The earthwork at Kilchreest is a roughly pear-shaped raised mound, running some 37 metres north to south and rising 3.75 metres above the surrounding ground. What catches the attention is not just its scale but its layered function: within its interior lies a children's burial ground, a cillín, the type of unconsecrated ground where, for centuries, unbaptised infants and others excluded from churchyard burial were interred without ceremony. The mound is encircled by a fosse and bank, a ditch and accompanying earthen rampart, running from the south-west around to the north-north-west, and the mound itself sits conspicuously higher than the bank, giving it an emphatic, almost deliberate presence in an otherwise flat landscape.

The site was noted by McCaffrey in 1952, though its origins are considerably older. The combination of fosse, bank, and raised interior mound places it within a tradition of early medieval earthwork construction in Ireland, where such features might indicate a ringfort, a burial monument, or a site repurposed across successive periods. That a children's burial ground came to occupy its interior is consistent with a broader Irish pattern: cillíní were frequently established at pre-existing archaeological features, places already felt to be set apart, marginal in the landscape or in communal memory. Here the surrounding bogland to the west, north, and east would have reinforced that sense of separation, making the mound a kind of island in the wet ground.