Somewhere between Lismore and the sea at Ardmore, a stretch of public road passing through the townlands of Monea and Duffcarrick carries an old Irish name that hints at something stranger beneath it: Bóthar na Trínse, the trench road. The name suggests a sunken or embanked way, the kind of feature that often marks out a route of some antiquity, and in this case the road forms one legible section of what was once identified as a continuous ancient highway crossing the Decies, the historic territory that corresponds roughly to County Waterford.

The route was traced in detail by the Reverend Patrick Power, writing in the Journal of the Royal Society of Antiquaries of Ireland in 1905. Power argued that this road, known in tradition as the Rian Bó Phádraig, the track of Patrick's cow, connected Lismore and Ardmore along a course that followed country lanes and farm tracks for most of its length. The Rian Bó Phádraig belongs to a class of early medieval routeways associated in legend with St Patrick, and Ardmore, with its ancient cathedral church, was a significant ecclesiastical destination in Munster. Power could trace the route across much of the landscape, but found a gap of roughly 1.7 kilometres northeast of Grange church where it vanished entirely. It picks up again in Ballynamertinagh as a farm track running for about 900 metres, then continues as a public road for approximately 1.6 kilometres between Monea and Duffcarrick before arriving at Ardmore. The survival of the name Bóthar na Trínse along that latter section is the kind of linguistic fossil that tends to outlast the physical evidence by centuries, preserving in everyday placename usage what the landscape itself has long since obscured.