At Farranyharpy in County Sligo, one entry describes a grass-covered rise barely the size of a large dining table, measuring somewhere between two and a half and three metres across and standing just thirty centimetres high. It is composed of earth and stone, and nobody is entirely sure what it is. That frank uncertainty is, in its own quiet way, rather interesting.

The mound sits on a gentle west-facing slope in pastureland, immediately to the south-west of a cashel, which is a stone-walled enclosure of the kind used in early medieval Ireland to define and defend a farmstead or settlement. The surrounding ground is uneven and disturbed, and traces of an old field system run through the area. It is that context which makes the small rise so difficult to categorise. It may be a fragment of a ruined field boundary, a low wall so thoroughly collapsed and overgrown that only a slight swelling in the turf remains. Equally, it may be a field clearance heap, the accumulated result of generations of farmers lifting stones from their land and piling them at the margins. Both explanations are mundane, agricultural, entirely plausible. Neither can be confirmed.