They are easy to walk past without a second thought, reading as natural undulations in the terrain. In fact they are the physical remains of an industrial process, charcoal production, that once operated on a considerable scale in this valley.

Charcoal was made by stacking wood on a levelled platform, covering it with earth or turf to restrict airflow, and burning it slowly over several days. The resulting product was a concentrated, smokeless fuel essential for iron-smelting and metalworking. The platforms here, known as hearths or pitstead platforms, number at least seventy-five on the northern and southern shores of the Upper Lake, with a further forty of similar dimensions recorded in the same general area. The oval shape and the careful levelling into the slope are characteristic of this type of feature across Ireland and Britain. References in earlier twentieth-century literature, including work by Ua Riain from 1940 and Healy from 1972, confirm that these features attracted scholarly attention well before industrial archaeology became a recognised discipline in Ireland.

What is quietly striking about the site is its proximity to Reefert Church, one of the early medieval ecclesiastical remains for which Glendalough is known. The overlap of monastic landscape and industrial activity in the same topographical zone raises questions about who was working here and when, questions the landscape itself does not easily answer.