This is the report of the Passing Distance which was researched by analizing photographs, taken once every two seconds by a helicopter at a same speed of 40 kilometers an hour with the test vehicle (truck, cargo, 21-ton, Isuzu), of public vehicles outrunningthe above test truck.

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We have decided to draw a contour map of the waves on the other from National Disaster Prevention Scientific and Technical Center. We photographed the waves in following two ways from planes simultaneously, with the cameras equipped with synchronous shutter mechanism.
1. Successive stereophotographs are taken, so that the sea shore and oil towers in the sea can be imaged in a stereomodel and some reference points can be furnished for the facilities of the absolute orientations and the plotting works.
2. Under a basis of stereoscopic Observation, successive stereophotographs are taken so that a datum plane of 0^m can be found by the numerical method and then the wave map can be plotted.

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Aerial Photographs are used for the study of landslide provinces in northern part of Kochi Prefecture, which is one of typical areas of older rocks in Japan.
The writer obtained a distribution map of landslides by photo-interpreatation, or by detecting minor patterns of reliet drainage, vegetation land use etc, on the photographs and these interpretations are checked in the field. Distributing patterns obtained from the map are compared with geological data.
As a result, the writer found the following:
(1) About 41% of landslides are found in the Mikabu greenrocks terrain in the Sambagawa metamorphic belt.
(2) Landslides of the Chichibu belt which is mainly composed of Paleozoic non-metamorphic rocks are smaller in size and scale than those of the Sambagawa belt.
(3) A great numbers of small-scale landslides are considered as creeping of surface materials which consists of weathering products and debris on steep slopes along the V-shaped valley.

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The term soft ground is used to describe areas which are composed mainly of unconsolidated muddy deposits and organic materials, and are found in recent alluvial lowlands. Such areas are causing much trouble during the construction of buildings and civil engineering structures. Ground subsidence due to the taking up ground water, and damage to structures are frequent in such areas.
The basic concepts and techniques used to interpret engineering soils bythesy stematic and morphometric analysis of micro-geomorphology of recent alluvial lowlands using aerial photographs, and their applicability to engineering soil surveys, above all in soft ground conditions, are discussed in this paper.
(I) Basic concepts, problems and techniques of interpretation
1) The methods and techniques of micro-geomorphological analysis are a most important part of interpretation proces singeological, soil and other land surveys by aerial photographs. But we are not satisfied to know the types of landforms alone. In order to interpretsurface materials or soils, geology, it is necessary to establish the system that we can infer these land conditions from the analysis of micro-geomorphology.
In the regions which have boen intensively utilized such as alluvial lowlands of Japan, it is better to interpret surface materials or soils by the analysis of micro-geomorphol ogical features than by the analysis of photographic tone and density. The latter should be analyzed in connexion with micro-geomorphological features of lowlands.
2) The first step to interpre tengineering soils is delimitation of the “micro-landform units” which should be closely related with the physical properties of the soil parent materials. In order to delimitate the “micro-landform units”, the principles and techniques of“ landform type” analysis on aerial photographs which have been developed and systematized by Nakano (1955, 1962^a) and his collaborators (1964) can be applied. These unies are better suited for mapping the surface distribution ranges of soft ground.
The“micro-landform units” which are classified on photographs, and are thought to be the basic terrain units to infer engineering soils, their photographic chracteristics and their relationship to surface materials or parent material of soils are arranged in Table 1-2.
The second step is to group these units into the “landform areas” depending upon the distribution pattern of these units, the geomorphological agents, their topographic locations and other criteria. “Landform areas”grouped by these criteria are one of the terrain units used to examine the geomorphological development or the sedimentary environment over the area during recent years. Considering these factors, the types of soft ground and their occurrence in a“ landform area” can be roughly interpreted using aerial photographs.
“Landformm areas” which can be expected in alluvial lowlands of Japan, main “microlandform units” which are distributed in each“landform area”, and relationship to the occurrence of soft ground are shown in Table 1-3. Fig. 1-1is a chart showing the procedure for engineering soil surveys and soft ground investigations during the preliminary or reconnaissance stage. Detailed relationship between landforms and the distribution of soft ground is tabulated in Table 1-4. (to be continued next number)

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The author who had been in Saudi Arabia as a member of the technical mission from Geological Survey of Japan September 1963 to March 1965. had been engaged in topographic survey for mineral resources prosppecting in the country.
The aerial photographs are essential means not only for topographic survey but also for geological interpretations, particularly in the non-mapped country.

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