This is a ring-ditch, a type of circular earthwork that typically survives as the filled-in remains of a prehistoric burial monument, and here it leaves no surface trace whatsoever. The only reason anyone knows it exists is because an aerial photograph, taken on 11 August 1996, caught the faint discolouration in the crop that marks it from above.

Cropmarks of this kind appear when buried features such as ditches or pits cause the soil above them to retain moisture differently from the surrounding ground, producing subtle variations in plant colour and height that are invisible at eye level but legible from the air. The Ballyda ring-ditch came to light through exactly this process. What makes it more intriguing is that it does not appear to be alone. Two further ring-ditches were identified in the same area, one lying approximately 63 metres to the north-east, another around 300 metres further in the same direction. The clustering of three such features within a relatively compact area raises the possibility that they form part of a barrow group, a prehistoric funerary landscape in which burial monuments were placed in deliberate proximity to one another, a practice well documented in Irish and British archaeology from the Neolithic through to the Bronze Age.