That greener fringe, running three to five metres wide all the way around, is the visible trace of a fosse, the defensive or boundary ditch that once defined an enclosure, and it is one of the more quietly telling signs in Irish landscape archaeology: where a filled-in ditch retains moisture, the grass above it tends to grow richer and darker than the ground on either side.

The hillock itself measures roughly sixty metres on its north-west to south-east axis and thirty metres across, dimensions that match closely the oval hachured feature recorded on the 1927 edition of the Ordnance Survey six-inch map, where the site appears with trees marked upon it. That map reference is the only formal cartographic record of the enclosure, and the feature had evidently already lost much of its legible form by the time twentieth-century surveyors noted it. The hillock also carries a cairn, a separate though related archaeological feature, and the possibility has been raised that the whole arrangement may once have functioned as a tree-ring, a type of enclosed planting feature sometimes associated with the designed landscapes of larger estates. Cloonyquin House lies approximately six hundred metres to the north-west, which lends that interpretation a degree of plausibility, though the enclosure may equally belong to a much earlier period of land use.