It never appeared on any edition of the Ordnance Survey six-inch maps, the standard cartographic record that documented thousands of earthworks, field boundaries, and archaeological features across the country during the nineteenth and twentieth centuries. Its existence came to light not through excavation or fieldwork on the ground, but through a crop mark, the faint differential in vegetation colour and growth that betrays buried features beneath the soil when viewed from above under the right conditions.

Crop marks form when buried ditches or walls affect the moisture and nutrients available to whatever is growing above them. Ditches retain more moisture and produce lusher, taller growth, while buried walls or compacted surfaces starve roots and leave paler, thinner strips. From altitude, these variations resolve into shapes, often the outlines of enclosures, field systems, or settlement remains that have been ploughed flat for centuries. In this case, the mark takes a sub-circular form, the rough ring shape associated with a range of Irish archaeological site types, from prehistoric ring ditches to early medieval ringforts. The precise character and date of this particular enclosure remain unconfirmed, as no excavation appears to have taken place. Its location was recorded through a personal communication from T. Condit, and compiled by Paul Walsh, with the record uploaded to the database in February 2014.

The site sits immediately northwest of an access road to a runway at Casement Aerodrome in Baldonnell, which means public access is not straightforward. The aerodrome is an active military installation, and the surrounding land is not open to casual visitors. For most people, the aerial photograph remains the only practical means of encountering the enclosure at all, and even that requires knowing where to look. Those with a particular interest in aerial archaeology or in the archaeology of the greater Dublin region might find it worth consulting the national record, where the original aerial image and site details are held. The enclosure is a reminder that the landscape holds a great deal that routine survey never captured, and that some sites reveal themselves only when seen from precisely the right angle, at precisely the right moment in the growing season.