That unevenness, however, has a shape, and the shape is deliberate. Roughly thirty-five to forty metres across depending on the axis you measure, the enclosure is defined not by an obvious bank or ditch but by a very gradual scarp, a low, sloping edge that drops less than a metre at its most pronounced point in the eastern quadrant. This kind of earthwork, levelled over time by ploughing and grazing, is the archaeological equivalent of a watermark: most of the original structure has been worn away, but enough survives to show that something deliberate was once built here.

Circular enclosures of this general type are common across Ireland and typically date from the early medieval period, roughly the fifth to the twelfth centuries, though some have earlier origins. They were used as farmsteads, places of habitation or livestock management, enclosed against the practical pressures of the time. At Ballinderry, the interior slopes gently to the south-east, a detail that suggests the ground was modified or chosen with drainage in mind. In the southern quadrant, the scarp edge becomes poorly defined, as though the boundary was at some point pushed outward or disturbed. A hedgerow now runs north to south across the western quadrant, cutting through the old circular form and making it harder to read as a whole. The northern quadrant scarp has all but disappeared from view. What remains is partial, irregular, and requires some patience to interpret.