But at the southern end of Little Saltee, something low and overgrown crosses the rocky ground: an earthen bank, or possibly the collapsed and grassed-over remains of a stone wall, cutting across a small promontory. It is the kind of feature that reads, tentatively, as a promontory fort, the type of enclosure, common along the Irish coastline, in which a headland is defended on its landward side by one or more banks and ditches, leaving the sea cliffs to do the rest of the work.

The complication is one of cartographic confusion. The headland actually marked on the Ordnance Survey Discovery map as the fort's location shows no visible sign of having ever been defended. It is the other promontory, the low rocky one at the island's southern tip with its ambiguous earthen feature, that looks more plausible as a candidate. Casey, writing in 2001, noted that a possible fort recorded for Great Saltee is not marked on the Discovery map at all, raising the likelihood that the two islands were mixed up somewhere along the way by the OS. Neither site had been formally visited and assessed at the time of that observation, which leaves both in a state of productive uncertainty: recorded, mapped, misidentified, and unresolved.