It exists, for practical purposes, only as a circle of slightly different-coloured grass, visible in a single aerial photograph taken in 1973.

Cropmarks like this one are among the quieter tools of Irish archaeology. When buried ditches or filled pits alter the moisture and nutrients available to the soil above them, the crops or grass growing at the surface respond, appearing darker or lusher along the line of the original feature, even centuries after it was last used. In this way, an enclosure, perhaps a prehistoric or early medieval ringfort-type boundary, can betray its outline from the air on the right day, in the right season, with the right angle of light, and then vanish again entirely. The Townagha enclosure showed itself in that 1973 aerial photograph, a circular form sitting on level ground on a natural ridge amid undulating pastureland. It had not been recorded on the first edition Ordnance Survey six-inch map of 1843, nor on the revised edition from 1952 to 1953, suggesting either that it was already invisible to earlier surveyors working at ground level or that it was simply not recognised for what it was. To complicate things further, a second circular cropmark, slightly smaller, lies immediately to the north-west of this one, the two sites sitting close together on the ridge like a pair of faint signatures left in the land.