A field in Kinnafad, County Kildare, holds the ghost of a structure that has not been visible at ground level for centuries. What betrays it is the crop growing above it: a subtle variation in colour and height that appears only under the right conditions, when parched soil over buried ditches and banks causes the vegetation above to ripen or wither at a different rate to the surrounding land. These cropmarks, as they are known, can render entire enclosures, field systems, and settlement traces legible from the air in a way that no amount of walking the ground would reveal.

The enclosure at Kinnafad came to light on 21 July 1989, when Dr. Gillian Barrett photographed it during an aerial survey. The resulting image, recorded as photograph GB89.AM.27, shows the cropmark of a curvilinear, D-shaped enclosure defined by a fosse, which is an external ditch typically dug as part of a boundary or defensive circuit, with an entrance oriented to the east. D-shaped and roughly circular enclosures of this kind are a familiar but poorly understood feature of the Irish landscape; they are associated with a broad range of periods and functions, from early medieval farmsteads to earlier prehistoric activity, and without excavation it is rarely possible to say which applies. The fosse visible in the cropmark suggests the enclosure was once a physically substantial feature, even if nothing of it now protrudes above the ploughsoil.