In a tilled field in Geraldine, Co. Kildare, a circle roughly ten metres across betrays itself only from the air. No mound, no stone, no visible earthwork remains at ground level; what survives is a cropmark, a faint signature written in the differential growth of crops over a back-filled fosse. A fosse, in this context, is simply a ditch, one that was once dug in a ring and has since been deliberately or gradually filled in. The soil within a filled ditch retains moisture differently from the undisturbed ground around it, and in the right season that difference shows up in the colour and height of whatever is growing above it, invisible to anyone walking the field but legible to anyone looking down.

The circular form, spotted on aerial imagery and communicated by P. Reid, is thought to be a ring barrow, a type of prehistoric burial monument in which a central mound or flat grave was enclosed by one or more circular ditches. These monuments are found across Ireland and Britain and are generally associated with the Bronze Age, though some examples date earlier or later. The Kildare example is tentative; the qualifier "possibly" matters here, since cropmark evidence alone, without excavation, cannot confirm what lies beneath or how old it is. What the aerial view does suggest is a coherent circular feature that fits the morphology of such a monument, and in a county with a well-documented prehistoric landscape, that is enough to warrant attention.