They are not the remains of dwellings or ritual enclosures, but the physical trace of charcoal production, an industry that once required the careful construction of flat, cleared hearths where stacked timber could be slowly smothered and burned under a covering of earth and turf. Each platform, roughly nine metres by six metres, was purpose-built to support a charcoal clamp, and the sheer number of them suggests this was no casual or occasional activity.

Recorded sources note at least 75 such platforms positioned at irregular intervals along 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 stone churches from which the Sevenchurches valley takes its name. An additional group of around 40 comparable platforms was also documented. References go back at least to 1940, when Ua Riain noted the features, with later work by Healy in 1972 adding further detail. Charcoal was essential to early and medieval metalworking, providing the sustained, intense heat needed for smelting and smithing, and the proximity of this site to the monastic settlement at Glendalough raises intriguing questions about the relationship between industrial production and the community it may have served.