It was picked out from the air on an aerial photograph taken in July 1968, appearing as a cropmark of a fosse, the term for the ditch that would originally have surrounded a rath or ring-fort. A fosse shows up in growing crops because disturbed or silted soil retains moisture differently from undisturbed ground, causing the vegetation above a buried ditch to grow taller or ripen more slowly, tracing the old outline in subtle colour from altitude. There is even a suggestion of a second, outer concentric fosse, hinting that what survives as a faint stain in the earth was once a more substantial enclosure.

By the time the first edition Ordnance Survey six-inch map was made in 1839, and again when it was revised in 1900, the site had disappeared entirely from the surveyors' view, presumably levelled by centuries of agricultural activity. A local antiquary named Prim, writing in 1872 to 1873, published a map charting the distribution of raths across Dunbel townland and noted one site, labelled simply as 'A', on Prospect farm, which he described as 'nearly obliterated'. Whether Prim's 'A' and the cropmark enclosure are the same feature is uncertain. His map is considered reasonably accurate, and if the locations are taken at face value, the site he labelled would fall about 180 metres to the south-west. Two further enclosures identified as cropmarks, lying around 150 metres to the south, complicate the picture further, as either of those could equally be what Prim was describing. The result is a small cluster of vanished or near-vanished earthworks in close proximity, each a candidate for the same brief, uncertain mention in a nineteenth-century antiquarian record.