In July 1975 an aerial photograph, catalogued as GSIAP W413, caught the traces of two concentric fosses, or ditches, forming a roughly oval enclosure approximately forty metres in diameter. The eastern side is cut off where a field fence has since been driven through it, erasing part of the outline that the ground still quietly preserves.

Cropmarks of this kind appear when buried features such as ditches or banks affect how vegetation grows above them. Soil that once filled a ditch tends to retain more moisture and nutrients, encouraging crops or grass to grow slightly taller and greener along those lines, while compacted or stony ground does the opposite. From ground level these differences are imperceptible; from altitude, and in the right season and light, they resolve into geometry. The double-fosse arrangement at Lackanamona suggests a defended or formally bounded enclosure, a form associated across Ireland with settlements, ritual spaces, or enclosed farmsteads dating anywhere from the Bronze Age through to the early medieval period. Without excavation, the precise date and function remain open questions.