It is modest in what survives, roughly 2.3 metres long and 1.8 metres wide at the exposed section, but the construction method it reveals is quietly sophisticated. Layers of large brushwood were laid lengthwise on top of smaller brushwood, which was itself supported by a lower course of transverse brushwood running northeast to southwest. That deliberate layering, coarse over fine over cross-grained, is the signature of a structure built to distribute weight across unstable, waterlogged ground.

Peatland platforms of this kind are found at various points across the Irish midlands, where people needed to move through or work in boggy terrain that would otherwise be impassable. Some served as the foundations of trackways; others appear to have been fixed working surfaces, perhaps for fishing, fowling, or reaching deeper water. The Derryoghil example does not survive in enough extent to say with certainty which purpose it served, but the engineering logic is the same in either case: exploit the flexibility and buoyancy of brushwood to create a stable footing where there is none naturally. The bog itself, by sealing the wood in cold, acidic, oxygen-poor conditions, preserved what would otherwise have rotted away within a few seasons of its construction.