Each one measures roughly nine metres by six, and there are at least seventy-five of them recorded on the northern and southern shores of the lake alone, with a further forty similar examples nearby. They are the physical remains of charcoal production, and they mark this quiet valley as a site of considerable industrial activity at some point in its past.

Charcoal-making platforms of this kind, sometimes called hearths or pitsteads, were created by clearing and levelling a patch of ground where timber could be stacked into a cone, covered with turf or earth to restrict airflow, and burned slowly over several days. The resulting charcoal was lighter and more energy-dense than raw wood, making it the preferred fuel for smelting and metalworking. The oval shape and the relatively consistent dimensions of these Glendalough examples suggest a systematic, repeated process rather than occasional opportunistic burning. References to them appear in scholarship as far back as 1940, when Ua Riain noted their presence, and Healy returned to the subject in 1972, by which point forty comparable platforms had been catalogued separately. The sheer number of platforms points to an operation of some scale, though the precise period of activity has not been firmly established in the available record.

The platforms are distributed at irregular intervals across the landscape rather than arranged in any obvious grid or cluster, which suggests charcoal-makers worked wherever suitable timber was accessible. Reefert Church, a small Romanesque ruin associated with the monastic site of Glendalough, sits nearby, and the proximity of so much industrial evidence to the ecclesiastical remains is a quiet reminder that medieval monasteries were not purely contemplative places but often supported or depended upon craft and metalwork trades in their immediate surroundings.