That discolouration, picked up on an aerial photograph, is what fulachta fia so often look like before anyone puts a trowel to them: a shadow in the ground, the residue of repeated burning and quenching over what may have been centuries.

A fulacht fia, the plural being fulachta fia, is a type of prehistoric cooking or processing site found across Ireland in considerable numbers, particularly in low-lying, waterlogged ground near streams. The typical arrangement involves a trough dug into the earth, a nearby source of water, and a mound of fire-cracked stone built up over time as heated rocks were dropped into the water to bring it to the boil. The broken, heat-shattered stones, dark with carbon and often mixed with charcoal, form the characteristic spreads that survive in the landscape long after any wooden trough or temporary structure has rotted away. The Ballytibbot example follows this pattern closely, positioned beside a stream in just the kind of marginal, damp ground that these sites tend to favour. Its dimensions, approximately eighteen metres in both length and width, place it firmly within the typical range for such monuments, which are most commonly dated to the Bronze Age, roughly 2000 to 500 BC, though some continue into the Iron Age.