This one near Rockspring in north County Cork exists only as a shadow in a summer field, legible from the air but invisible underfoot. What survives is a cropmark, the kind of ghostly trace that appears when buried earthworks cause the soil above them to retain moisture differently, producing variations in vegetation growth that only reveal themselves to a camera pointing downward from a low-flying aircraft.

The cropmark was captured in a single aerial photograph taken in July 1969, part of the Cambridge University Collection of Aerial Photography, reference AYQ16. What it shows is the outline of a bank and fosse running roughly north to south along the east side of a field fence, with a fainter return of the fosse visible on the west side. A fosse, in this context, is simply a ditch dug to accompany an earthen bank, the two together forming the characteristic enclosure of an Irish ringfort. The estimated diameter of around thirty metres places this at the smaller end of the ringfort spectrum. Ringforts, known in Irish as raths, were the most common form of rural settlement in early medieval Ireland, typically consisting of a circular bank and ditch enclosing a farmstead. Most date from roughly the sixth to the tenth century, though many were built and used outside those limits. The Rockspring example has not been confirmed by excavation, and the qualifier "probably" does real work here; the cropmark evidence is suggestive but not conclusive.