They are easy to walk past without a second thought, mistaken perhaps for natural terracing or the remnants of some forgotten field system. In fact they are the traces of charcoal production, an industry that once required levelling the ground into flat working beds, known as hearths or pitsteads, where stacks of timber could be slowly smothered and burned over several days to drive off moisture and produce the dense, carbon-rich fuel that smelting and ironworking depended upon.

At least 75 of these platforms have been recorded on the northern and southern sides of the Upper Lake, with a further cluster to the west and south-west of Reefert Church, one of the early medieval ecclesiastical ruins for which the Glendalough valley is known. An additional survey identified around 40 similar platforms in the same general area. The concentration is striking. The presence of so many pitsteads in close proximity to a monastic site raises questions about the scale of industrial activity that supported, or perhaps operated alongside, the famous community here. Ua Riain noted the platforms as early as 1940, and the site was revisited by Healy in 1972, but the charcoal-making history of Glendalough remains considerably less discussed than its round towers and carved doorways.