What lies beneath the turf is a fulacht fia, a type of prehistoric cooking site found in enormous numbers across Ireland, particularly in low-lying or marshy ground. The term refers to a mound of heat-shattered stone, the accumulated debris of a process in which rocks were repeatedly heated in fire and dropped into a water-filled trough to bring the water to a boil. The burnt and cracked stones, useless after a few heatings, were simply discarded to one side, building up over time into the distinctive horseshoe-shaped mound that archaeologists now recognise across the Irish countryside.

Fulachtaí fia are generally associated with the Bronze Age, roughly 1500 to 500 BC, though some examples have returned earlier or later dates. They are among the most common archaeological monument types in Ireland, yet their precise purpose has been debated for decades. Cooking is the most widely accepted explanation, with experimental archaeology having demonstrated that a trough of water can be brought to a boil and maintained long enough to cook a joint of meat using this method. Other suggestions have included bathing, textile processing, and brewing, and it is possible that different sites served different functions at different times. The Barleyhill example, sitting in open pasture in north Cork, survives as a grass-covered spread rather than a clearly defined mound, which suggests either that the original deposit was not especially substantial or that years of agricultural use have reduced and dispersed the material.