These are the remnants of charcoal production, likely stretching back centuries, and they represent an industrial past that sits in striking contrast to the monastic serenity of the valley below.

Charcoal-making platforms, sometimes called hearths or pitsteads, were created by levelling a section of sloped ground to provide a flat surface on which timber could be stacked, covered with turf or soil, and burned slowly in low-oxygen conditions to produce the dense, carbon-rich fuel that was essential for iron smelting and metalworking. At Lugduff, more than seventy of these platforms have been recorded, each measuring roughly nine metres by six metres, arranged at irregular intervals along the northern and southern shores of the Upper Lake and to the west and south-west of Reefert Church, the ruined eleventh-century church associated with the monastic city of Glendalough. Their distribution across the valley suggests sustained, organised production rather than occasional use. The platforms were noted by Ua Riain as early as 1940, and a further forty comparable examples were recorded by Healy in 1972, pointing to a site of considerable scale.

The Upper Lake area of Glendalough is accessible on foot from the main valley, and the terrain around the lake shore and the slopes above Reefert Church is where these subtle earthworks can be found. They do not announce themselves; the platforms are low, grass-covered irregularities in the hillside, and a slow, attentive walk along the less-trafficked paths is the most reliable way to appreciate just how many of them there are.