The outcrop itself is modest, rising no more than 0.75 metres above the ground on a north-west-facing slope at around 169 metres above sea level, overlooking the Behy River valley to the north and backed by mountains to the south-east. It would be easy to walk past without registering it at all.

The decoration belongs to the tradition of prehistoric rock art found across Atlantic Europe, in which cup-and-ring motifs, concentric carved circles surrounding a central depression, were pecked into exposed stone surfaces, most likely during the Neolithic or Bronze Age. At Ballynakilly, the carving is concentrated towards the southern end of the decorated face. A natural fissure running north to south splits the surface, with grass growing along it, and this divide has effectively separated the motifs into two groups. To the east of the fissure sits one partial cup-and-ring: a cupmark roughly six centimetres across with a half-ring open to the south. To the west, a second cup-and-ring of similar scale has its half-ring open to the north. Five further plain cupmarks, shallow circular depressions with no surrounding rings, are distributed across both sides of the fissure, four to the west and one to the east. A second rock art site lies approximately fourteen metres to the north-west, suggesting this small slope held some repeated or sustained significance for the people who worked these surfaces.

The motifs are described as very weathered and faint, which is worth bearing in mind. Oblique light, particularly in the lower sun angles of morning or late afternoon, tends to pick out shallow carvings like these far more clearly than direct overhead light, which flattens the surface and renders the marks nearly invisible.