Others exist only as a faint discolouration in a field, detectable not to the eye on the ground but to a camera mounted on a satellite passing overhead. The possible earthwork at Creggane, in County Limerick, belongs firmly to the second category. It has no presence on Ordnance Survey Ireland's historic mapping, no named monument, and no physical feature you could point to from a road. What it does have is a circular cropmark, roughly 55 metres in diameter, picked up in a Google Earth orthoimage captured on 1 April 2021.

Cropmarks form when buried archaeology affects how vegetation grows above it. A filled ditch or a compacted bank beneath the soil can cause the grass or crops overhead to grow slightly differently, retaining or shedding moisture in ways that make the difference visible from altitude, particularly in dry conditions. The Creggane site was identified through the Aerial Survey of Ireland's Aerial Photograph project, compiled by Martin Fitzpatrick and uploaded in August 2021. At the time of recording, the land had been reclaimed as pasture and recently planted with forestry, which makes ground-level investigation difficult. The site sits approximately 240 metres east of a watercourse that marks the townland boundary with Foxhall East. Whether the underlying feature is a ringfort, an enclosure, or something else entirely has not been established; the classification remains a possible earthwork, no more.

For anyone with an interest in landscape archaeology, this kind of site illustrates how much remains unrecorded even in a country as thoroughly surveyed as Ireland. There is no path leading to it and no marker on the ground. The young forestry planting means physical access would be limited and the cropmark itself is no longer likely to be visible in the same way once a tree canopy establishes. The aerial images remain the primary evidence. If you want to see what prompted the record, the Google Earth orthoimage from April 2021 is the place to start, bearing in mind that the faint ring it shows may not reproduce clearly in all viewing conditions or at all zoom levels.