A radiocarbon dating analysis clarified that the latest accumulation terraces, which were found at eight river-basins in the Ou and the Dewa mountains (fault and fold mountains in the northern Japan), were simultaneously completed around 20, 000yr B. P. At the age of the terrace completion, the polar frontal zone began to recede to the present position, and subsequently caused a substantial increase in heavy-rainfall frequency due to a typhoon attack even in the northern Japan.
Detailed field survey and tephrochronological analysis for the Kariya river-basin in the upwarped Kitakami mountains, located in almost the same latitude as the Ou and the Dewa mountains, revealed that the latest accumulation terrace was also completed around 20, 000yr B. P. Simultaneity of the terrace formation regardless of their great geomorphological difference among those mountains described above, proved that a great increase in the heavy-rainfall frequency was primarily responsible for the initiater of the accumulation terrace formation. Accordingly, it was safely concluded that the formation of the latest accumulation terraces occurred around 20, 000yr B. P. by the climatic change, not crustal movements in the northern Japan.
A sizable volume of previous papers concerning the accumulation and the erosional terraces formed in the last 20, 000 years throughout Japan, was intensively reviewed, and the terrace distribution was mapped out. Consequently, it was confirmed that the formation of the accumulation terraces surely extended to the northern to central Japan, and that it commonly accompanied the erosional terrace formed at latest by 10, 000yr B. P. This accumulation-erosional terrace association characterized the river-landform development during the last 20, 000 years.
In the southern Japan, only the erosional terrace without the accumulation terrace was identified at the Miya, the Ishite and the Mimi river-basins. Since fossil periglacial landforms in the last Glacial time, widely distributed in Japan, are known to be closely associated with the accumulation terrace, the accumulation-erosional terrace association was plausible to be formed in the southern Japan, and the erosional terrace, therefore, was considered to be the counterpart of the terrace association.
In addition to the terrace association in the last 20, 000 years, if a similar key landform is detected in the landforms before 20, 000yr B. P., there is a great possibility to develop a new topographical analysis method.

View full abstract

The purpose of this paper is to evaluate the spatial and temporal influences of economic level at the prefectures of origin and destination on internal migration movements by using the unconstrained gravity model (equation 3). The data used covers gross inter-prefectural migration flows during the period of rapid economic growth, 1955-72. The data of personal income per capita are used as proxies for regional economic levels.
Unfortunately, statistical data for migration are affected by the size of statistical areas. Here, statistical data are standardized by equation 4. The standardized data (similar to velocity of migration), however, are not equivalent in terms of their representation because the size of origin and destination prefectures for each sample is varies. Here, the number of samples is also corrected according to the size of origin and destination prefectures by equations 6 and 7.
Firstly, the entire inter-prefectural migration flows are analyzed and the conclusion made is that (1) both incomes at destinations and origins have a positive effect on migration; (2) incomes at destinations are considered to be more important factors than those at origins, but those efficiencies are proved to be in decline year by year; and (3) for incomes at origins, their absolute effects have no remarkable changes, but as the effects of incomes at destinations decline, their comparative effects increase.
Next, the entire inter-prefectural migration flows are divided into: (1) two groups by income difference between destinations and origins; and (2) four groups by metropolitan and non-metropolitan types. Each group of migration is analyzed by the gravity model. Those results are shown in figures 4 and 7, which are excluded in this summary.
Finally, the out-migration flows for each of the 46 prefectures are analyzed by the origin-specified model (equation 8). It is found that, in each given year, for those out-migrants from less-advanced regions, destination income elasticities are very high. As for those from middle-advanced regions, those elasticities are lower though still in the plus, while for those from advanced regions, the elasticities are very low or turn to minus. Here, the temporal changes of these elasticities for each prefecture show that the elasticities increase in those less-advanced regions located mainly in the peripheral areas of Japan, while decrease in those advanced regions located in Japan's core area. The incomes which cause the elasticities to become zero are defined as critical incomes and their changes are shown in figure 10. Similarly, in-migration flows for each of the 46 prefectures are also analyzed by the destination-specified model (equation 9).

View full abstract

The aim of the Agricultural Basic Law (1961) was to increase farm income by scale enlargement and farm mechanization. In Hokkaido, over the past three decades, upland farms were mechanized and management scale was enlarged. On the contrary, most farmers in Honshu (the main island) became part-time farmers. The law therefore affected the two regions in different ways.
In Hokkaido, mechanization also made it possible to improve land productivity. Deep ploughing by tractors, which replaced horses, allowed more fertilizer input. Mechanization of pesticide and insecticide application helped to extend the growth period. This mechanization proved to be labor saving and brought about increased land productivity. The productivity increase was particularly visible in potato production. The yield per hectare has nearly doubled over thirty years.
Tokachi and Abashiri are the two main potato growing areas in Hokkaido. Both areas, at the beginning of the mechanization phase, had showed the same land productivity. Through mechanization, Abashiri realized higher productivity increases than Tokachi. Tokachi shifted its emphasis from potato starch production to the production of potatoes for home culinary and for processing. Most of the varieties in Tokachi were changed to early-ripening ones. Farmers in Tokachi succesfully produced more profitable potatoes. Farmers in Abashiri, on the other hand, were obliged to remain in starch oriented production partly because of plant diseases which prevented the shift made in Tokachi. Potatoes for starch are slow growth and high yielding varieties. This case study of potato production in Hokkaido shows that high yielding varieties are not necessarily the most profitable. We should be careful to evaluate regional differences in land productivity.

View full abstract

Development of multiple ridges in the southern frank of Gurjia Himal, mid-western Nepal, was studied (Fig. 1). Geomorphologic feature, a cross section (Fig. 2) and a plane figure of the multiple ridges (Plate 1) at Loc. 1, shows bulging of a gentle crest slope down to the east and subsequent subsidence of a ridge top occurred. Widening of joints, of which strikes are concordant with trends of the multiple ridges (Fig. 3), extensively occur just below the ridges (Plate 2). Open cracks in joint systems were filled with injected clay (Plate 3). Deformation of the gentle crest slope down to the east and subsequent subsidence of the ridge were undertaken by progressive widening of joint system in bed rock of the ridge as a whole due to self-gravity, considering above mentioned geomorpho-geological features.

View full abstract