What gives it away is a cropmark, a subtle variation in the colour and growth of vegetation above ground that betrays the outline of a buried fosse, or ditch, beneath. When soil fills a former ditch over centuries, it retains more moisture and nutrients than the surrounding ground, causing crops or grass above it to grow fractionally taller or greener. Seen from the air, this difference can resolve into a clear shape, and in this case the shape is a subrectangular enclosure roughly twenty metres in diameter.

The outline was captured in aerial photography taken in July 1989 as part of a systematic survey of Cork's archaeological landscape. What makes the Cornahinch site particularly interesting is that it does not sit in isolation. Approximately forty metres to the northwest lies a separate circular enclosure, and the whole area falls within a broader field system, suggesting that this corner of North Cork was organised and worked in a way that left layered traces across the terrain. The two enclosures, one circular and one approaching rectangular in plan, were probably not identical in purpose or date, though the evidence available does not allow for confident statements about either. Enclosures of this kind in Ireland are often associated with early medieval settlement, cattle management, or ritual activity, but without excavation the function of the Cornahinch example remains genuinely open.