That gentle arc, roughly 1.4 to 1.8 metres wide and 1.2 metres high, is almost certainly the last surviving fragment of an enclosure that once measured around 20 metres across. Everything else is gone, levelled into the surrounding ground, leaving only this single southern sweep of stonework still following the original line.

The enclosure itself was probably circular, the kind of modest circular earthwork or field enclosure found scattered across the Irish countryside, often associated with early medieval settlement or agricultural activity. What makes the Cloonyarigaun example quietly interesting is the gap between its documented history and its physical survival. When the Ordnance Survey produced its six-inch maps in 1838, the feature was not recorded at all. By the time the 1930 edition was drawn, it appeared as a semicircular hachured area, curving from northwest to southeast, already partially absorbed into a field boundary along its southern edge. Hachuring on older maps was a cartographic shorthand for earthen banks and raised ground, so its appearance on the later edition suggests the enclosure was still legible in some form by then, even as it was disappearing. At some point after that, the remaining bank was levelled, and the field absorbed whatever was left. Only the southern arc of the field boundary, curving just as the original enclosure once did, preserves the geometry of the earlier structure.