The existing field boundaries run in one direction; beneath them, the soil remembers something older, laid out on an entirely different axis.

The evidence comes from cropmarks, a phenomenon where buried ditches, banks, or walls affect the growth of crops above them, producing subtle variations in colour and height that only become apparent in aerial photography. In July 1989, a survey captured a regular pattern of rectilinear cropmarks at Ardglass, some running perpendicular to each other, spread across an area of roughly three hectares. The geometry is orderly enough to indicate a deliberate field system, one whose orientation bears no relationship to the patchwork of boundaries in use today. Whoever divided this land in straight lines and right angles was working to a different plan entirely, and whatever that plan was, it was eventually abandoned and overlaid by a later arrangement. Adjacent to the south-western edge of the cropmark pattern sits a circular enclosure, a separate but presumably related feature in the same buried landscape. Circular enclosures in Irish archaeology typically refer to the remains of a ringfort or similar enclosed settlement, suggesting that this was not just farmland but a worked and inhabited place.