Only from above, under the right conditions, does it reveal itself: a cropmark, the faint discolouration in growing vegetation that betrays buried archaeology beneath the surface. Cropmarks form because filled-in ditches and disturbed soil retain moisture differently from undisturbed ground around them, causing crops above them to grow at subtly different rates, and so produce visible patterns when viewed from altitude. At Tomgarrow, the pattern that emerges is a near-square enclosure, its interior measuring roughly 27 metres by 24 metres, with an overall footprint of approximately 36 by 35 metres.

What makes the site particularly interesting is its construction: rather than a single boundary ditch, the enclosure appears to have been defined by two parallel fosses, or ditches, set approximately four metres apart. This double-fosse arrangement suggests a degree of deliberate effort and possibly defensive intent, though the site has not been excavated and its date and function remain unknown. The outer ditch on the north-east side runs close to an existing field bank, and the north-east quadrant of the interior has been disturbed by a later U-shaped trench, which descends from the field bank and returns to it, cutting into whatever lies beneath. The site was first identified by Simon Dowling, who noticed it on a Google Earth image captured in July 2018, a reminder that aerial and satellite imagery continues to add to the archaeological map of Ireland, sometimes in the most unassuming corners of the landscape.