Eroding from the base of an earthen scarp roughly a metre high, a layer of oyster shells traces a line of about twelve metres along the tideline, its upper surface threaded with lenses of dark, charcoal-rich soil. This is a midden, a term for the accumulated refuse of a settlement, essentially a prehistoric or early historic rubbish deposit, and what it preserves here is a quiet record of people eating shellfish on this shore, building fires, and leaving the evidence behind in a way that the ground has held onto ever since.

Inishcottle is a drumlin island, one of the rounded, egg-shaped landforms left by retreating glaciers, lying close to the mainland in the inner north-eastern reaches of Clew Bay in County Mayo. Clew Bay is famously thick with such islands, and many of them carry traces of long habitation, given how readily they offered fresh water, grazing, and access to the sea's resources. The oyster shells concentrated here, some thirty centimetres deep at their thickest, suggest sustained and repeated use of the shoreline rather than a single occasion. The charcoal mixed into the upper layers indicates cooking or burning nearby. The eastern end of the deposit is already poorly preserved, with short sections eaten back by tidal action, and the rest is partly obscured by overhanging vegetation and collapsed material from the scarp above.

The site sits at the base of a scarp topped by a post and wire fence at the field's northern boundary, visible where the earthen face meets the gravelly shore. Tidal erosion is gradually exposing more of the layer, which means the section is clearest after storm activity or high tides have cleared loose material, though the same processes are also responsible for its slow destruction at the eastern end.