Only from the air does the outline become legible: a semi-circular enclosure roughly a hundred metres in diameter, rendered visible not by any surviving wall or earthwork but by the crop growing above it. What lies beneath is old enough to have altered the soil in ways that still influence what grows there today.

The feature was identified as a cropmark, a phenomenon that occurs when buried archaeological features, such as the filled-in ditches of ancient enclosures, affect the moisture retention of the soil above them. In dry conditions, crops growing over a buried ditch tend to stay greener for longer, or grow taller, because the looser infill holds water better than the undisturbed ground around it. Seen from above, these subtle variations in colour and growth trace out the ghost of a structure that may have otherwise left no surface trace. The Ballynavortha enclosure was spotted on Google Earth aerial imagery, with a photograph taken in July 2018 capturing the outline clearly. Enclosures of this kind in Ireland are frequently associated with early medieval settlement, though without excavation it is impossible to say with certainty what purpose this particular one served or when it was built. The semi-circular form is itself slightly unusual; most ringforts and enclosed settlements tend toward a full circle.