What gives it away is not stonework or earthwork but a subtle difference in the colour of crops growing above it, a phenomenon known as a cropmark. When soil is disturbed by ancient digging, the ground retains moisture differently, and during dry summers the plants rooted above buried ditches tend to grow taller and greener than those around them. Seen from the air, those variations resolve into shapes, and the shape at Ballybrack is a double ring.

The enclosure was identified in aerial photographs taken in July 1989 as part of a systematic survey of County Cork. What the photographs showed were two concentric fosses, that is, ditches cut into the earth, arranged in an oval with a long axis of approximately thirty metres running east to west. Double-ditched enclosures of this kind are associated with early medieval settlement in Ireland, though without excavation it is not possible to say with certainty what this particular site was used for or when it was occupied. The overall scale suggests a domestic farmstead rather than anything ceremonial or defensive, though the two concentric ditches hint at something a little more considered than a simple agricultural boundary.