The circle, roughly 55 metres in diameter, is the ghost of a fosse, the defensive ditch that once ringed an enclosure, its outline preserved not in stone or earthwork but in the differential growth of crops above buried soil disturbance. It is the kind of discovery that only becomes possible at altitude, in the right season, when parched or waterlogged subsoil betrays what lies beneath.

The enclosure does not stand alone in this landscape. A second enclosure lies approximately 100 metres to the north-north-west, suggesting this part of Rathclogh was a place of some sustained human activity rather than an isolated homestead. More strikingly, excavations carried out 200 to 300 metres to the south-east, undertaken ahead of the construction of the M9 motorway, uncovered a cluster of monuments that fill in something of the local prehistory. Among them was a fulacht fia, a type of ancient cooking site typically identified by a mound of fire-cracked stone beside a trough that would have been filled with water and heated using hot stones, and a corn-drying kiln, which points to later agricultural use of the area. The motorway work, for all its disruption, produced exactly the kind of ground-level investigation that aerial photography alone cannot provide.

The enclosure itself remains unexcavated, known only from that single aerial photograph. Its fosse, if it survives at all beneath the topsoil, has not been ground-truthed in any published record. The cropmark circle is a shape without contents, a boundary whose interior life, and the people who drew that boundary, remain entirely open questions.