2006:1418 - CASTLEBAR (and environs sewerage scheme), Mayo

Monitoring of groundworks for pipelaying on the Castlebar and environs sewerage scheme has been ongoing since October 2006. Pipelaying extends all around the town of Castlebar and through its centre, which is itself an RMP site (MA078–003).

Within the centre of the town, several vestigial traces of 18th-century streetscape in the form of small sections of wall foundations, stone-lined drains, paving and well-built stone culverts have been revealed in the pipe trenches. Recently traces have been found of an 18th-century brewery; the pipe trench crossed what may have been the maltings floor and revealed a series of sunken, small wooden vats.

In the more outlying area of this scheme, the pipe trenches crossed some greenfield areas, in the townland of Ballynacarriga, which is on the Pontoon road, about a quarter of a mile north of Castlebar town. A fulacht fiadh was revealed during topsoil-stripping in advance of construction of a pumping station and access road. Digging was diverted away from it and it was fenced off from construction activities. The proposed area for the pumping station did not extend on to the area of this fulacht fiadh; it was not impacted upon by construction of the pumping station.

On the opposite side of this dig, in the south-west corner, topsoil-stripping in advance of construction of an access road revealed a short stretch of timbers laid transversely across the upper surface of the bog. Nine timbers were revealed or partially revealed by the removal of sod and the uppermost layers of peat. It was interpreted as a bog trackway and measured 1.71m in maximum width; a length of 1.54m was revealed during the topsoil-stripping. It appears to run roughly north-west/south-east, possibly originally extending from dryer ground at the base of the hill forming the western and north-western side of this valley, across perhaps as far as the river on the eastern side of this field. This topsoil-strip cleared a fairly large area, but only this portion of the trackway was exposed. It seemed that as the trackway ran towards the south-east it sloped downwards into deeper peat. The revealed portion seemed to be resting higher on shallower peat near solid ground at the western edge of this valley. The access road was diverted away from this feature and it was fenced off from construction. The trackway appeared to consist of two layers of roundwoods; the revealed timbers were resting on a further layer of similar roundwoods. The roundwoods seemed fairly rough; the observable ends were decayed and quite frayed. Two elements (numbers 8 and 9) were dislodged by the digger and several brushwood pieces were scattered around the trackway, also disturbed by the digger. The dislodged elements and the scattered brushwoods were sampled for species identification and specialist analysis. Both of these sites were surface cleaned to reveal more clearly their exposed extents. Both were then photographed, planned, measured and described in detail prior to being reburied as part of the planned reinstating of topsoil in this field.

A second fulacht fiadh was revealed in the pipe trench in the road adjacent to this field. Only a very limited area of the burnt mound was revealed in the narrow pipe (trench width 0.75m, length of burnt stone deposit 3.2m, depth 0.42m), so it was recorded as above and sectioned prior to backfilling of the trench.

In the townland of Knockcroghery, on the shores of Lough Lannagh, the fragmentary remains of a clinker-built boat were discovered during monitoring of topsoil removal on the pipe trench (NGR 113439.669 289608.805). Because of engineering works in the 1840s and 1880s and the Moy drainage scheme in the 1960s, the water level of this lake has been lowered by about twelve feet, therefore the area crossed by this pipe trench, where the boat is lying, was formerly the lake bed. The presence of this boat was first indicated by two planks floating in the machine trench. In looking for a source for these, timbers were noted protruding from the section of the machine-cut trench. The trench was turned away from these timbers to enable further investigation and the feature was revealed as a series of overlapping timbers protruding from the angled section face.

Excavation has revealed this to be the keel portion of a boat lying north-east/south-west, which was built of oak planks held together by iron nails. Only about sixteen planks remain, including the keel; they are very decayed and the sides of the boat have collapsed outwards. It was constructed clinker fashion, where the upper plank slightly overlaps its lower neighbour. The planks are held together by iron nails hammered through the planks and held in place by clench plates on the inner surface of the boat. Portions of two floor timbers, which support the boat internally, also survive. The construction techniques used to build this boat are the same as those used on Viking boats. The boat measures 3.1m by 1.8m.

The boat has been 14C dated to AD 1440–1500 and this is the first evidence that boat-building techniques that had been developed by the Vikings were copied and continued in use up until the late medieval period in the west of Ireland.

Due to the winter rise in the water level of Lough Lannagh, the site has become flooded and excavation has been suspended until late spring.

Roadbridge Compound, Breaffey Road, Castlebar, Co. Mayo