heavier. It is therefore absolutely necessary that the developing countries be 
come more and more industrialized and thus find a firm economic footing 
themselves, which will enable them to take a larger share in the huge costs 
which will be involved in their future development. 
The question is essentially whether all our aims, which are to raise the 
standards of living, can be reached in time. It appears from United Nations 
reports that nowadays a considerably higher percentage of the world popula 
tion has a diet of under 2200 calories daily than was the case in 1939. Are our 
numbers not increasing faster than we can organize our food supplies? I have 
already mentioned the aspect of the necessary investments. Another aspect 
which may become a bottleneck in an unknown number of cases is the training 
of the scientific personnel to carry out the essential research and the technical 
personnel to carry out the projects. An efficient planning on a world wide scale 
of all the available resources will be indispensable if this task is to be brought 
to a satisfactory conclusion. 
The developing countries, in raising the standards of living of their rapidly 
increasing populations, will create a great demand for raw materials and the 
need for planned development of industry and transportation. The agrarian 
economy, in particular, must also be developed to meet these ever increasing 
demands. Rapid progress of thorough scientific investigations is necessary as a 
basis for these projects: the mineral wealth, the fertility of the soils, the value 
of the forests, etc. should be known in advance. Aerial survey is one of the most 
important means of investigation of a country’s potentialities. Much data 
regarding geology, soils, vegetation, etc., can be derived from aerial photo 
graphs. The accuracy and the amount of detail obtained in this way, and the 
saving of time and money, are the reasons why nowadays almost every in 
ventory of natural recources is carried out with the aid of aerial photo inter 
pretation. The greater efficiency of the field investigations reached by this 
approach is essential to ensure a sufficiently rapid progress of development 
projects. It is not too much to say that the interpretation of aerial photographs 
has become a much more important part of aerial survey than the preparation 
of photogrammetric maps. The latter should only be considered as a pre 
requisite for the natural recources survey. 
Mineral resources development has a high priority in the economic planning 
of many countries, because most industries are dependent on minerals. This is 
especially so for heavy industry, but the power necessary for other industries, 
which may be partly based on agriculture, also comes almost exclusively from 
mineral resources. Photogeology is comparatively well developed as far as 
areas of sedimentary rocks are concerned. This is a result of the extensive use 
made of aerial photograph interpretation in oil exploration. Areas of igneous 
and metamorphic rocks have been much less intensively studied, however, 
and much remains to be done in this field. It is therefore important that at 
this Symposium, the working group on geology will concentrate especially on 
this subject. The approach of aerial photographic studies of such areas is