There is no mound, no visible earthwork, no obvious sign that anything lies beneath. The land rises only slightly to the north-north-east, and the ground is dotted with small hummocky tufts and subtle undulations, the kind of minor irregularities that could belong to any well-grazed Irish pasture. The ring-ditch only reveals itself from the air.

A ring-ditch is the residual trace of a circular ditch, most commonly the boundary feature of a prehistoric burial monument. Over centuries, the upstanding elements erode away and ploughing reduces what remains to near nothing, but the ditch itself, once backfilled with looser soil, retains moisture differently from the surrounding ground. In summer, when crops or grass grow above it, this differential shows up as a crop mark or soil mark, a ghostly outline that becomes legible only at altitude. The Clonmore example was identified in precisely this way, spotted on an aerial photograph taken in August 1996, when the field was under tillage and the conditions were right to betray what the ground conceals. Without that photograph, there would be no record that anything out of the ordinary lay there at all.