It leaves no visible trace above ground, no raised bank, no hollow, no obvious break in the soil. Its existence became apparent only when a satellite passed overhead on a dry July day in 2018 and the cropmark betrayed it.

Cropmarks form when buried features alter the rate at which crops grow above them. A filled-in ditch retains more moisture, so crops above it grow taller or stay greener longer; a buried wall or compacted surface does the opposite. From ground level, these differences are invisible. From the air, in the right season and the right conditions, they resolve into shapes. The enclosure at Dungarvan Glebe is roughly circular, with a diameter of approximately 35 metres, and was identified in Google Earth Pro imagery dated 14 July 2018 by Jean-Charles Caillère, Simon Dowling, and Edward O'Riordan. A road running roughly east-west has clipped its south-western edge, removing whatever lay there before the route was established. A second enclosure, identified by the same method, sits roughly 95 metres to the north-west, raising the possibility that whatever activity generated one site was connected to the other, though what that activity was remains open.

Circular enclosures of this scale in an Irish context are often associated with early medieval settlement, the enclosed farmsteads commonly called raths or ring-forts, though without excavation it is impossible to assign a date or function with any confidence. The site lies in tillage, which is precisely the condition that makes cropmarks readable, and it is the seasonal rhythm of that same agriculture that keeps the enclosure visible only briefly each year, in dry summer weather when crops are under stress and the buried past has the best chance of showing through.