The field system at Cappagh sits on a south-west-facing slope above the valley of the Sheen River, arranged in a rectilinear pattern that covers an area of roughly 110 metres by 100 metres. The walls themselves are modest in scale, around 0.6 metres thick and 0.5 metres high, built in the drystone tradition, meaning without mortar, relying entirely on the weight and fit of the stones. Most have collapsed, but they still protrude above the surrounding peat, and at least one enclosed field remains legible: an irregular quadrilateral with sides measuring approximately 40, 40, 20, and 35 metres.

What makes the site quietly arresting is how the peat has both preserved and obscured it. The encroachment of bog over agricultural land is a recurring pattern across upland Ireland, and it tends to indicate that a farming community worked land that was later overwhelmed, either through climatic deterioration, soil exhaustion, or depopulation. The walls here run on east-west and north-south axes, suggesting a degree of deliberate planning rather than ad hoc enclosure. Just to the west, more recent field boundaries are still in use, which places the ancient system in an odd kind of dialogue with the working landscape around it, the old geometry half-buried, the newer one still functional a short distance away. The rough commonage setting means the site sits in open, unenclosed grazing land, adding to the sense that this particular patch of ground has cycled between uses across a very long stretch of time.