Time range for accumulation of shell middens from Higashimyo (western Japan) and Kimhae (southern Korea) by AMS radiocarbon dating

Abstract

Numerous large and small shell middens have been reported throughout the world. An interesting question is when the huge and thick shell middens were formed, and how many years were required to build up the whole midden. Shell middens contain not only shell fragments but also organic substances such as bones, nuts, acorn, and plant residues, which are suitable substances with which to establish 14C chronology of the middens. We have conducted 14C dating on terrestrial and marine materials collected from two lowland shell middens, the Higashimyo site in Japan (the Earliest Jomon period) and the Kimhae site in Korea (the Proto-Three Kingdom period), to establish high precision 14C chronologies and determine the time required for shell accumulation. According to Bayesian analysis of 14C ages from terrestrial samples, accumulation of Midden No. 1 at Higashimyo (altitude from −1.1 to −2.3m a.s.l., Δd=1.2m) started at around 8050–7950cal BP and ended at 7950–7750cal BP, lasting for ca. 100calyr, while accumulation of Midden No. 2 (altitude from −0.5 to −2.0m a.s.l., Δd=1.5m) started at around 8050–7800cal BP and ended at 7800–7650cal BP, lasting for ca. 200calyr. Thus the Midden No. 1 was abandoned a bit earlier than Midden No. 2, but the time range for sediment accumulation overlaps each other. Accumulation at the Kimhae shell midden (altitude from 5 to 14m a.s.l., Δd=9m) started at around the middle of the 1st C cal BC and ended at around the middle of the 3rd C cal AD, lasting for ca. 250 to 300calyr.