It escaped the Ordnance Survey's meticulous 1843 six-inch mapping, and it escaped every updated edition that followed. The only reason anyone knows it is there at all is a single aerial photograph taken on 16 April 1974, in which the outline of a roughly circular cropmark betrayed its presence to those who knew what to look for.

Cropmarks form when buried features, walls, ditches, or filled pits, affect the growth of surface vegetation. In dry conditions especially, crops or grasses above a buried ditch tend to grow taller and greener, while those above compacted rubble or stone grow shorter and paler, tracing the invisible geometry below. The photograph in question, catalogued as GSI S.655/654, captured just such a mark, suggesting a circular or near-circular enclosure of the kind that appears across Ireland in considerable numbers, often associated with early medieval settlement, though the date and function of this particular example remain unknown. What survives underground has never been excavated, and nothing is visible at ground level today. A buffer zone has since been established around the monument, prompted in part by recent forestry planting to the east and north, which brings its own pressures to any buried archaeology in the surrounding soil.