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PHOTO INTERPRETATION IN EARTH SCIENCE 
probable that this method has been at least partly responsible for the discovery 
of many new oil fields. In the mining industry, the use of air photos is perhaps 
less extensive, but experimentation is in progress, and one major new discovery 
of iron ore, Cerro Bolivar in Venezuela, was made directly on the basis of 
photo interpretation (Lake, 1950). In highway engineering, photo interpretation 
has been found to make for increased economy and efficiency of operation in 
many ways. In other fields of engineering, less specific information is available, 
but it can be said that photo interpretation is assuming a role of increasing 
importance. This is particularly true of arctic regions, where the peculiar 
problems imposed by the occurrence of “permafrost,” or perennially frozen 
ground, require very specialized methods of procedure, and very careful selec- 
tion of sites for engineering operations. 
Another benefit which arises from photo interpretation, aside from expediting 
routine mapping and various practical applications, is the discovery of research 
problems. Unusual or anomalous features found on photos sometimes raise 
questions which cannot be answered from current knowledge, and thus lead to 
investigations which enlarge our understanding of earth phenomena. 
In view of the importance of photo interpretation, it is pertinent to consider 
briefly the existing training facilities in this field. At the present time, these 
facilities are by no means adequate. Elementary courses in the use of photos 
are given in some of the more progressive colleges and universities, but it is 
probable that only a minority of the geologists and engineers now graduating 
receive such training. Many oil companies and other organizations find it neces- 
sary to provide their own training for new employees. A viewpoint frequently 
expressed is that well-rounded training in the fundamentals of a professional 
field is more important than specialized training in photo interpretation proper, 
and it probably is true that the best field geologist or engineer will make the 
best photo interpreter. As in many other fields, experience is, within certain 
limitations, the best teacher, and the more advanced phases of photo interpre- 
tation are best learned by practice, with opportunity to check results. A proper 
formal introduction to elementary photogrammetry and to interpretation, 
however, does make it possible to profit more rapidly and more fully from 
experience, and to be alert to opportunities for acquiring beneficial types of 
experience. Expansion in training facilities is overdue. 
From the over-all viewpoint, present trends are toward more extensive and 
intensive application of photo interpretation in the various fields of earth 
science, toward better evaluation of its capabilities and limitations, and toward 
results of greater reliability. In certain quarters, there is perhaps a tendency 
to expect too much from photo interpretation, to regard it as a panacea for all 
manner of problems. Although this can be expected to lead only to disap- 
pointments and temporary setbacks, fortunately it is not a widespread attitude, 
and it may, indeed, be regarded as a part of the usual growth cycle of a new 
field, leading ultimately to a better appraisal of its proper functions. 
In order to utilize photo interpretation with maximum effectiveness, and 
provide an adequate foundation for it, much remains to be done. Further re- 
search and experimentation is greatly needed in many phases of the subject. 
The compilation of reference works or manuals showing the typical surface 
expression on photos of a wide range of natural phenomena, well known from 
the ground view, would be most helpful. And there is a pressing need for more 
and better dissemination of information on photo interpretation at all levels. 
Potential users need to learn of the advantages which it offers, and interpreters 
have much to learn by pooling their experiences and studying one another’s