Wurm 氷期中の亜間氷期の高海水準について

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The altitudes of the coastal terraces, which are presumed to be formed about 30, 000 years B. P., are remarkably different at each locality. In the regions such as Scandinavia and Antarctica, which were covered by ice sheets during the Würm glaciation maximum, the altitudes of the “30, 000 B. P. terraces” are relatively high. This is probably due to the isostatic uplift with the reccession of the glaciers during the Post-glaciation. In the “crustal active zones”, such as the Circum-Pacific and East Africa, the terraces discussed here are situated at elevations from lower than-80 M to higher than +50 M above the present sea level namely, the variation of their altitudes is great. This great variation is believed to have been caused by the violence of the block-movement during the late Quaternary. In the “stable continents”, though the sea level of 30, 000 years B. P. lie below the present one at the mouth areas of the Mississippi and the Senegal rivers, they reached above the present one in regions such as the east coast of North America, India and the west coast of France. From these observations, it is summarized that the altitudes of the “30, 000 B. P. terraces” are high in the upheaval-areas, low in the subsidence-areas and intermediate in the stable areas, corresponding to the tendency of the crustal movement suggested from a geologic-geomorphologic point of view. Though these terraces have the great variation in the altitudes as above mentioned, most of them are higher than-30 M. Additionally, there are not a few localities indicating that these terraces were formed by the transgression. The sea level-change curves based on these facts from some areas show the rise of the sea level at about 30, 000 years B. P. Therefore, it is considered that the sea level was globally high at this time and that the “30, 000 B. P. terraces” will be found probably at many other coastal areas in addition to the reported ones. On the other hand, it has been recognized recently by studies of the paleotemperature that the relatively warm interval occurred about 30, 000 years B. P. in many areas of the world. Moreover, it has been reported that the glaciers considerably receded during this warm interval in many continents. These facts mean that the Würm interstade of about 30, 000 years B. P. was a global phenomenon and that the high sea level of that time can be explained generally by the glacio-eustatic theory, though the exact quantitative relationship between the sea level and climate still remains questionable.
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Wurm 氷期中の亜間氷期の高海水準について

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