No mound, no ditch, no ring of stones. What gives this site away is the grass itself, or more precisely, the way crops and vegetation grow differently over buried features, producing subtle variations in colour and height that only become legible from the air. At Ballynoe, on the demesne lands of Ballynoe House in County Limerick, aerial imagery has revealed just such a cropmark, tracing the outline of a roughly circular earthwork approximately 65 metres in diameter.

Cropmarks of this kind form when buried ditches or banks alter the moisture and nutrient content of the soil above them. Ditches retain more water, producing lusher, darker growth; compacted banks have the opposite effect. The result, under the right lighting and at certain times of year, is a ghost of whatever once stood at ground level. The Ballynoe enclosure was identified from Digital Globe aerial imagery, including Google Earth photographs taken on 16 March 2016, and was compiled by Caimin O'Brien on the basis of details provided by Jean-Charles Caillère, with the record uploaded in April 2020. The circular form, roughly 65 metres across, is consistent with a range of enclosure types found across Ireland, from prehistoric ceremonial monuments to early medieval ringforts, which were typically circular earthen enclosures used as farmsteads or defended residences. Without excavation, assigning a date or function to this particular feature would be speculation.

Because the enclosure is essentially invisible at ground level, visiting with any expectation of seeing the monument directly is likely to disappoint. The site sits within the demesne of Ballynoe House, so access would require appropriate permissions. The aerial photographs that revealed the feature were taken in mid-March, when low sun angles and seasonal vegetation patterns make such cropmarks more legible. Anyone with an interest in remote-sensing archaeology can examine the site using freely available satellite platforms, where the circular outline, once you know to look for it, is faintly but clearly present in the right imagery.