A cropmark, oval in shape and roughly 45 metres across at its widest point, outlines what appears to be an ancient enclosure, its western side interrupted by a gap that likely marks an original entrance. The feature exists, for now, only as a pattern in grass and soil.

Cropmarks form when buried archaeology influences how plants grow above it. Ditches cut into the subsoil retain moisture and produce lusher, darker growth; compacted banks or stone foundations do the opposite. From ground level nothing may be visible at all, but from the air, particularly in dry summers when contrasts sharpen, these differences become legible. The Ardoyne enclosure was identified in aerial imagery captured on 14 July 2018, a date in midsummer when soil moisture stress would have been at its height and the buried ditch most likely to betray itself. At approximately 45 metres on the longer axis and 38 metres on the shorter, the enclosure falls within a size range common to early medieval ringforts, though without excavation the date and function remain unconfirmed. Ringforts, circular or oval earthwork enclosures, were built in their thousands across Ireland, typically as enclosed farmsteads between roughly the fifth and twelfth centuries. Whether this particular feature belongs to that tradition, or to something earlier or later, is an open question.