Erosion has cut back a low cliff edge to reveal a layer of shells sitting roughly thirty centimetres below the present ground surface, part of a shell midden that stretches for about ten metres in cross-section. A midden is essentially a prehistoric or early historic rubbish deposit, the accumulated debris of repeated meals, and shell middens in particular represent the remains of shellfish harvested over long periods from nearby coastal waters. What makes this one quietly arresting is the way it has come to light, not through excavation or deliberate investigation, but through the slow attrition of the coastline itself.

There are two such middens recorded on Corkbeg Island, and the one on the southern shore is among the more visibly legible. The shell layer is relatively thin, around four centimetres deep, but its horizontal extent and its clean exposure in the cliff profile make it readable as a distinct episode of human activity. The island sits in Cork Harbour, and its shores would have offered reliable access to shellfish over many centuries. Without excavation it is not possible to date the deposit precisely, but shell middens of this kind are found across Ireland from the Mesolithic period onwards, some of the earliest evidence of coastal communities making systematic use of marine food sources.