What gives it away is the soil itself. In dry summers, when crops draw moisture unevenly from the ground, the vegetation above a buried feature changes colour and height in ways that a camera from the air can read with startling clarity. It is through precisely this phenomenon, known as cropmark archaeology, that an earthwork at Gollierstown came to light.

The site was identified from aerial imagery, including a Digital Globe orthoimage and a separate aerial orthoimage captured in 2018 and held by South Dublin County Council. What the images reveal is a circular area roughly 33 metres in diameter, its outline traced by the cropmark of a buried ditch. A circular enclosure of this kind is broadly consistent with the kind of ringfort or enclosed settlement that was common across Ireland during the early medieval period, though without ground investigation the precise date and function of this particular example cannot be confirmed. The record was compiled by Caimin O'Brien, drawing on details provided by Jean-Charles Caillère, and uploaded to the South Dublin Historical Mapping resource in May 2023.

Because the feature exists entirely as a subsurface trace beneath an active agricultural field, there is nothing visible to a ground-level visitor; the earthwork reveals itself only from above, and even then only under the right seasonal conditions. The 2018 orthoimage accessible through South Dublin County Council's mapping portal gives the clearest picture currently available. For anyone interested in remote-sensing archaeology or in how landscapes hold their secrets, that aerial record is itself the thing worth examining.