County: Galway Site name: POLLBOY
Sites and Monuments Record No.: SMR 88:10 Licence number: 02E0391
Author: Jerry O’Sullivan, NRA Project Archaeologist
Site type: Canal
Period/Dating: Modern (AD 1750-AD 2000)
ITM: E 585619m, N 729667m
Latitude, Longitude (decimal degrees): 53.317084, -8.215812
Monitoring of an engineering borehole (0.3m in diameter) took place on the towpath (east bank) of the Grand Canal near Ballinasloe. The borehole formed part of the preliminary survey and design work for the N6 Galway–Ballinasloe Road Scheme, which is being developed by M.C. O’Sullivan for Galway County Council and the National Roads Authority.
Construction of the Grand Canal began in 1756, and the main artery, between Dublin and Shannonbridge was completed in 1803. A westward branch linking the Shannon with Ballinasloe in County Galway was completed in 1828 and formally closed in 1961.
Much of this ‘Connaught’ branch of the canal is now abandoned, silted, backfilled or entirely built over by development (in the environs of Ballinasloe, for instance). The current sector is moderately well preserved. The solum is defined by a deep, V-shaped cut between high, broad embankments that carry the towpaths. The embankments support woody scrub and weeds. The solum is deeply silted and supports a variety of weeds, with some dumping of domestic rubbish and construction debris.
All of the Grand Canal is a Recorded Monument, enjoying protection under the National Monuments Acts 1930–94.
The aims of monitoring of the boring operation were to glean information on the materials used in the construction of the canal and to ensure that the monument itself would not be unnecessarily disturbed by the transport and operation of the boring equipment.
The borehole recorded the following sequence of material: compact hardcore to 0.4m; interbanded sand, gravel, silt and peat to 3.9m; silty organic sand to 4.6m; very soft clay/silt to 6.4m; sand and gravel with subangular or rounded cobbles to 9m; and bedrock or large boulders thereafter. The uppermost layers (i.e. to 3.9m) appeared to represent redeposited materials used in the construction of the embanked towpath for the canal. The remaining materials probably represent natural sediments.
If construction work for the proposed road cuts the canal, there will be an opportunity to record its structure and composition in more detail.
Galway County Council
