A study on the seasonality of prehistoric shell collecting activities, using analysis of shells from the shell mound relics in Okbuk-ri, Yellow Sea coast of South Korea

Abstract

A shell mound of the Bronze Age was discovered in Okbuk-ri, Yellow Sea coast of South Korea. According to radiocarbon age dating for two entities of bivalve shell, Cyclina sinensis that were obtained in the shell mound, those were formed in the Bronze Age in 760~410 BC and 710~360 BC, respectively. According to oxygen isotope analyses of bivalve shell, the value ranges from -10.2~-4.8‰ and -9.8~-3.3‰ with 3.5 and 4.5 seasonal periods, respectively. Therefore the bivalve is though to have been spawned in the summer, lived during the winter and summer for a total of 3 years, and collected in early winter of its fourth winter. The other bivalve is thought to have lived during the winter and summer for a total of 4 years, and collected during its fifth winter. The research about various shell mounds distributed across the west coast also reported that shellfish gathering was concentrated in the winter and springtime during the year, and the results of this study corroborate the results of existing studies. Assuming isotopic equilibrium precipitation of the specimens, bivalves at the time inhabited and formed its shell in -6~-5‰ of water. Therefore, it is evaluated that shellfish gathering at the time mainly took place in the estuary of Geum River, where the water was a mixture of seawater and fresh water, instead of at the west coast, where there is little influence of freshwater. the Bronze Age in 760~410 BC and 710~360 BC, respectively. According to oxygen isotope analyses of bivalve shell, the value ranges from -10.2~-4.8‰ and -9.8~-3.3‰ with 3.5 and 4.5 seasonal periods, respectively. Therefore the bivalve is though to have been spawned in the summer, lived during the winter and summer for a total of 3 years, and collected in early winter of its fourth winter. The other bivalve is thought to have lived during the winter and summer for a total of 4 years, and collected during its fifth winter. The research about various shell mounds distributed across the west coast also reported that shellfish gathering was concentrated in the winter and springtime during the year, and the results of this study corroborate the results of existing studies. Assuming isotopic equilibrium precipitation of the specimens, bivalves at the time inhabited and formed its shell in -6~-5‰ of water. Therefore, it is evaluated that shellfish gathering at the time mainly took place in the estuary of Geum River, where the water was a mixture of seawater and fresh water, instead of at the west coast, where there is little influence of freshwater.