What survives at Duncummin is a field system of broad, shallow channels, each averaging about 4.2 metres wide but only 0.3 metres deep, marking out individual plots that run to roughly 30 by 40 metres apiece. The fields are mostly rectangular, though curving sections appear to the north-east and west, and the whole arrangement has been laid out with clear awareness of what was already there.

What makes the site unusual is the density of older monuments embedded within it. The field system wraps around a ringfort, a type of enclosed farmstead common in early medieval Ireland, typically defined by one or more earthen banks, as well as a possible moated site to the north, a form of defended residence associated with Anglo-Norman settlement from the late twelfth century onward. Interspersed throughout the visible extent of the fields are at least thirteen ring-barrows, low circular earthen mounds used as burial monuments, suggesting that whoever laid out these channels was farming land already marked by the dead. To the north-east of the ringfort, a pattern of ridge and furrow is also visible, the corrugated surface left by repeated ploughing in long parallel strips, with individual ridges between 1.4 and 2 metres wide and raised only 5 to 10 centimetres above the furrows. This ridge and furrow respects both the field channels and the older monuments, pointing to a landscape that accumulated its layers carefully, each phase of use reading and responding to what came before.

The site is best preserved around the ringfort, where the curving field boundaries are clearest and the relationship between the various features is most legible from the ground. Because the pasture is level and wet, the shallow earthworks that define the channels and the faint corrugations of the ridge and furrow show up most clearly in low winter or early spring light, when shadows are long and the grass has not grown to obscure the slight changes in relief.