Coral reef terraces on Yonaguni Island are morpho-stratigraphically divided into four units, from Terrace I to IV, in descending order. Among them, the lower two terraces (Terraces III and IV) were determined by α-spectrometric ²³⁰Th/²³⁴U dating to be correlative to oxygen isotope stages 7 and 5e, respectively. On the basis of the present height of Terrace IV, the amount of uplift since the last interglacial maximum, isotope stage 5e, is different for each small tectonic block of the island. For instance, the amount of uplift during the last 130, 000 years varies from 12m for the Sonai areas to 24m for the Kita-Bokujo area; these are adjacent to each other on the north coast.
The limestone that unconformably underlies Terraces IV is composed of two upward-shallowing sequences, each of which is typically built up with four types of limestone, (rhodolith limestone, Halimeda limestone, bioclastic limestone, and coral limestone, in ascending order). The give-up type of reef (Neumann and MacIntyre, 1985) can be recognized in such sequences. That is, coral limestone in the uppermost part of the lower sequence is formed as a give-up type of reef, because it could not catch up with a rapid rise of sealevel at the beginning of isotope stage 7. During the time of high sealevel stand in the penultimate interglacial, the coral reef may have grown laterally seaward. Such lateral growth of the reef deposited fore-reef sediments like Halimeda limestone and rhodolith limestone, on the bottom of the nearby insular shelf. As a result, the upper sequence is correlated with the reef limestone in the lower of the two sequences and may be assigned to the high sealevel stand in the oxygen isotope stage 9.
The last intergalcial reefal (coral) limestone generally occurs as thinner beds than those of the penultimate interglacial. Bioclastic limestone, Halimeda limestone, and rhodolith limestone deposited during isotope stage 5 are rare on Yonaguni Island. Terrace IV may be mainly depositional but partly erosional in origin, because typical examples of karst (e.g., pinnacles and dolines) are observed, and because its surface is partly collapsed to expose the underlying limestone, which is bioclastic limestone of the upper sequence formed during isotope stage 7.

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Numazawa volcano is a small caldera located in the southern part of the Northeast Japan Arc. Previous works have shown that this volcano has produced a pyroclastic flow deposit and a plinian pumice fall deposit, named the Numazawako Tephra (Nm-NM), at around 5ka. The existence of several tephra layers stratigraphically below the Nm-NM deposit has also been determined. The present authors have clarified that a series of eruptions from Numazawa volcano has produced tephra between 50-55ka preceding the Nm-NM eruption. This newly nominated tephra is named the Numazawa-Kanayama Tephra (Nm-KN). The purposes of this paper are (1) to present the petrographic properties, stratigraphic position, and distribution of this tephra, and (2) to discuss its eruptive age, volume of deposit, and relations with caldera formation history.
The Nm-KN around the caldera vent consists of several plinian pumice falls and a subsequent ignimbrite, which is partially welded. A volcanic clay fall deposit is found in the area close to the vent, suggesting that a steam eruption has occurred during the tephra eruption. The air fall deposit of the Nm-KN covers over 100km eastward of Numazawa volcano. In the Aizu Basin and on the flanks of Bandai, Azuma, and Adatara volcanoes, the Nm-KN is found as a plinian pumice deposit in most cases, and possible co-ignimbrite ash fall is observed. The Nm-KN is distinguished by its phenocrystic cummingtonite (n₂=1.656-1.665) hornblende (n₂=1.666-1.677), and biotite. The eruptive age of the Nm-KN is estimated at 50-55ka on the basis of its stratigraphic relationship with two well-dated tephras. These are Aso-4 (86-90ka) leveled below the Nm-KN, and DKP (50-52ka) just above. Calculated apparent eruption volumes of the Nm-KN are 1.4km³ for the plinian pumice deposit and 1.5km³ for the ignimbrite. It is most likely that the vent from which the Nm-KN originated was located at the present Lake Numazawa.

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Fluvial and marine terraces are distributed on the western and eastern sides of the Hakodate Plain, southern Hakkaido, and are divided into 5 levels, from terrace 1 to terrace 5 in descending order. Most terraces are of fluvial origin; however, terraces 1 and 2 on the southern part of the study area are marine terraces. Terrace 2, covered by tephras which include Toya volcanic ash of ca. 90-100ka, represents the last interglacial maximum of oxygen isotope stage 5e. The former shoreline height of terrace 2 at the west of the Hakodate Plain is ca. 80m, while it is ca. 50m at the eastern side. The lowest aluvial plain is underlain by marine deposits at least 25m thick. The upper limit of Holocene marine deposits, dated at ca. 6ka, is 0.6-2.1m above sea level on the eastern part of the Hakodate Plain and -0.8m along the coast, implying that the Hakodate Plain has been relatively stable during the last 6ka.
On the western margin of the Hakodate Plain, two prominent fault groups run nearly north-south: Oshima-Ono Fault on the north and Tomikawa Fault on the south. No fault is recognized on the east, however. These two fault groups are boundary faults between the hills underlain by early Pleistocene marine deposits and middle to late Pleistocene terraces on the west, and Holocene lowland on the east. These faults are represented as flexural scarps on terrace surfaces associated with reverse faulting, and are accompanied by rangefacing fault scarplets as antithetic faults. Progressive activity with a slip-rate of 0.2-0.9m/ka is observed on the main flexural scarps. Even range-facing scarps with a low slip-rate of 0.05-0.1m/ka show progressive deformation. The presence of thicker early Pleistocene marine deposits (ca. 600m) on the west of the plain, in comparison with those only 180m thick on the east, indicates that the Hakodate Plain has been under a compressive stress field and has been formed as an active fault-angle depression since the middle Quaternary, and that the western side of the fault has been absolutely uplifted.

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