Archaeological Evidence for a Former Bay at Seaside, Oregon

Abstract

Cultural shell middens, a common feature of coastal landscapes, preserve a record of past human use of coastal resources and often provide important paleoenvironmental information. Molluscan remains from two shell midden sites, located 0.7 km from the modern Pacific coast at Seaside, Oregon, suggest the former presence of a small sheltered bay at this locality. The modern sand beaches in the Seaside area, stretching for 30 km southward from the mouth of the Columbia River, are exposed to high-energy surf where razor clams ( Siliqua patula) are today the only common bivalve. By contrast, over 90% of molluscan remains (by weight) recovered from the archaeological sites represent species that favor sheltered water. Geologic studies in the Seaside area have shown that the beach prograded some 2 km over the last 4 millennia. The midden evidence suggests that the progradation was accompanied by the infilling of a former bay.