Aerial photographs taken in July 2006 reveal a cropmark suggesting a circular enclosure, possibly multivallate, meaning it may have been defined by more than one concentric bank or ditch. Cropmarks form when buried features affect how crops grow above them: buried ditches retain moisture and produce lusher, taller growth, while buried walls or compacted ground do the opposite, leaving paler, thinner strips. From the air, these subtle differences in crop colour and height can outline structures that are entirely invisible at ground level.

The site at Ballyguile Beg has not been excavated, and its precise date and function remain uncertain. Multivallate circular enclosures of this kind are often associated with the later prehistoric or early medieval periods in Ireland, when ringforts and their more elaborately defended cousins were a common feature of the agricultural landscape. A multivallate example would have required considerably more labour to construct than a single-ditched enclosure, which may point to a site of some local importance, though without excavation that remains speculative. The cropmark was identified by Michael Moore during aerial survey work, a method that has revealed a significant number of previously unrecorded sites across Ireland, particularly in areas of arable farmland where ploughing has gradually reduced earthworks to nothing at the surface.