Just west of Whitechurch church in Ballycullane, County Kildare, a circular boundary lies largely invisible at ground level, detectable only as a cropmark, the faint differential in plant growth that forms above buried features when soil moisture and nutrients vary along the line of a buried ditch. What the cropmark traces is the fosse, or defensive ditch, of an early ecclesiastical enclosure, the kind of roughly circular boundary that once defined the sacred and secular territory of an early Irish church site.

The enclosure was identified from an aerial photograph, reference GB89.AI.12, taken in 1989. Cropmark evidence of this kind tends to emerge in dry summers, when grasses and cereal crops above shallower, nutrient-depleted soil turn colour faster than surrounding vegetation, briefly printing the ghost of a buried feature onto the landscape. Circular ecclesiastical enclosures are closely associated with early medieval Irish Christianity, when monastic communities and local churches alike defined their precincts with a substantial ditch and sometimes an internal bank. The circular form distinguished these boundaries from later rectilinear land divisions, and many survive only as place name evidence or, as here, as buried traces readable only from altitude. The proximity of the enclosure to Whitechurch church, a recorded monument in its own right, suggests the two features are related, the cropmark preserving the outline of the original early Christian precinct within which the later church was eventually built.