On Acaill Bheag, the remains of an ancient field system survive, a network of boundaries, walls, or earthworks laid out by farming communities at some point in the distant past to divide and organise the land around them. Field systems of this kind are among the quieter categories of archaeological monument, easy to overlook precisely because they look, at first glance, like nothing more than low ridges or overgrown lines in the grass.

Field systems in the west of Ireland range enormously in age. Some, preserved beneath blanket bog, date to the Neolithic or Bronze Age, their boundaries only becoming visible where peat has been cut away. Others belong to the medieval period or later, reflecting the rhythms of rundale farming, a pre-Famine system of communal land use in which strips and plots were periodically redistributed among families in a townland. Without more detailed survey information, it is not possible to say with confidence which period the Acaill Bheag field system belongs to, or how extensive it is, but its existence on a small island off an already remote coastline gives it a particular quality. Someone, at some point, thought it worthwhile to mark out and manage this ground, to make it productive or at least legible as territory.