The surface is uneven in a way that working farmland rarely is, and running across it is a low, curving scarp, a subtle ridge or bank tracing an arc through the improved grass. On its own it might pass for a natural undulation. From the air, though, the geometry becomes unmistakable.

What the ground holds here is the ghost of an enclosure, a circular or near-circular boundary of the kind commonly thrown up in early medieval Ireland as a ringfort, a farmstead defended by earthen banks and ditches. At Teernaboul, the surviving scarp measures roughly three and a half metres wide and a quarter of a metre high, so barely knee-height at its best-preserved point, and a second curvilinear feature lies some fifty metres to the west-northwest. The clearest evidence for the enclosure's full extent comes not from walking the field but from aerial photography: both the 2005 Ordnance Survey Ireland imagery and the 2013 Bing dataset show a cropmark tracing the circuit of a buried or heavily degraded boundary. Cropmarks of this kind appear when buried features affect how vegetation grows above them, with ditches often producing lusher, greener growth and banks producing thinner, drier strips, differences invisible at ground level but readable from altitude. The site sits on a south-west-facing slope, an orientation that would have made practical sense for an early settlement seeking shelter and sunlight.