A long, narrow depression runs roughly east to west for nine metres, just over two metres wide, and then opens into a roughly circular hollow about two and a half metres across. The edges of both depressions show what appears to be the upper courses of drystone walling peeking through the turf, suggesting that the land has not simply subsided but has collapsed inward over a structure that was deliberately built below it.

What lies beneath is, in all likelihood, a souterrain, an underground passage and chamber of a kind commonly associated with early medieval Irish ringforts. Souterrains, which are stone-lined tunnels and rooms constructed beneath or within the banks of these enclosures, are thought to have served as cool storage spaces or places of temporary refuge. The ringfort here sits on a natural rise amid gently undulating pasture, with open views in every direction, the sort of position that would have made it both defensible and conspicuous in the early medieval landscape. The linear depression traces what would have been the passage, while the circular hollow at its western end corresponds to the chamber itself, still lying largely intact underground, its roof now thinned by centuries of settlement and weight above.