That ambiguity is, in its own way, the most interesting thing about the place. A cairn, in the Irish prehistoric tradition, is a mound of heaped stones raised over a burial, sometimes containing a passage or chamber, sometimes simply marking the dead beneath. At Knocknacurra, whether any such structures ever existed above ground is a question that has so far resisted a definitive answer.

The trail begins with a pencilled annotation on an Ordnance Survey second edition map, once held in the Department of Archaeology at University College Cork. Whoever held the pencil, a person identified only as John Morrissey, wrote a brief note recording "several large grave cairns" at this location. It is the kind of marginal observation that historians and archaeologists occasionally encounter in old map collections, a fragment of local knowledge committed to paper by someone who presumably saw, or believed they saw, something worth noting. The difficulty is that the map itself has not been located, leaving Morrissey's note unverifiable. When the site at Knocknacurra was subsequently visited and inspected on the ground, no surface evidence of any archaeological monument could be found. The cairns, if they were ever there, have left no visible trace.