These are the remnants of charcoal production, an industrial process that once shaped the landscape here just as surely as any monastic building. Each platform, roughly nine metres by six, was levelled into the hillside to create a flat working surface where timber could be stacked into a carefully constructed mound, covered with turf or soil, and burned slowly over several days to drive off moisture and volatile compounds, leaving behind the dense, high-carbon charcoal needed for metalworking and smelting.

Around seventy-five of these platforms have been recorded at irregular intervals along the northern and southern sides of the Upper Lake and to the west and south-west of Reefert Church, one of the smaller Romanesque churches within the Glendalough monastic complex. A further forty platforms of a similar form have also been noted in the area. The concentration around Reefert is particularly interesting given the church's association with the kings of Leinster, though the platforms themselves speak less to ecclesiastical life than to the practical, often overlooked industrial activity that supported medieval and early modern communities. The scale of the operation implied by so many surviving platforms suggests this was not casual or occasional work but something carried out repeatedly, season after season, by people whose names are not recorded anywhere.