From the air, however, the outline becomes readable: a subrectangular area roughly fifteen metres east to west and nine metres north to south, its edges betrayed by an overgrown field bank, a low scarp no more than 0.4 metres high, and a band of wetland rushes tracing the perimeter. That combination, an anomalous shape that reads clearly on aerial photographs but fades almost to nothing at eye level, is precisely what makes this kind of site so easy to walk past without registering.

The feature at Cornulla is classified as an enclosure, a broad archaeological term covering anything from an early medieval settlement boundary to a prehistoric farmstead defined by a bank and ditch. Whatever its original purpose, later agricultural activity has complicated the picture considerably. A north-to-south field wall cuts across the western side of the enclosure, overlaying it entirely in places, and the field bank along the northern edge may itself have removed a significant portion of the original structure. The working interpretation is that what survives is only the southern section of something once larger, the rest having been erased or obscured by centuries of land management. Michael J. Moore, compiling the Archaeological Inventory of County Leitrim published in 2003, recorded it in this fragmentary state, noting its visibility as an anomalous feature on aerial survey.