This one exists, as far as anyone can tell from the ground, as almost nothing at all. Near Ballyclogh in north County Cork, a circular enclosure roughly twenty metres across survives only as a cropmark, a faint difference in how vegetation grows over buried soil that becomes legible only from the air. What was once a bank, probably the boundary of a small enclosed settlement or farmstead, has been so thoroughly levelled that a field fence was subsequently laid straight across its interior on an east-to-west axis, indifferent to whatever lay beneath.

The enclosure was identified in an aerial photograph taken in July 1975 as part of the Geological Survey of Ireland Air Photography collection. Cropmarks of this kind form when buried features such as ditches or banks affect the moisture and nutrient content of soil above them, causing the crops or grasses growing overhead to ripen at slightly different rates or reach slightly different heights. When photographed from above in the right season and light, those variations resolve into shapes, outlines, the ghosts of structures that would otherwise be entirely invisible. A circular enclosure of around twenty metres in diameter is a size consistent with a small ringfort, the type of enclosed farmstead that was common across Ireland during the early medieval period, roughly the fifth to twelfth centuries, though without excavation the date and precise function of this particular feature remain unknown.