No earthwork rises above the grass, no hollow marks the ground. The only record of its existence comes from a single aerial photograph, catalogued as CUCAP ATC 80, in which a cropmark betrays the buried outline with surprising clarity. Cropmarks form when buried features, whether ditches, walls, or pits, affect the moisture and nutrient content of the soil above them, causing the crops or grasses growing there to mature at slightly different rates or to a slightly different colour. From the air, and under the right conditions, these differences can resolve into recognisable shapes that otherwise leave no trace at the surface.

The photograph reveals a circular enclosure, the type of form associated across Ireland with a range of uses spanning many centuries, from early medieval ringforts that once enclosed farmsteads to prehistoric ceremonial sites. At Eminiska, the circle is not complete. Its north-western arc has been cut through by a linear feature running roughly north-east to south-west, suggesting that at some later point a boundary, a field ditch, or a track was driven across the site without any apparent concern for what lay beneath. The relationship between the two features is legible only from altitude; on the ground, the landscape offers nothing.