Abstract
A palynological study was made of the marine sediments from the maximum transgression period of Oxygen Isotope Stage 7.3 at Miyakodai, Kakogawa (134°53′49″E, 34°48′43″N), in the Harima Plane facing the northeastern coast of the Seto Inland Sea, Japan. We revealed a temperate deciduous broad-leaved forest consisting of Fagus and Quercus subgen. Lepidobalanus, and pine forest spread out in the Miyakodai area in Substage 7.3. The sediments are tephrostratigraphically correlated to marine clay Ma 11 (2) of the Osaka Group. They yield pine and beech pollen in common, as well as very low values of Quercus subgen. Cyclobalanopsis, or other warm temperate elements. Nevertheless, the Miyakodai deposit differs from the typical Ma 11 beneath the Osaka Plain in the absence of Pseudotsuga pollen. By contrast, previous studies have shown that abundant Quercus subgen. Cyclobalanopsis occurs in the Takatsukayama clayey layer (Ma 9/Stage 11 equivalent) at Tarumi, Kobe, to the east of Miyakodai. These palynological differences are most likely the result of palaeoclimatological differences between the Middle Pleistocene interglacials. In this case Substage 7.3 was significantly cooler than Stage 11, even in its highest sea-level stand, which leads to the deposition of Ma 11 (2) marine clay.
