A roughly circular cropmark, around 25 metres in diameter, emerges in aerial photography as a ghostly ring pressed into the grass, the kind of feature that passes entirely unnoticed at ground level but speaks clearly to anyone looking down from above.

Cropmarks of this kind form when buried features, such as ditches, walls, or pits, alter the way moisture moves through the soil above them. Crops or grasses growing over a buried ditch, which tends to retain more water, often grow taller and stay greener longer, while those over a compacted bank or buried wall may thin and yellow more quickly. The result, visible in dry summers or under particular light conditions, is a pattern that maps what lies beneath without any excavation at all. The Corgrig example, a circular form at roughly 25 metres across, is consistent in scale and shape with an early medieval enclosed settlement, the kind of site commonly known as a ringfort, though without investigation the precise date and function remain open questions. The site was documented by Matt Kelleher, drawing on information supplied by Gerard Curtin, and recorded as recently as July 2023.

The enclosure is located in working farmland, so access would require the permission of the landowner. There is nothing to see from the road or on foot in the field itself; the feature exists, in a practical sense, only in the photographic record. Those with an interest in aerial archaeology or in the wider landscape of early settlement in County Limerick can find the site catalogued through the relevant heritage databases, where the aerial imagery gives the clearest impression of what the ground is quietly holding.