The deviation is slight, barely noticeable on the ground, but it follows the southern edge of something far older, a roughly circular enclosure about 46 metres across that has not been visible as an upstanding earthwork for a very long time. The enclosure survives now only as a cropmark, a trace legible from the air when differential soil moisture causes crops to grow unevenly over buried features beneath.

The site at Joinersfolly came to light through an aerial photograph taken on 16 July 1971, part of the Cambridge University Collection of Aerial Photography. That single image identified not one but three enclosures in the area. This particular example is defined by a fosse, a defensive or boundary ditch dug around the perimeter, and it sits within a small cluster of related features: a ring-ditch, which is a circular ditched monument often associated with prehistoric burial, lies roughly 70 metres to the south, and a second enclosure of similar type sits about 80 metres to the south-west. Circular enclosures of this kind are common across Ireland and can date from the Bronze Age through to the early medieval period; without excavation it is impossible to say more precisely when this one was in use or what it contained.

What makes the field boundary detail particularly interesting is what it implies about landscape memory. Whoever laid out that boundary at some point in the post-medieval period was either working around a feature still partly visible then, or following a much older land division that itself respected the enclosure. The ground has since been levelled, the ditch filled, and the circle erased from ordinary sight, but the kink in the hedgerow remains as an inadvertent record.