A cropmark, roughly fifteen metres across, betrays the outline of an ancient earthwork, the kind of feature that only becomes apparent when drought or differential soil moisture causes the vegetation growing over buried features to ripen or wither at a different rate from the surrounding field. It is, in other words, a ghost that satellites can see and feet cannot.

Cropmarks like this one are among the quieter tools of landscape archaeology. Where an earthwork has been levelled by centuries of agriculture, the filled ditches and compacted banks beneath the surface retain moisture differently from undisturbed ground, and that difference shows up in aerial imagery, particularly during dry summers. The Forgney example is square in plan, which is a shape associated with a range of features in the Irish archaeological record, from enclosed farmsteads to ritual or funerary enclosures. What makes its situation at Forgney particularly interesting is that it does not stand alone. A second square cropmark of comparable form lies approximately forty metres to the east, suggesting a pairing or sequence of enclosures that may once have related to one another in function or in time. Whether they are contemporary, or separated by generations, is not something the surface evidence alone can answer.