It is not dramatic to look at, but it is quietly extraordinary: a layer roughly one to two metres thick of limpet and periwinkle shells, fragments of animal bone, and a scattering of fire-cracked stones, the compressed remains of meals eaten by people who lived here an unknown number of centuries ago.

A midden, in archaeological terms, is essentially a prehistoric rubbish heap, and they are among the most informative features a site can offer. The contents tell researchers what animals were hunted or kept, what shellfish were gathered from nearby shores, and how long a settlement may have been occupied. On Inishkea South, the midden is directly associated with a prehistoric house at the north-eastern end of the island, and it appears to overlie, or be partly incorporated into, a compact layer of brown soil roughly ten to fifty centimetres deep that may represent an earlier ground surface. Shells and animal bone are also loosely scattered across the interior of the house itself, suggesting either that waste was not always carried outside, or that the midden material has spread over time. The fire-cracked stones hint at cooking activity nearby, though their precise relationship to the midden layer is not fully resolved.

What makes the situation on Inishkea South particularly poignant is that the midden is only visible at all because the eastern edge of the house is eroding. The island, off the coast of County Mayo, is uninhabited, exposed, and subject to the kind of coastal processes that gradually unpick a site from the outside in. The layer is, in a sense, reading itself out into the open, one season at a time.