A circular enclosure roughly 66 metres across, visible as a cropmark, emerges from the earth only when conditions are right, its presence betrayed by the differential growth of whatever crop happens to be planted above it.

Cropmarks appear when buried features such as ditches, walls, or pits affect the moisture and nutrient content of the soil above them. A filled-in ditch retains more water than the surrounding ground, encouraging denser, faster growth, while a buried wall does the opposite. From ground level these variations are invisible, but from the air, especially in dry summers when crops are under stress, the underlying archaeology becomes legible as patterns of darker or lighter vegetation. In this case, the ditch of the enclosure is traceable from the south-east around to the north, describing much of a circle approximately 66 metres in diameter. Circular enclosures of this kind are a common feature of the Irish landscape, ranging from prehistoric ring-ditches to early medieval raths, the latter being enclosed farmsteads typically surrounded by an earthen bank and ditch. Without excavation it is impossible to assign a period or function to the Ballynafeaha example with any confidence. What is known is that it was first identified not by an archaeologist in the field, but by Jean-Charles Caillére examining Bing satellite imagery, a reminder that aerial and remote-sensing platforms have quietly transformed the pace at which buried sites come to light across Ireland.