What is less well known is that the hill continues to yield new archaeology, not through excavation, but through geophysical survey, the technique of reading the ground's magnetic signature without ever breaking the surface. Among the features detected this way is a circular enclosure 23 metres in diameter, visible in the data only as a narrow, discontinuous band of heightened magnetic values, somewhere between half a metre and a metre wide. That faint signal is interpreted as the ghost of a slot-trench, the kind of narrow foundation cut used to hold a timber palisade upright, though the possibility that it was once a roofed timber structure has not been entirely dismissed.

What makes this particular enclosure quietly significant is its position in the sequence of things. The geophysical evidence indicates that it lies beneath a larger, 35-metre enclosure on the same western summit, and also beneath a feature known as St Patrick's Bed to the east. In archaeological terms, underlies means predates, and that stratigraphic relationship places this smaller enclosure earlier than both of those features. It may, according to the researcher Dr Roseanne Schot who compiled this work, be the earliest archaeological feature yet identified at Uisneach. Inside and around the enclosure, a significant number of pit-type features were recorded. One of the largest sits at roughly the centre of the circle, and to its north there is an arc of what may be post-pits, the kind of pattern that suggests some form of internal structure or organisation whose purpose remains, for now, a matter of interpretation rather than fact.