No earthwork rises from the ground, no stones break the surface, no obvious feature interrupts the ploughed field on its east-south-east-facing slope in north County Cork. And yet, in 1984, an aerial photograph revealed the ghost of something that had been there for a very long time: a cropmark tracing the fosse, or defensive ditch, of an oval enclosure roughly forty-five metres in diameter, pressed into the soil and readable only from the air, only under the right conditions of crop stress and sunlight.

Cropmarks form when buried features, such as the filled-in ditches of ancient enclosures, affect how crops grow above them. Soil that was once disturbed tends to retain moisture differently from undisturbed ground, and in dry conditions this produces faint variations in colour and height that are invisible at ground level but legible from above. What the 1984 photograph from the Cork Aerial Survey and Aerial Photography project captured was the outline of a fosse belonging to an oval enclosure, and alongside it, overlapping on its western side, the ditch of a second, larger enclosure. The two structures are clearly distinct, their boundaries cutting across each other in a way that suggests they were not built at the same time, one preceding the other, though the sequence is not recorded. Both sit within a wider field system, indicating that this was not an isolated feature but part of a longer-used, more densely occupied landscape.