They are the physical remnants of charcoal production, an industry that leaves an unusually legible mark on the landscape once you know what to look for.

Charcoal-making platforms, sometimes called hearth platforms or pitstead platforms, were created by cutting into a hillside or building up level ground to produce a flat, stable surface on which a charcoal burn could be managed. The process involved stacking wood into a carefully shaped mound, covering it with turf or earth to control the air supply, and then tending the slow burn over several days. The oval shape, here running to roughly nine metres by six metres, is characteristic of this kind of working surface. At Lugduff, researchers recorded seventy-five such platforms at irregular intervals along the northern and southern sides of the Upper Lake, with a further forty of similar dimensions noted separately. The concentration is considerable, suggesting sustained industrial activity rather than occasional or casual use. The site was noted by Ua Riain in 1940 and further documented by Healy in 1972, though the charcoal-making itself almost certainly pre-dates those records by a considerable period.

Reefert Church, near which some of the platforms cluster, is one of the early medieval ecclesiastical remains for which Glendalough is well known, and the proximity of industrial earthworks to such a site adds a layer of complexity to how the valley was actually used across the centuries. The platforms sit quietly in the same landscape as the monastic ruins, easy to overlook but telling a different story about the people who lived and worked there.