What the camera caught was a cropmark, the faint but legible trace left in growing vegetation when buried ditches or banks alter the moisture and nutrient content of the soil above them. In this case, the mark describes a curving arc running from west to north-east, suggesting two closely spaced concentric fosses, or ditches, enclosing a roughly circular space with an inner diameter of around 25 metres.

Cropmarks like this are among the quieter forms of archaeological evidence. They require the right crop, the right angle of light, and often a period of dry weather to become visible from the air, which means the same field photographed a week earlier or later might reveal nothing at all. The arc here sits on the north side of a field fence, and it does not form a complete circle, so the full extent of the original enclosure remains uncertain. What makes the location more intriguing is that a possible ringfort, a separate site, lies roughly 120 metres to the north-north-east within the same field. Ringforts, the most common monument type in the Irish landscape, were typically circular enclosures defined by an earthen bank and ditch, used as farmsteads during the early medieval period, broadly the fifth to twelfth centuries. Whether the two features at Curragh are contemporary with one another, or belong to entirely different periods of activity, is unknown.