Each one measures roughly nine metres by six, and together they represent what was once an organised industrial operation: the making of charcoal. To produce charcoal, woodcutters would construct a carefully stacked mound of timber on a level platform, cover it with earth and turf to restrict airflow, and burn it slowly over days. The platforms, sometimes called hearths or pitsteads, were levelled into the hillside to keep the mound stable during firing. That so many survive here, at irregular intervals along the northern and southern shores of the Upper Lake and to the west and south-west of Reefert Church, gives some sense of the scale of production this valley once supported.

The platforms were documented in two separate surveys. Ua Riain, writing in 1940, recorded 75 of them; a later study by Healy in 1972 noted 40 platforms of a similar type. Whether the two accounts describe overlapping or distinct groupings is not entirely clear, but taken together they point to a site of considerable extent. The proximity to Reefert Church, a Romanesque ruin associated with the early monastic settlement of Glendalough, raises questions about the relationship between the monastery and this kind of woodland industry. Early Irish monasteries were often significant economic enterprises, and charcoal production, which required both managed woodland and a reliable demand for fuel, would have fitted naturally into that world. No precise dating for the platforms is given in the available records, so the question of exactly when they were in use remains open.