A midden is, in essence, an ancient rubbish heap, typically a dense accumulation of shellfish remains, animal bones, ash, and discarded tools built up over years or centuries of habitation. What makes these sites remarkable is precisely their ordinariness. They are the accumulated debris of daily life, and in their layers archaeologists can read diet, season, trade, and the slow rhythms of coastal settlement with unusual clarity.

Middens are found all along the Irish coastline, and those in County Mayo sit within a landscape that has been inhabited since the Mesolithic period. The county's Atlantic seaboard offered rich pickings in shellfish, particularly oysters, limpets, and periwinkles, and communities returned to productive coastal spots generation after generation, leaving behind deposits that can reach considerable depth. The Irish name An Chloich Mhóir, meaning roughly "the big stone", suggests a local landmark that would have oriented people in this landscape long before modern placename conventions took hold. Beyond that, the specific history of this particular midden remains undocumented in publicly available sources at present.