2019:764 - 35 – 36 Abbey Street Upper, Dublin, Dublin

The excavations at 35–36 Abbey Street identified the remains of a substantial medieval vertical undershot watermill and timber revetments, most definitely associated with and operated by St Mary’s Abbey as the site lies within the precinct wall (C177) identified at 31–34 Abbey Street to the south-west.

A number of modern buildings, present on the site and along the west side of Abbey Cottage Lane, had been demolished and cleared prior to development in 2018. Beneath these, the remains of basement floors and stone walls of number 35–36 Abbey Street Upper were exposed, though partially cut by modern concrete walls and pits.

Two portions of the same medieval revetment (C32 & C33) were identified to the north-east and south-west and had been cut by a modern pit (C27). Revetment 1 (C32) consisted of two large worked timbers (T1 & 19) set upon a number of supporting timbers (T20–22, 53, 56, 136–142 & 146). A number of timbers stakes (T3, 5–7, 128–130, 134 & 144) were also exposed to the west. A compact layer of organic material and moss (C70) had been placed beneath and around timbers 1, 19 and 20. A similar layer of organic material (C49) had been placed beneath timbers 22 and 53. Two stone deposits (C4 & C5) were identified to the east and west of C32. Revetment 2 (C33) was exposed below a compact dark grey-black clay (C19), to the west of the modern pit (C27) and east of a stone wall (C36), below alternate layers of river deposition and gravels (C29, C30, C31 & C39).

A wattle platform (C60) was exposed in the centre of the site along the eastern edge, south of the modern pit (C27) and north-east of the mill structure (C100). It was represented by a number of fallen wattle screens (C59, C76 & C79), a possible sluice channel (C77) and alternate layers of riverine deposition. It was also beneath the compact dark grey-black clay (C19) and a mid-brown peaty clay and stone layer (C54) and most likely functioned as a wattle platform facilitating access to the mill structure.

The remains of a well-preserved undershot water mill (C100) were exposed below post-medieval soils (C10). It was orientated north-west/south-east and consisted of four main elements — a head race where water entered the mill from a pond or channel; a wheel pit where the water would flow via a sluice gate from the head race into the wheel pit thus turning the mill wheel; a mill structure where the mill stone and various gears and axles would be present and where the grain would be ground into flour, and the tail race, where the now no longer needed water would be channelled away from the mill and back into the river. It is possible that the mill was tidal and used the tidal waters from the adjacent River Liffey, either via a narrow channel or using a series of holding ponds upstream.
A wattle screen (C28), exposed to the south of the mill, was most likely associated with it and may have functioned as a revetment to restrict flooding or silting from the south. A metalled surface (C80) was exposed beneath the revetment (C31 & C32), the stone surface (C4) and grey silty clays containing moderate inclusions of shell fragments and round stone (C11 & C43).

Post-excavation analysis is continuing and it is proposed to update this summary when the analysis is complete.

Unit 21 Boyne Business Park, Greenhills, Drogheda, Co Louth