The authors discuss the Holocene sea-level changes in the Sendai Coastal Plain. This plain is considered to have been rather stable as compared with other alluvial plains in Japan, especially during the Holocene. The consideration of geomorphology (Fig. 1) including underground (Fig. 2) and submarine geomorphology, stratigraphy (Fig. 3), pollen (Figs. 7 and 8) and diatom analyses of alluvial beds and radiocarbon dates (Table 2) leads the authors to conclude that the Holocene sea-level changes in the Sendai Coastal Plain can be presented in Fig. 10, and divided into two phases.
The first phase is characterized with rapid sea-level rise up to 8 meters below present sea-level. Shell beds (Table 1) 8 meters below present sea-level dated 7, 515±200¹⁴C y. B. P. suggesting that the water in Sendai Bay was warmer than at present. The second phase is from 7, 500¹⁴C y. B. P. onwards, a phase characterized by rhythmic fluctuations of the sealevel. The amplitude of these fluctuations is less than 2 meters, each fluctuation taking place over a period of 1, 000 to 1, 500 years. The sea-level apparently fluctuated several tunes, forming four beach ridges from inland one to seaward ones parallel to the present coastline.
In contrast with former studies, the authors could find no strong evidence in favour of the high sea-level known as the “Jomonian Transgression”, even if the authors assumed relative subsidence, caused only to the east of Nagamachi-Rifu Line (Fig. 9).