The one at Ballygarriff in County Mayo is typical of the type in its basic form: a low, kidney-shaped or horseshoe mound of fire-cracked stone and dark, charcoal-flecked soil, usually found close to a water source. They date most commonly to the Bronze Age, roughly 1800 to 800 BC, and are known in Irish archaeology by the term fulacht fiadh, a phrase that loosely translates as cooking pit of the wild. The standard interpretation is that people heated stones in a fire, then dropped them into a water-filled trough to bring the water to a boil, using the trough for cooking meat. The spent, shattered stones were then raked aside, and over time that discard heap became the mound itself.

What makes burnt mounds compelling as a category is how little agreement there is about what they were actually for. The cooking explanation is plausible and has been tested successfully by experimental archaeologists, but alternatives have been proposed over the years, including use as saunas or sweat lodges, for textile processing, or for brewing. Most burnt mounds were probably used repeatedly over long periods, and a single mound might represent many generations of activity rather than one episode. The example at Ballygarriff sits within a county that has a notably high density of such monuments, a reflection in part of Mayo's wet, boggy terrain, which both preserved the organic material within the mounds and kept marginal land from later intensive agriculture that might otherwise have destroyed them.