2007:1232 - Nymphsfield, Cong, Mayo

Pre-development testing was undertaken in advance of the construction, by Mayo County Council, of a proposed carpark and bus park in Nymphsfield, Cong. The site is located on the east bank of the Cong River and lies within the eastern part of the zone of archaeological constraint around the town of Cong. Cong lies on the shore of Lough Corrib on an isthmus of cavernous limestone, where subterranean rivers flow between Lough Mask and Lough Corrib.
In the late 1840s an attempt was made to construct a canal linking Lough Mask and Lough Corrib. This canal was built to lower winter water levels in Lough Mask and to provide a navigation channel between Castlebar and Galway. Work began in 1848 as a famine relief scheme. However, the works ceased in 1859 before the canal was complete. This was as a result of rising costs, the advancement of rail and in particular the porous nature of the limestone. The canal proved impossible to caulk because the highly fissured karstic limestone would not hold water. Several buildings from the period survive, including the piers and warehouse in Ballinrobe, locks and four miles of the canal. The work in Cong included the cutting of three lock systems into the natural limestone rock. Lock No. 1 was cut near Ashford Castle in the townland of Strandhill, where the water from the Cong River meets Lough Corrib. Lock No. 2 was situated in Cong village. Here a new road into the town was built over a dressed stone canal bridge. This also included a bridge over the Cong River, the water of which was diverted through this new bridge. Lock No. 3 was built further north in the townland of Cregaree.
The proposed carpark is being developed within a plot of land bounded to the east by the Cong River and to the west and south by the Cong to Headford road. This entire plot of land was very densely overgrown, covered with trees and scrub, and strewn with deposits of limestone rubble. A tarred pedestrian pathway built on top of the canal in the 1980s runs north–south through the plot, parallel to the road. This pathway divides the development site into an upper canal area (which corresponds with the proposed bus parking zone) and a lower riverbank area (which corresponds with the proposed car parking zone).
The riverbank area was initially cleared of trees and undergrowth revealing a carved limestone block and several smaller dressed fragments scattered on the surface. These worked stones are redeposited limestone pieces which derived from the construction of the canal. All the dressed stones appear to be discarded architectural pieces. These deposits of stone may have been dumped or may have been carved here for the dressed canal face.
Two trenches were then laid out north–south across the cleared riverbank area of the development site. A cobbled zone was identified at the south-western corner of the plot near the riverbank. The area exposed measured c. 7m by 7.7m. Further cleaning revealed extensive areas of in situ stone foundations of two 19th-century roads which traversed the area.
Further scrub clearance revealed the sides of the canal and several large dressed stones were recovered from stagnant water at the base of the canal.
Chisel marks were identified on individual blocks of limestone and also along the side of the canal. These marks were left after a hole was chiselled into the natural limestone walls of the canal during construction.
A section of the canal in this area was backfilled in the 1980s with construction rubble and rubbish. The upper levels of this material were removed during testing revealing a large natural limestone outcrop together with a section of canal wall.
Mayo County Council, in consultation with the DoEHLG, are currently drawing up plans for the completion of the carpark development, which may require further excavation in this area and/or preservation in situ of the features revealed.