A midden is essentially a prehistoric or early historic rubbish deposit, the accumulated refuse of human meals and daily life, and the shells, bones, and pottery found within them can tell archaeologists a great deal about diet, trade, and settlement patterns. That oysters ended up here, well inland from the sea, suggests they were carried some distance, either as food, as a traded commodity, or both.

The deposit came to light during the archaeological investigations carried out along the route of the Cork-Dublin gas pipeline between 1981 and 1982. Large infrastructure projects of this kind, cutting long linear trenches across the countryside, have a history of exposing material that would otherwise remain buried and unrecorded, and this pipeline was no exception. The Kilmog midden, consisting of a number of oyster shells recovered from the topsoil, was documented by Sleeman in 1983. The shells themselves are modest evidence, but they are a reminder that even a thin scatter of organic material in disturbed ground can carry a quiet record of human activity.