It looks, at first glance, like a quirk of the terrain, a natural dip in the slope. But its position within the southern quadrant of a ringfort, and its geometry, suggest something more deliberate beneath the surface.

The depression is thought to represent a collapsed souterrain, an underground stone-lined passage or chamber built during the early medieval period, typically beneath or adjacent to a ringfort, the circular enclosed settlements that were the dominant farmstead type in Ireland from roughly the fifth to the twelfth century. Souterrains were used variously for storage, refuge, and ventilation of dairy goods, and were often constructed without mortar, relying on corbelled or lintelled stonework. This particular example may also have been quarried out at some point, which would help account for both the scale of the depression and the loss of whatever structural fabric originally lay beneath. The ringfort it belongs to occupies a position just off the hill summit, with open views sweeping from south through west to north, the kind of elevated, outward-looking placement that is characteristic of early medieval settlement sites across Munster.