No stone protrudes above the surface, no obvious mound breaks the horizon, yet an irregular outline has been recorded from the air, betraying what may be a buried enclosure beneath the soil. It is the kind of feature that most walkers would pass without a second glance, visible not to the eye on the ground but to the camera above.

The site was identified through cropmark evidence, a phenomenon in which buried structures, ditches, or banks influence how vegetation grows above them. Soil disturbed long ago by human activity retains moisture differently from undisturbed ground, and in dry summer conditions that difference shows up as variations in the colour or height of crops and grass. Aerial photographs taken on 24 June 2018 and 12 July 2013 both captured what appears to be an irregular-shaped enclosure at Ballynerrin, the outline emerging as a pattern of differential vegetation growth. Whether the feature beneath is a prehistoric enclosure, a later earthwork, or something else entirely remains unconfirmed. The irregular shape sets it apart from the more geometrically regular ring-forts, or raths, that are common across County Wicklow, though irregularity alone does not rule that category out.