The paper deals with the relationship between the landform and crustal movement of the Ohyama River delta plain in the southwestern part of the Shonai Plain, and the depression zone on this delta plain. The results are summarized as follows:
The alluvial plain of the Ohyama River is composed mainly of delta plain. To the west this alluvial plain adjoins the Kamo moutains, and to the south Yakushidake and Sanbokura mountain blocks. The Akagawa floodplain, the eastern boundary of this alluvial plain, coincides with a tectonic line running from north to south, which divides the Shonai Plain into the eastern and the western parts. Judging from landform, alluvial geological structure, bedrock geological structure and gravity anomaly distribution, the author is certain that this delta plain corresponds to a trough between the tectonic line above and that at the east of Kamo mountains.
The trough forming movement has continued throughout the making of delta plain, and is partly reflected in the results of repeated precist levelling.
Moreover, the 10-15m contours on this plain show a depression zone in the same direction with the Kamo mountains.
Under this depression zone, a synclinal movement of the Kamigo formation, which comprises the eastern part of the Kamo mountains, has been continuing even after the formation of delta plain.
This movement has brought the undulation on the plain surface such as a down-warping with dimensions of 1-1.5km by about 9km.
According to the results of repeated precise levelling from 1956-1966, including the crustal movement caused by the Niigata earthquake, the bench mark located closest to this depression zone is still dropping.
Therefore, the author concluded that the depression movement of the Ohyama River basin is still going on in the recent geological time. The Ohdo River flows south-southwest to north-northeast on this depression zone.

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In the summer temperature distribution of Japan, the “north cool-south hot” anomaly pattern has been often recorded recently. Such a pattern is noteworthy from the viewpoint of climatic change. The object of this study is to clarify the regionality of August temperature variation in relation to the distribution of fronts.
In terms of correlation charts of August temperature (Fig. 2), the fluctuation pattern over Japan is synchronous in E-W direction, and it has “turning zones” crossing over Shikoku and over mid-Tohoku, where it changes abruptly in meridional direction. Such a pattern is extended in East Asia (Fig. 3), where the areas of northern and southern fluctuation patterns confront each other in Japan.
Temperature anomaly distribution in August is in close connection with appearance of fronts. Yearly frontal zone, i. e. discontinuous zone of temperature distribution, tend to appear along one of the above “turning zones” (Fig. 4). This indicates that the climatic frontal zone results in a discontinuous zone in the patterns of temperature fluctuation.
It is said, from the viewpoint of secular change, that the frontal zone moved southward in 1952, and the temperature lowered in northern Japan thereafter, while it remained unchanged in southwest Japan. Therefore the temperature gradient along the Japanese Islands became considerably steeps in 1950's (Fig. 6 and 7).
The surface frontal zone in August is closely related to upper westerlies (Fig. 8). The surface air temperature is connected with the general circulation through the fluctuation of frontal zone. Thus the situation of frontal zone can be regarded as a useful index for the climatic change.

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The Taiwan Low (T. L.) rises on the East China Sea near Taiwan Island in late winter and early spring, and often brings about considerable precipitation passing over the Pacific Ocean to the south of Japan. It is one of the important phenomena of winter climate of Japan, mainly influenced by winter-monsoon. In this paper, the distribution of precipitation brought about by the T. L. is studied in relation to its location and passage.
The results are summarized as follows;
1) The T. L. travels eastward mainly along two tracks: the northern corresponds almost with the current of Kuroshio, while the southern with the Pacific Polar frontal zone in winter (Fig. 1).
2) During the passage of the T. L. along the northern track, the T. L. is influential upon the South coast of Japan, but when it passes along the southern track it is little effective on Japan (Fig. 3).
3) The precipitation area brought about by the T. L. moves from west to east with its travelling eastward. The ordinary monsoonal precipitation pattern, appearing on the coast of Japan Sea in winter, is not seen during the passage of the T. L., and recovered after the T. L. reached further eastward (Fig. 4).
4) Three distinct patterns are found in Kii Peninsula, from the view point of large scale analysis of the regional distribution in precipitation brought about by the T. L. They have close connection to the location of the T. L. respectively and they are changeable one another as the T. L. passing by (Fig. 6, 7).

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