They are easy to miss, and easy to misread; the untrained eye might take them for natural terracing or the remnants of forgotten field systems. In fact they are the physical traces of charcoal production, the kind of industrial activity that once accompanied ironworking across upland Ireland and Britain.

Charcoal was made by stacking and slowly burning wood under a carefully managed covering of earth and turf, a process that required a level working surface on otherwise uneven ground. The platforms, each roughly nine metres by six metres, were cut or built up on the slope precisely to create that surface. At Glendalough, sources from the mid-twentieth century recorded a remarkable concentration of them: seventy-five oval platforms distributed at irregular intervals along the northern and southern shores of the Upper Lake and to the west and south-west of Reefert Church, with a further forty similar platforms noted separately. Reefert Church itself is a small Romanesque ruin within the monastic complex, and the proximity of so many platforms to it suggests that charcoal production was at some point an organised and sustained activity in this part of the valley, though the precise period of use remains uncertain from what is recorded.