The writer has conducted detailed field surveys on landforms and structures of valley head areas in hilly lands of the Nishitanaka region, the vicinity of Sendai, in order to clarify the process of valley development.
The valleys in this area are composed of three topographic units, i. e. valley head, Vshaped valley, and V-shaped valley with flat bottom, from upstream to downstream. The valley head is classified into three types, namely, large-trough type (large shallow valley head with concave profile) (Figs. 3, 4-a, b), spoon-shaped type (Figs. 3, 4-c), and small-trough type (Fig. 3).
The built-up periods of these valley head types can be inferred from the correlations with terrace surfaces.
The terrace of Nishitanaka can be classified into three surfaces of I (hill top surface), II, and f (fill top terrace) in descending order of elevators (Fig. 1).
Large-trough type valley head is considered to have been formed between the formative periods of the terrace I and 1f, about 30, 000-60, 000 y. B. P. Under wet and cool climate toward the Wurm glacial stage, flow type landslides (Varnes, 1958) with volumes of on the order of 104 cubic meters took place on bedrocks and terrace gravels which had been weathered during the preceding interglacial stage. As a result of occurrence of flow type landslides, large-trough type valley heads were scraped out and landslide debris filled the floor of V-shaped valleys and formed gentle slopes on the terrace I surface (Fig. 6).
Spoon-shaped type valley heads have been extended toward upstreams by headward erosions through the late Wurm glacial stage (30, 000 y. B. P.) to the present. The headward erosion is resulted from slide-type failures on the order of 103 cubic meters in volume, which occurred along joints in bedrocks and pipe networks (Whipkey, 1965) in soils (Fig. 7).
Small-trough type valley head occurred on valley-side slopes head hollows of largetrough type valley head as results of non-cyclic landslides.
Development of valley heads has been generally controlled by the change of local base-level and the topographic feature of each valley head types has been characterized by climatic changes.

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Koji Iizuka (1906_??_1970) is a Japanese geographer, who introduced French school of geography to Japan, attempting to bring about a revolution in human geography in Japan. He continued to make various comparative studies on culture, being deeply conscious of his country's fluctuating situations. After World War II he played an important and leading role in the development of democratic principles in Japan.
In this paper the writer reviewed Iizuka's research activities from 1930 to 1945. The writer divided this period into six parts, and described how Iizuka did his research activities under different circumstances.
I. Just before and during his study in France (April, 1930 December, 1934)
Iizuka appreciated that P. Vidal de la Blache's “Principes de Geographie Humaine” was based on bionomical method. Being attracted by this book, he decided to study, in France, geography as social science. In France he had a new understanding of cultures of Europe and Japan. Moreover, he clearly understood the position of Japan in the world just after the Manchurian Incident.
II. Just after his return to Japan (January, 1935_??_March, 1938)
Although he was much concerned about critical conditions inside and outside our country, he devoted himself to writing the results of his study in France and published two writings “79 Degrees North” and “Problems in the History of Human Geography.”
III. During the China Incident (April, 1938_??_March, 1941)
. He felt that the war between China and Japan was essentially the Japanese invasion. So, he decided to go on with his work, trying not to be swayed by the situation. For that reason, he chose the work of translating Vidal de la Blache's “Principes de Geographie. Humaine” and L. Febvre's “La Terre et l'Evolution Humaine” into Japanese.
IV. Just before and after the outbreak of the Greater East Asia War (April, 1941-March, 1942)
He changed his attitude, and began to participate in the situation because he felt a critical moment that the United States with overwhelming economic power and Japan were confronted each other. He supported the outbreak of the war because he thought that the war was actually between Japan and the United States which was a imperialistic country, and that Japan had marked a period of exultant aggression at the beginning of the war. He thought that the Greater East Asia Co-Prosperity Sphere must be realized. Therefore, he proposed that it was necessary for Japan to be more industrialized, and for the Sphere to be reorganized, making use of the actual circumstances in this Sphere.
V. In the middle of the Greater East Asia War (Summer, 1942_??_Spring, 1943)
While he supported the formation' of the Greater East Asia Co-Prosperity Sphere, his studies were away from the main current of the time. Among his studies were criticism on geopolitics, the history of contacts between different cultures, and the progress of geographical theories and the change in world view.
VI. In the latter half of the Greater East Asia War (Summer, 1943_??_Summer, 1945)
He anticipated the defeat of Japan. It was appeared in the following points. 1) He made it clear, by studying a comparison of civilizations, that Japan had not reached modern civilization. 2) He criticized theoritical studies of geography in Japan. 3) He criticized the irrational administration systems and the feudalistic moral civilization of Japan. However, he made these remarks while supporting the formation of the Greater East Asia Co-Prosperity Sphere. He did not expect a social reform after the war.
It can be said that his way of participation in the situations is characterized as follows 1) He did not resist the internal order. Even if he sometimes criticized the administration, it was done within the limits of the order.
2) He tended to make the situations objects of study.

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Considering a long-wave radiation field as a model, it should be noted that radiative energy is basically redistributed on the ground-surface in the rural area, but in the urban area it is redistributed on the roof-level and the ground-surface. The urban roof-level is exposed to long-wave radiation additionally caused by the aerosol layer and the warm vertical temperature structure of urban atmosphere besides background long-wave radiation. The urban ground-surface is, moreover, under influence of screen effects due to buildings. This suggests that the restraint of radiative cooling resulting from the double screen effects on the urban ground-surface is one of the main causes of the urban heat island.
The objectives of this paper are to obtain the difference between long-wave radiation balance components on the roof-level and on the ground-surface in the urban area, and to discuss the screen effects (the effects of buildings) upon the long-wave radiation field on the ground-surface in the urban area. Measurements of long-wave radiation balances on the ground-surface and on the roof-level were achieved in the urban area of Tokyo on clear nights. The radiation sensors were polyethylene-shielded net radiometers (C. S. I. R. O. Net Radiometer Model CN-l and CN-2). The measurement accuracy of the sensors was ≤±4%. Upward long-wave radiation (R↑) was computed from measured surface temperatures and Stefan-Bolzmann's Law (assuming a concrete emissivity of 0.92 by Falckenberg (1928)). As observations are restricted to nights, the radiation balance equation is expressed by a simple form:
RNet=R↓+R↑(1)
where RNet is net long-wave radiation; R↓, downward long-wave radiation. Downward long-wave radiation (R↓) was computed by equation (1).
The results were as follows:
1) Net long-wave radiation (RNet) on the urban ground-surface is consistently half as much as that on the urban roof-level. This is largely because downward longwave radiation (R↓) on the urban ground-surface is greater than on the urban roof-level. 2) The increased downward long-wave radiation (R↓) on the urban ground-surface is explained by taking the screen effects due to buildings into consideration.
3) It is clear that long-wave radiation components are extremely influenced by clouds. The increase of cloudiness, in particular, causes the increase of downward long-wave radiation (R↓), and then the decrease of net long-wave radiation (RNet). On a closer examination, cloudiness is also of greater influence upon long-wave radiation components on the roof level than on the ground-surface.
From this analysis the existence of the screen effects due to buildings on the urban ground-surface can be confirmed.

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The purpose of this study is to clarify the diurnal variation of global radiation and diffuse radiation on the hill slopes of Nihon Davos in the Sugadaira Plateau, Nagano Prefecture. The locations of the five observation points are shown in Fig. 1. The observation was held from 6:20 a.m, to 4:50 p.m. on the 4th of November, 1978 and the weather condition during this period was perfect cloudless.
The result of the observation are summarized as follows:
1) The global radiation on a horizontal surface on the top of the hill is larger than those on other slopes all day (Fig. 7). The probable cause may be due to the higher ratio of sky to the hemisphere at the top than those at other points (Table 1).
2) Excepting the northern point, four points have two peaks in the diurnal variation of diffuse radiation. The first peak occurred early in the morning on the top of the hill and the eastern slope but it appeared before noon on the southern slope and western slope. On the other hand, the diffuse radiation on the northern slope has only one peak after sunrise and after that time it is very low and constant until sunset (Fig. 8).
3) As a result of the observation held on cloudless day, the diurnal variations of global radiation on the sloping surfaces are similar to the usual theoretical results of direct radiation on sloping surfaces (Fig. 9).

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