These are burnt mounds, a type of prehistoric site found across Ireland and Britain, typically associated with the heating of water through fire-cracked stones. The general theory is that stones were heated in a fire, then dropped into a water-filled trough to bring it to temperature, for cooking, bathing, or industrial processes that remain debated. What is left behind is a characteristic crescent or horseshoe shape, the discarded heap of shattered, heat-fractured stone building up over repeated use around the edge of the trough.

The largest of the three mounds at Ballingowan is also the most northerly in the field. It measures 8.5 metres north to south and 7.5 metres east to west, though it survives to only 0.25 metres above the surrounding ground, barely a ripple in the landscape. Its trough, which opens to the west, runs 3.5 metres north to south and just one metre across, with its base sitting 0.45 metres below the crest of the mound. Where the top has been stripped back, boulder clay is visible beneath, and some burnt stone remains apparent among the disturbed material. Deep ploughing in 1997, following earlier land reclamation work in the area, has substantially damaged all three mounds. Michael Connolly recorded the site during a survey of the Lee Valley area carried out in 1996 and 1997, catching it at a moment when agricultural pressure had already done considerable harm.