What an aerial photograph captured was a cropmark, the phenomenon where buried ditches and banks cause crops above them to grow at slightly different rates, producing faint colour and height variations that become legible only when seen from altitude. In this case, the cropmark traces two concentric fosses, meaning a pair of roughly circular or oval ditches arranged one inside the other, suggesting a doubly enclosed site of some kind.

The enclosure at Rathbourn belongs to a broad class of curvilinear earthworks found throughout Ireland, which range in date from the Bronze Age through to the early medieval period. Double-fossed examples are of particular interest because the additional outer ditch implies either a heightened concern with defining a boundary, a need for greater defensive depth, or possibly a ceremonial distinction between inner and outer space. Without excavation it is impossible to say whether this was a domestic ringfort, a ritual site, or something else entirely. What the aerial photograph preserves is essentially a ghost of the original structure, the ditches long since silted and ploughed over, leaving only a chemical trace in the soil that plants above them still respond to, season by season.