Each one measures roughly nine metres by six, cut into the hillside at irregular intervals on the northern and southern lake shores and to the west and south-west of the early medieval Reefert Church. They are the remains of a charcoal-making industry, and they survive in unusual numbers.

The platforms are what woodcutters once called hearths or pitsteads, levelled surfaces on which carefully stacked timber was covered with turf or earth and slowly smouldered over several days. This process, known as charcoal burning, drove off moisture and volatile compounds, leaving behind a lightweight carbon fuel suitable for smelting and smithing. The Glendalough valley, with its abundant oak woodland and proximity to iron ore deposits in the Wicklow hills, was well suited to this kind of production. Ua Riain noted the existence of these features in 1940, recording around 75 platforms, while Healy's later survey in 1972 documented a further 40 of similar character, suggesting the industry operated at considerable scale across the area over time.