The feature only came to light through aerial photography, and even then it revealed itself not as a structure but as a shadow in the crops.

What the aerial photographs captured, taken in July 2000, was a cropmark: a subtle difference in the colour and growth of vegetation above ground that betrays buried archaeology beneath it. In dry summers, crops growing over a filled-in ditch, known in archaeological terms as a fosse, tend to stay greener and grow taller than those rooted in undisturbed subsoil, because the looser, moister fill retains more water. The result, invisible from the ground but legible from the air, is a ghost of the original feature. In this case the cropmark traces a circle roughly thirty to forty metres in diameter, the outline of a fosse that once defined the boundary of an enclosure. Circular enclosures of this kind are among the most common monument types in the Irish landscape; many are the remains of ringforts, farmsteads of the early medieval period typically surrounded by an earthen bank and outer ditch, though without excavation it is not possible to say with certainty what this one was or when it was built.

The enclosure had gone unnoticed for so long partly because nothing survives above the surface to catch the eye, and partly because the fosse has been filled in gradually over centuries of ploughing, leaving the field apparently flat and unremarkable. Its identification depends entirely on the angle of light, the right crop at the right stage of growth, and a dry enough summer to stress the vegetation unevenly.