It is a cillín, the Irish term for an unconsecrated burial ground used for unbaptised infants, and for centuries such places occupied a painful margin between the living community and the Church. Children who died before baptism were denied burial in consecrated ground under Catholic ecclesiastical law, and so families interred them instead in these liminal spaces, often near old boundaries, ringforts, or simply in fields that had some older, half-remembered significance.

The enclosure at Brierfield is roughly quadrangular, measuring approximately forty metres north to south and thirty-six metres east to west, bounded by a stone wall. Inside, a number of small set stones mark what are almost certainly individual graves, though the overgrowth has long since obscured them. No inscriptions are recorded, and no names survive with the site. This anonymity is characteristic of cillíní across Ireland, where the act of burial was often carried out quietly, at night, by the family alone, without the formal rites that would accompany an adult funeral. The practice persisted in parts of rural Ireland well into the twentieth century, shaped by a combination of Church teaching, local custom, and the particular grief of parents who had little other recourse.