The site, in Derk townland, never appeared on historic Ordnance Survey Ireland maps, which is itself a small puzzle. Its existence only became apparent when aerial photography began to register what ground-level observation had missed entirely.

The pattern was first identified during a Bruff aerial photographic survey in 1986, recorded as image AP 4/3626, which showed a series of rectilinear enclosures laid out across the landscape. Cropmarks, for the uninitiated, form when buried features such as ditches or walls affect how plants grow above them, creating variations in crop colour or height that become visible from altitude, particularly in dry summers when stress in the vegetation is most pronounced. The Derk marks, some running perpendicular to one another, cover an area roughly 400 metres northwest to southeast and 250 metres northeast to southwest, spread across four fields. They sit within the demesne lands of Derk House, located approximately 600 metres to the north, and are surrounded by a notable concentration of barrows, the low earthen burial mounds of prehistoric communities, clustered across the southern half of the townland. The cropmarks remained visible on an Ordnance Survey orthophoto taken between 2005 and 2012, and again on a Google Earth image dated 20 September 2020. Despite the initial interpretation as a field system, closer analysis by Martin Fitzpatrick, who compiled the site record in April 2021, suggests the linear marks are more likely the remains of drainage ditches than evidence of a pre-1700 field system.

There is nothing to see at ground level, which is rather the point. The site sits on private demesne farmland, and the rectilinear pattern is only legible through aerial or satellite imagery. Those interested in exploring the wider landscape of Derk townland would do well to consult the available orthophotos and the Bruff aerial survey archive. The proximity of multiple barrows makes the broader area archaeologically dense, and comparing the cropmark evidence against historical mapping, where this site conspicuously does not appear, gives a clear sense of how much of the Irish countryside remains unrecorded until the right angle and the right season of dry weather finally brings it into view.