This is a bivallate ringfort, meaning it was enclosed not by one but by two concentric earthen banks, a design associated with higher-status settlements in early medieval Ireland. The inner and outer banks are separated by a fosse, a wide U-shaped ditch cut into the earth, which would have made the whole enclosure a considerably more formidable proposition than its current, softened appearance suggests.

When surveyors recorded the site in 1971, the ringfort measured approximately 52 metres east to west and 50 metres north to south, making it a large example of its type. Even at that point, time and farming had taken their toll. The inner bank had been almost entirely reduced to a scarp, a low eroded face of earth, and was notably levelled along its western to north-north-western arc. A small stone quarry had been cut into that same western scarp, suggesting the earthwork was at some point treated as a convenient source of building material rather than a feature worth preserving. On the south-south-western side, a slight gap and a low causeway crossing the base of the fosse are thought to mark the original entrance to the enclosure, with the causeway measuring roughly 5.6 metres across and standing only about 0.3 metres high. The outer bank survives more visibly along the northern and north-eastern arc, though a modern gap has been made at the north-north-east, likely for livestock access. The interior carries a gentle south-facing slope.

The site commands good views to the north-east and west, which may partly explain why this particular hilltop was chosen. Ringforts of this kind were typically the farmsteads of early medieval families, the double-bank version suggesting the occupants held some degree of local importance. At Pearsonsbrook, what remains is the ghost of that original geometry, still traceable as earthwork and scarp, even as pasture and quarrying have worked steadily to erase it.