Measuring roughly ten metres east to west and six metres north to south, the spread consists of heat-shattered stones and charcoal-enriched soil, the characteristic signature of prolonged, repeated burning in a waterlogged setting.

The mound belongs to a class of prehistoric site known as a burnt mound, sometimes called a fulacht fia in the Irish archaeological tradition. The term is used for accumulations of fire-cracked stone, typically found beside streams or in marshy ground, that built up over time as heated stones were dropped into water-filled troughs to bring the liquid to a boil. The exact purpose of these sites, whether cooking, bathing, textile processing, or some combination of uses, remains debated, but they are among the most common prehistoric monument types in Ireland. What came to light at Derragh was recorded by Kiely in 2000, during ground preparation works ahead of a forest plantation. A second, related site of the same type lies approximately seventy metres to the north-west, suggesting that this corner of Cork was visited and revisited over time by people who knew the value of its wet ground.