Trapezoidal in plan and roughly thirty metres across in each direction, it is defined by a bank about a metre high and an external fosse, or ditch, dropping to around one and a half metres in depth. The fosse is the detail that makes the site quietly interesting: not all enclosures have one, and its presence outside the bank raises the possibility that this was once a moated site.

Moated sites are a particular category of medieval enclosure, typically associated with Anglo-Norman settlement from the thirteenth and fourteenth centuries. They generally consist of a raised platform surrounded by a water-filled or seasonally wet ditch, and were used as defended farmsteads or manorial centres rather than military fortifications. The Ballynora example is cautiously described as a "possible" moated site, which is fair; the earthwork is partially overgrown and its form has been characterised as irregular, which makes confident classification difficult. Walsh, writing in 1985, noted these features and left the question open. What is clear is that the enclosure was already a fixed landscape feature when the first Ordnance Survey six-inch maps were produced in 1842, and it remained visible and mappable on the same series in 1903 and again in 1940, suggesting it has held its shape reasonably well across nearly two centuries of agricultural use.