琉球列島, 沖永良部島の完新世後期の高位海水準とその14C年代
1980 年 19 巻 4 号 p. 317-320
詳細
1980 年 19 巻 4 号 p. 317-320
Okierabu-jima of the Ryukyu Islands, which is a poly-terraced Pleistocene raised coral reef island, doesn't have a Holocene raised coral reef, but coastal erosional features showing higher sea levels in Holocene. The authors obtained some data indicating the period of one of the Holocene higher sea levels.
All radiocarbon dates concerning Okierabu-jima's Holocene sea-level changes are plotted on the date-height coordinates (Fig. 2). The paleo sea level between 5000 and 2000 y. B. P. lies above the broken line drawn from 6m below to 2.18m above the present sea level. The period of the highest sea level in Holocene seems to be about 3000 to 2000 y. B. P. in this island. Its height is presumably 2.4m a. s. l. derived on an average from heights of stacks and coastal benches in the almost all coasts of the island (Koba, 1974). Beach rocks were already formed at the landward extremity of the reef flat corresponding to the almost present sea level about 1300 y. B. P.
