The collapse of a souterrain's roofing stones over centuries often leaves exactly this kind of subtle ground-level scar, easy to overlook, harder to explain away once you know what you are looking at.

The feature sits inside a ringfort, the circular enclosure of earth or stone that was the most common form of rural settlement in early medieval Ireland, used roughly between the sixth and twelfth centuries. Souterrains were frequently built within such enclosures, their entrances concealed inside dwelling areas. The precise history of this particular example at Turin is not documented in detail, but the association of underground structure with ringfort follows a pattern found across the country, most densely in the northern and western counties. The site was recorded in D. Lavelle's archaeological survey of the Ballinrobe district, published in 1994 by the Lough Mask and Lough Carra Tourist Development Association, which catalogued the remarkable concentration of prehistoric and early medieval remains in this part of Mayo.