Stone-lined field boundaries, low and half-buried, run across the hillside in patterns that speak of organised agricultural life at a time when this landscape was far more densely occupied than it is today. These are not the walls of recent memory but the remnants of a field system whose origins reach back centuries, possibly millennia, into the Atlantic fringe of Irish prehistory.

Slievemore is already known for the Deserted Village at its base, a long street of roofless stone cottages abandoned during and after the Great Famine of the 1840s, though some evidence suggests seasonal occupation, known as booleying, continued there into the twentieth century. The field system on the mountain itself belongs to a longer and less legible story. Achill and the surrounding area preserve some of the most extensive traces of prehistoric and early historic land use in the west of Ireland, where the thin soils and sparse later development have allowed ancient boundaries to survive above ground in a way that would be impossible in more intensively farmed regions. Field systems of this kind, defined by clearance cairns and low earthen or stone banks, often indicate sustained cultivation or pasture management across generations, laid down incrementally rather than planned all at once.