Walk across the field and you would notice nothing unusual underfoot; the feature has no visible earthworks, no upstanding banks, no obvious trace of what was once there. Yet from satellite imagery captured in March 2010, a cropmark appears clearly, a roughly circular mark approximately 45 metres across its northeast to southwest axis, the underground remains of the old boundary drawing a ghostly outline in the growth of the grass above.

A cropmark of this kind forms when buried ditches or banks alter how soil retains moisture, causing the vegetation above to grow at a slightly different rate or to a slightly different colour from the surrounding land, differences that are invisible at eye level but become legible from above. The enclosure at Ballydowel Big has a long, if sparsely documented, history of recognition. It appears as a 'Rath' on the Grand Jury barony map of Crannagh, produced between 1812 and 1824; a rath being the Irish term for a roughly circular earthen enclosure, typically of early medieval date, used as a farmstead or settlement. By the time the Ordnance Survey produced its first edition six-inch map in 1839, the site had already been omitted, and it was absent again from the 1900 revision, suggesting that by the nineteenth century the surface evidence had largely disappeared into the improved agricultural land around it. The southeastern quadrant of the enclosure appears to be absorbed into woodland growing at the edge of the gorge to the south, which may account for some of the erosion or obscuring of that portion of the monument.