A boundary cairn is, at its simplest, a heap of stones placed deliberately to say here and no further, a practical rather than ceremonial monument, though the distinction was rarely so clean in practice. This particular example sits on the high ground between Carrignabinnia and Slievecushnabinnia, on the boundary separating the townlands of Lyre and Carrigeen Mountain, and it forms part of a loose chain: two companion cairns lie 40 metres to the west and 120 metres to the east, suggesting that whoever set out this boundary did so with some care and regularity.

What makes the site quietly interesting is the way the cartographic record tracks its gradual disappearance. The Ordnance Survey's six-inch map of 1840 does not mark it at all, which hints either that it was not considered significant enough at the time of the first survey, or that its form was already ambiguous. By 1897, the 25-inch edition annotated it simply as 'Mound', a label that reflects genuine uncertainty rather than knowledge. The Cassini edition of the OSi six-inch map depicted it as a small, circular-shaped mound, but by the time Digital Globe ortho-imagery was captured between 2011 and 2013, no surface remains were visible, a finding confirmed by Google Earth imagery. The cairn, or what was left of it, had effectively been absorbed into the rough pasture of the ridge.

Access to the ridge between Carrignabinnia and Slievecushnabinnia involves crossing open upland terrain, and the site sits in rough grazing land without any formal path or signage. Anyone walking the area with an interest in historic landscape boundaries would do well to consult the OSi maps alongside the Archaeological Survey database entry, compiled by Fiona Rooney and uploaded in November 2021. On the ground, there is little or nothing to see at the recorded location; the value here is less in the physical remains than in what the map sequence reveals about how a feature can move from unnamed ground, to mound, to nothing visible at all across fewer than two centuries of observation.