That subsidence, a quiet dip in the earth, is what draws attention here, because it may mark the roof of a souterrain that has given way beneath its own weight over the centuries. A souterrain is an underground passage or chamber, typically stone-lined, built during the early medieval period and associated with the ringforts, or raths, that once served as enclosed farmsteads across Ireland. They were used variously for storage, refuge, or ventilation of food supplies. Most are only discovered when the land above them betrays them, exactly as seems to have happened here.

The ringfort at Ballinard is recorded under its own separate designation, and the suspected souterrain sits within its north-western quadrant. The connection between the two would be entirely typical; souterrains are frequently found inside or immediately adjacent to ringforts, entered from within the enclosed area and running outward beneath the surrounding bank. Whether the passage here is intact below the collapse or has been entirely crushed by the settling ground is unknown. The identification remains tentative, the word "may" doing real work in the original description, which is a reminder of how much of Irish archaeology rests on inference from surface traces rather than excavation.