The larger of the two is a subcircular cairn, a mound of stones heaped up and long since softened beneath turf, measuring roughly 23 metres north to south and 20 metres east to west, rising to about a metre in height. Its outline is irregular, and its north-western edge has been quarried away at some point, suggesting it was once a convenient source of loose stone for whoever needed it nearby. A few metres to the east sits a second, much smaller mound, D-shaped in plan, only three metres across and less than half a metre high. Whether it was raised at the same time, by the same people, for the same purpose as its larger neighbour is genuinely unknown.

Cairns of this kind are among the more enigmatic features of the Irish landscape. The term covers a broad range of stone mounds, from prehistoric burial monuments to simple field clearance heaps, and without excavation it is often impossible to say which you are looking at. The irregular outline and evidence of quarrying at Carnaun complicate any reading further. What can be said is that a natural spring well lies immediately to the west of the larger cairn, and the proximity of a water source to a potentially ancient monument is a pairing that recurs often enough across Ireland to feel deliberate, even if the nature of that relationship here remains unresolved. The field system associated with the site adds another layer of context, hinting at a landscape that has been worked and organised over a long period, with the cairn sitting at its boundary.