Each one measures roughly nine metres by six, and they appear at irregular intervals on the northern and southern sides of the lake and to the west and south-west of the church. They are the remnants of a charcoal-making industry, the physical signatures of a process that was once widespread across wooded upland areas.

The platforms, sometimes called hearths or pitsteads, were levelled into hillsides to create a flat, stable surface on which a charcoal burn could take place. Wood was stacked in a careful mound, covered with turf or earth to control the air supply, and allowed to smoulder slowly for days at a time. The resulting charcoal was a vital industrial fuel, used in smelting and iron-working. At Lugduff, the sheer number of platforms, recorded as 75 in one survey and a further 40 in another, suggests this was not occasional or small-scale work. References to the site appear in scholarship going back to at least 1940, when Ua Riain noted the platforms, with later work by Healy in 1972 corroborating and extending that count. The proximity of so many sites to both the Upper Lake and Reefert Church raises questions about the period of activity and its relationship to the wider monastic and post-monastic landscape of Glendalough, though the surviving record does not firmly answer them.