Shell middens — the accumulated refuse of marine resource exploitation, consisting primarily of shellfish shells with associated bone, charcoal, and artifact material — are the most common type of early archaeological site along the coast.

These middens represent the deep accumulation of waste from generations of shellfish gathering, fish processing, and other coastal subsistence activities.

Their sheer physical mass — some coastal middens reach several meters in depth and cover large areas — reflects the intensity and duration of coastal resource exploitation.

The oldest well-dated shell middens on the Northwest Coast have produced radiocarbon ages extending back approximately 9,000 to 10,000 years, indicating human occupation of coastal areas from the early Holocene.

These sites document the antiquity of coastal settlement but do not typically preserve the human skeletal material needed for direct analysis of the ancient occupants.