They are not the remains of dwellings or ritual structures. They are the workfloors of charcoal-makers, the flattened earthen stages on which colliers once stacked and slowly burned timber to produce the dense, smokeless fuel that industrial and domestic processes depended on for centuries.

Around seventy-five of these platforms have been recorded on the northern and southern sides of the Upper Lake and to the west and south-west of Reefert Church, one of the early medieval ecclesiastical ruins for which Glendalough is known. Each platform measures roughly nine metres by six, oval in shape, cut or built into the slope to create a level working surface. A further forty similar platforms were noted in separate surveys. The process they served, known as charcoal-burning or coaling, involved building a carefully constructed pile of wood around a central stake, covering it with turf and earth to restrict airflow, and then tending a slow, smothered burn over several days. The resulting charcoal was lighter to transport than raw timber and burned at the higher temperatures required for ironworking and smelting. The sheer number of platforms here suggests sustained, organised production rather than occasional local use, though the documentary record of who operated them and when remains sparse.

The platforms are spread at irregular intervals across the landscape, which means a careful eye is needed to pick them out. The area around Reefert Church and the western shore of the Upper Lake is accessible via the well-walked paths through the Glendalough valley, and the low earthen shelves become more legible once you know what to look for, particularly where the slope is steep enough to make the artificial levelling obvious.