In order to clarify paleoenvironmental changes during the late Holocene, we obtained core samples from eight sites in the Akkeshi Moor. Diatom assemblages from the cores were divided into three environmental flora groups based on their environmental characteristics as follows. Assemblage M was characterized by marine species, such as Biddulphia aurita, Cocconeis scutellum, Synedra fasciculata. Assemblage T was characterized by marine and brackish species Melosira sp. 1, Diploneis smitbii, Cocconeis scutellum and Paralia sulcata. Assemblage F was characterized by freshwater species Tabellaria flocculosa, Aulacoseira granulata and Eunotia spp.
Three paleoenvironmental stages of the moor were identified based on paleoenvironmental reconstruction of the diatom assemblage and by chronological correlation using radiocarbon dating and the tephra. The process at the marine transgressions and regression were compiled besed on the detailed lithological characteristics of the peat and mud deposits in Akkeshi Moor.
(1) Stage 1 (-ca. 2, 600yrs BP)
A long intertidal flat was formed from the mid to upstream area of the Chiraikaribetsu River, and a shallow bay was at its downstream area around 3, 000yrs BP. Subsequently, the upper half of the intertidal flat was infilled by marshy deposits due to the marine regression beginning at ca. 2, 600yrs BP.
(2) Stage 2 (ca. 2, 600-900yrs BP)
A small transgression occurred, and the relative sea-level reached its the highest stand (ca. +1m) over the last 3, 000yrs at ca. 2, 000yrs BP. The sea extended midstream beyond the preceding marshy area. After this transgression, relative sea-level again dropped below the present level and moor conditions prevailed extensively in the lowland again.
(3) Stage 3 (ca. 900yrs BP-)
There were fewer remarkable changes in sedimentary environments than were observed in the preceding stages. A transgression at ca. 600yrs BP, when the relative sea-level was at ca. +0.4m above the present stand, spread and inundated only the downstream area. After that, the existing Akkeshi Moor was formed.

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Ando-soils with a humic and thick A horizon are widely distributed in Japan. These soils are mostly derived from tephra materials, and recent studies make it clear that these humic and thick A horizons have developed upward cumulatively. Several factors, such as continuation of grassland vegetation, topographic stability, and a suitable climate, are considered to be necessary for the genesis of Ando-soils. However, Andosoils are only sparsely distributed in the Kinki district of central Japan. To elucidate the pedogenetic processes of Ando-soils in the Kinki district, with special reference to the origin of parent materials and their deposition mode, and the vegetational environment in the past, we researched three soils, Towano soil (Hyogo Prefecture), Aibano soil (Shiga Prefecture), and Shio-no-misaki soil (Wakayama Prefecture). These soils have black or dark-brown colored A horizons over 40cm thick. That of Towano soil is over 2m thick and has alternating deep black and slightly light black sub-horizons. Judging from these stratified component of sub-horizons, it is presumed that the Towano soil has a cumulative development process. Microscopic mineral analysis for the sand fraction and X-ray diffraction analysis for silt and clay fractions were carried out to investigate the origin of parent materials of these soils and their deposition mode. Plant opal and pollen were analyzed to reveal the past vegetational history.
Primary mineral composition of the sand fraction showed a mixture of tephra-origin particles (volcanic glass, etc.) and bedrock-origin particles (groundmass fragment of bedrock, etc.). All the horizons of each soil contained volcanic glasses which were mostly derived from at least two kinds of tephra, but volcanic glass contents had no correlation with carbon contents. Silt and clay fractions were dominated by quartz in all horizons of each soil. Among them, the quartz grains in Towano soil were thought to be derived from foreign materials like eolian dust. A large number of plant opal grains have accumulated in most horizons of each soil; they are more strongly weathered in the deeper horizons. From these results, it is concluded that the studied Ando-soils have developed upward cumulatively under the balanced accumulation of organic matter and mineral materials. The results of plant opal analysis and pollen analysis suggested that open site vegetation like a grassland or sparse forest was maintained on the Andosoils. The results mentioned above were generally in accordance with previous research in north-eastern Japan.

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A molluscan assemblage including warm water species such as Meretrix lusoria, Mactra veneriformis, Umbonium moniliferum, etc., found in the Hakodate Plain was dated 2, 400-2, 300yrs BP by the ¹⁴C method. This age is younger than the known warm Jomon transgression (Flandrian transgression) period. Based on the newly dated assemblage, three stages of Holocene warm assemblages are recognized from southern Hokkaido: 7, 500yrs BP, 4, 000yrs BP, and 2, 400-2, 300yrs BP. These stages are concordant with three periods of strong northward inflow of the warm Tsushima Current. Warm molluscan assemblages probably extended their geographical range to Hokkaido three times synchronously with strong inflow of the current.

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The Chinese Loess is one of the best targets for the study of paleoclimatic changes spread over the Asian continent for the last 2.5Ma. The information from the loess is important for understanding Quaternary paleoenvironmental changes. The formation of the Chinese Loess Plateau has a close relationship with the initiation of the monsoon climate. The aeolian dust observed around Japan and the northern Pacific has been transported by monsoon winds, and the source area can be found in and around the Chinese Loess Plateau. The most important factor which propelled paleoenvironmental study of the Chinese Loess is the surprising similarity between the initial magnetic susceptibility curve obtained from the loess section and the oxygen isotope fluctuation from the deep-sea sediments. Although the demonstration of a new proxy for paleoclimate from the land sediments was impressive, several important questions have been raised: why does the initial susceptibility fluctuate in the loess sections, and what are causes of enhancement of the initial susceptibility in the paleosols? These have been hot topics for the last tens year in the world's rock magnetic community. The initial susceptibility is not simply controlled by the abundance of strong magnetic minerals but is also controlled by the grain size distribution of each magnetic mineral. The increase in abundance of superparamagnetic grains (<100nm) in the paleosol enhances initial susceptibility, which is induced by a pedogenesis of the loess. Whether biotic or abiotic, the formation of superparamagnetic minerals has been debated. A wet and warm climate could be a common factor in the enhancement of the initial susceptibility of paleosols. It is now becoming possible to propose quantitative, robust model to restore the paleoenvironment on the basis of paleoprecipitation deduced from the initial susceptibility fluctuation.

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