They were only noticed at all because aerial photographs taken in July 1989 revealed them as maculae, the faint soil discolourations that show up in cropmarks when conditions are right. Scattered apparently at random across the field, with six arranged in a loose northwest-to-southeast line, the pits share the same ground as two enclosures and a circular enclosure, suggesting a site of some complexity.

Four of the pits were investigated by excavator Martin Doody in the mid-1990s, and their dimensions alone give a sense of scale. Pit F36 was nearly three and a half metres across and nearly a metre deep, with a broad U-shaped profile; post-holes cut into its base, along with a foundation trench, hint that something structural once stood over it or inside it. A second pit, F43, was dug directly into F36 after the first had silted up, its fill containing minute charcoal fragments and a single piece of iron slag. Pit F163, steep-sided and irregular, yielded a radiocarbon date from its basal fill placing it somewhere between the mid-fifth and late sixth centuries AD, though Doody himself cautioned that inconsistencies across the site made it unwise to treat that date as definitive. Pit F180 had an unusual pointed base and sides that undulate rather than cut cleanly, its fill composed entirely of natural silt. What none of the four investigated pits showed was any clear evidence of storage, the most obvious explanation for large, purpose-dug holes. Two had features at their bases suggesting overhead structures of some kind, but the function of the group as a whole remains genuinely uncertain. Doody's conclusion was simply that at least some of these large pits probably represent the earliest activity on the site, predating the enclosures nearby. Similar cropmark patterns have been recorded at Ballycushen, not far away, which suggests this kind of feature may be less isolated than it appears.