Ce rapport essaie d'élucider les étapes d'urbanisation correspondant a celles de l'industrialisation en se basant sur l'étude du district de Mishima-Numazu.
Première époque (jusqu' à la Première Guerre mondiale)
Le degré de développement industriel était has et l'activité industrielle exercait une influence insignifiante sur l'urbanisation aux deux points de vue de l'utilisation du terrain et de la composition de la population. L'urbanisation se développait sous l'influence de tous les autres facteurs, mail sa progression était lente.
Deuxième époque (de la Première Guerre mondiale à la Seconde Guerre mondiale)
A cette époque, ce sont les capitaux d'autres régions qui font progresser la production industrielle exerce son influence sur l'urbanisation, cette phase différe de l'époque précédente. Les logements construits par les entreprises pour leers employés et les cités ouvrières constituent l'élément d'urbanisation le plus fort au point de vue de l'utilisation du terrain. Mais l'urbanisation de la main d'oeuvre agricole Bans cette région ne progresse pas beaucoup.
Troisième époque (depuis la Seconde Guerre mondiale)
Les usines, sur une plus grande échelle que précédemment, s'installent dans cette région. L'industrie se diversifie, la puissance de production industrielle, et la production, augmentent. En conséquence, l'industrie exerce une grande influence sur l'urbanisation. Ce n'est qu'à cette époque que l'urbanisation se développe aux deux points de vue de l'utilisation du terrain et de la main d'oeuvre.
Cette influence était devenue très puissance, la production industrielle influe sur l'agriculture et le commerce. L'urbanisation due à l'industriallisation à cette époque eat donc très différente par rapport aux époques précédentes.

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In such a mountainous country as Japan, alluvial lowlands are basically important for human activities, and are most densely populated. As the occupance of the earth's surface by man-made structures is essential for human activities, ground conditions of lowland areas should be considered the significant natural environment. Ground conditions are also closely related with human activities as causative factors which result in natural disasters such as ground subsidenc and earthquake damage. Almost all problems due to ground conditions which affect land use, land development and disaster prevention have resulted in the areas with soft ground conditions, as evidenced in such industrial cities situated on coastal deltaic lowlands as Tokyo, Osaka, Nagoya and Niigata, and in many other poorly-drained lowlying lowlands throughout Japan where rapid regional development is now in progress.
Ground conditions have mainly been studied by soil engineers and engineering seismologists to the present in Japan. Considering the significance of ground conditions as environment, their formations, areal differences and influences to human activities must be the subjects of physical geographical study. Numerous studies on photo analysis and interpretation in geology and soils have been conducted by many specialists, but no systematic study on ground conditions has been made in Japan or in other countries. The first purpose of this paper is the presentation of the methods and techniques used to analyze ground conditions, above all soft ground conditions by aerial photographs. The second purpose is the contribution of the methods and techniques to engineering soil survey and regional planning from the viewpoint of disaster prevention. The main tool of aerial photo analysis and interpretation used in this study is a systematic analysis of micro-landforms supported by the know-ledge of geomorphological development.
Geology and soils comprising ground conditions cannot be seen directly on aerial photographs. The main keys for interpreting geology and soils are micro-features of the earth's surface and tonal characteristics. But, the analysis of tonality is handicapped in alluvial lowlands of Japan because of intensive land utilization, and the systematic analysis of micro-landforms plays the most important role. Micro-landforms seen on lowlands can be regarded as a record of a recent episode of geomorphological development and the surface expression of sedimentary materials deposited by various agents. In other words, it may be said that micro-landforms of lowlands are the most significant indicator showing the distribution of geologic materials. Hence, the delineation of the terrain units composed of a single kind of geologic materials depending on the similarlity and homogeneity of micro-features, and the correlation of those units with engineering soils are the essential processes for determining ground conditions from the air.
The first step to infer ground conditions is the delineation of “micro-landform units”, which are the smallest land units and are composed of similar geologic materials having similar physical properties. The standard micro-landform units which are used to interpret engineering soils in alluvial lowlands of Japan are presented in Table 1. Classification of micro-landform units is based on genetic classification of landforms. These units are suited for delineating the areal extent of soft ground areas. However, geologic materials or soils inferred directly from such units are generally limited to those forming near the surface of the ground.

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The Aberdare Range, which lies north of Nairobi, the capital of Kenya, is composed of Tertiary (Neogene) volcanic rocks, such as basalt, phonolite, trachyte. Its westward slopes are steep, belonging to the main fault scarps of Eastern (Gregory) Rift Valley; while its eastward slopes are very gentle and dessected by many consequent valleys. On the interfluve ridges of a part of these eastward slopes, many native Kikuyu villages or hamlets are densely distributed. As shown in Fig. 1, villages are crowded on its eastern part at an altitude between 1, 300 and 2, 300 meters, and on its southeastern part between 1, 700 and 2, 200 meters, extraordinarily in contrast with surrounding areas. Villagers' lives chiefly depend on cultivation of subsistence crops, such as maize, pulses, potato and banana, and also on breeding of livestock such as cattle, sheep, goats and poultry (Fig. 2). The vegetation and landuse of treated area are represented by profiles in Fig. 3.
The concentration of native population mentioned above is partly or chiefly the result of former colonial policy being kept by Britain, for instance, setting up of so-called ‘White Highlands’. On one hand, it is also important to consider the natural conditions which permit such a concentration. The subject of this article is just on this point. As easily noticed, climatic factors are concerned, of which precipitation must be the most effective one in such a tropical semi-arid region. Fig. 4 shows the monthly rainfall of selected stations: Karamaini in the southern part, Fort Hall in the middle part, and Nyeri in the northern part. Mean values show two maxima and two minima in a year round, though the absolute values tell irregularity or unreliability, which is also the case of annual value as shown in Fig. 5.
Isohyets of mean annual rainfall are drawn in Fig. 6, using 110 stations which have data of over 20 years and supplementarily 63 stations which have data of under 10 years. The pattern of isohyets well indicates orographical precipitation on the eastward slopes facing the prevailing easterlies, and also tells that its northeastern part is the rain-shadow of Mount Kenya. The lower limit of location of native villages on the eastern and southeastern slopes coincides 1, 000 milimeters isohyet fairly well. Fig. 6 also contains isoplethes of annual rainfall reliability over 800 milimeters during 8 years, 1955 to 62, using the available 77 stations. And, the lower limit mentioned above seems to situate between 8/8 and 6/8.
In the next place, the upper limit must be considered. It is generally set up politically, for example to reserve forests, but it may not be the case without considering natural environments. Here, temperature is to be regarded. There are few data available in the treated area. So, to see the relation between altitude and average annual temperature, Fig. 7 was made, which implies linear relation between them. The solid line in the figure tells the lapse-rate of about 0.62°C per 100 meters. The upper limit of native villages, that is about 2, 300 meters in altitude, is to have average annual temperature of 15°C, which seems to be near the critical point or boundary for Kikuyu's traditional way of life. Moreover, the author actually saw in 1964 and 1965 that clouds often covered the summit part of Aberdare Range even in so-called long dry season. So the deficiency of sunshine also seems to relate with the upper limit here.
Now, the scarcity of native villages on the northeastern slopes can be explained by discrepancy between rainfall factor and altitudinal or temperature factor there, And, this is also the case of the Kinangop Plateau which situates below the steep west-facing scarps of Aberdare Range, and where pyroclastic porous soil and scarcity of water flow emphasize unfavorable conditions for traditional cultivation.

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Tone-density is one of the most important elements in airphoto interpretation on geology, soils and vegetation. It depends on such various factors as flight conditions, reflextion ratio of the surface controled by color, moisture content, etc., and processing conditions, so it has been apt to be treated relatively or qualitatively. The author tried to clarify the role of tone-density in interpreting soil properties quantitatively by using photo-densitometers both of convenient type and automatic type. Through the case study in peat bog regions he pointed out that the interpretation of soil conditions can be done with high accuracy by an analysis of tone-density alone, if the quality of photographs is adequate.

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