts and beams), pegs and parts of a wooden container. Small finds include three bone pins, flints (residual), granite fragments, slag, tuyère fragments and five sherds of souterrain ware. Animal bones and teeth, including the greater part of a single skeleton, were also recovered, mainly from silt layers around the periphery of the site.

Environment and Heritage Service, 5–33 Hill Street, Belfast, and Centre for Maritime Archaeology, University of Ulster