In order to study the geographical distribution of daily snowfall in the Tohoku region and its relation to synoptic weather conditions, the 10 district regions were first identified. All of these areas experience intense snowfall by either one of the three major types of snowfall. The first type of snowfall, defined by Types D, E and F occurs in the mountainous regions with the winter monsoons. The second type, defined by Types A, B and C occurs near Japan Sea coast. Finally the third type which is associated with cyclones is defined by Types G, H, I and J.
The study of synoptic conditions associated with snowfall types has shown distinct conditions for each of the three major types of snowfall. In the case of mountain snowfall, the wind at the 850-mb level over Akita was strong. The mechanism of the coastal snowfall was found to be different between the northern (Types A and B) and the southern (Type C) regions. In the southern regions, the wind at the 850-mb level over Akita was weaker than 10m/sec, but in the northern regions rather stronger. Hence, it can be concluded that the distribution type of snowfall in the southern region is similar to that occurred in the Hokuriku region. On the other hand, the distribution type of the coastal snowfall in the northern region appears to be unique to the Tohoku region. The third major type of snowfall which is associated with cyclones is characterized by the absence of cold air at the 850-mb level. In addition, the regionality of the snowfall occurred under the strong influence of the track of the cyclone.
As a result, each of the 10 region which was defined by the probability of the simul-taneous occurrence of intense-snowfall day, may possess distinct characteristics in addition to the common characteristics associated with one of the three major types of snowfall in the Tohoku region.

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The Isawa Upland is a composite alluvial fan of the Isawa River, a tributary of the Kitakami River, and is divided into terraces at seven levels. On the other hand along the upper reach of the river in the mountainous area terraces are scattered at four levels. These terrace surfaces, composed of very thin gravel beds overlaying the Neogene formations, are considered to have been formed by lateral erosion of the Isawa River. Since the lowest terrace surface had been formed the river has been down-cutting forming narrow flood plains. In the upper reach of the river, grano-diorite is exposed along valley walls lower than the high terrace surfaces.
In the Isawa Upland, the content ratio and a mean maximum size of grano-diorite gravel in fluvial deposits increase from the higher to the lower terraces and are extraordinarily large for the present flood plain. Such characteristics in the terrace deposits are due to progressively increasing exposure of grano-diorite on valley walls caused by down-cutting of the river and active transportation caused by narrow valley width in the upper reach. However, the cause of the extraordinarily high-content ratio of grano-diorite gravel in the present flood plain is considered to be the fact that at present the Isawa River is in a down-cutting stage and is supplying abundant grano-diorite gravel from valley floors and walls in the upper reach. The fluvial conditions in the previous stages of down-cutting the other terrace surfaces in the area were probably similar to those at present.
On the other hand, the relatively low-content ratio of grano-diorite gravel in the terrace deposits, which had been thinly laid when the river was in stages of lateral erosion, is considered to be caused by more abundant supply of debris of the other kinds of rocks from mountain slopes than that of grano-diorite gravel from valley floors and walls. The abundant debris-supply from mountain slopes was possibly caused by active solifluction, because the lowest terrace surface was formed during the cooler stage about 20, 000 years ago.
It can be inferred from the discussion and the longitudinal profile along the river course, that the terrace surfaces at four levels in the upper reach are correlated to four extensive terrace surfaces in the Isawa Upland.

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The aims of this paper are to identify inter-prefectural migration patterns, and to extract “migration fields” which are defined as joint origin-destination regions of migration (Schwind, 1975).
Data for this study were taken from the Resident Registration data published by the Bureau of Statistics, Office of the Prime Minister, Japan. The data are expressed in the form of 46×46 origin-destination migration matrix.
In the first stage of the study, principal component analyses were employed to reduce the above-mentioned migration matrix to its underlying dimensions, representing regional groups of places (prefectures) treated as destinations and origins. The results are as follows:
Seven dimensions with eigenvalue of greater than 1.0, explaining about 83 percent of the total variance of the 46×46 migration matrix, were identified in the R-mode analysis, for the period of 1960-65 (Fig. 1). Dimensions in the R-mode analysis represent regions composed of prefectures (indicated by component loadings of greater than 0.5) having similar patterns of inmigration from other prefectures. Figures 2-a_??_c show the results of these dimensions.
On the other hand, six dimensions with eigenvalue of greater than 1.0, explaining about 91 percent of the total variance of the migration matrix, were identified in the Q-mode analysis, for the period of 1960-65 (Fig. 1). Dimensions in the Q-mode analysis reveal regions composed of prefectures having similar patterns of outmigration to other prefectures. Figures 3-a_??_c show the results of these dimensions.
In the second stage, canonical analysis was employed to identify the interdependencies of the inmigration (destination) regions and outmigration (origin) regions, and then to test whether migration fields defined above can be identified within Japan, for the period of 1960-65.
The results of the canonical analysis are summarized in Table 2. All canonical correlations were found highly significant by the chi-square test. And five pairs of canonical variates were formed from the migration dimensions of seven destination regions and six origin regions. So, each pair of canonical variates represents a migration field of prefectures with similar inmigration and outmigration patterns. By the empirical interpretation of each migration field, five migration fields were extracted as Eastern Japan field, western Japan field, Yamaguchi-Kyûshû field, Chûkyô field, and Ôsaka field.
How, then, did the inter-prefectural migration patterns change, for the period of 1966-70?
So, the above-mentioned same analyses were applied to the data on inter-prefectural migration stream, for the period of 1966-70. The part of results of analyses are illustrated in Figures 4_??_6 and Table 3.
For the period of 1966-70, five migration fields were extracted as Eastern Japan field, Western Japan field, Yamaguchi-Kyûshû field, Ôsaka field, and Tokyô field.

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