Another phase of research Is the evaluation of color photography. In small 
areas in California and Nevada 580 linear miles of color photography have been 
flown over sedimentary, metamorphic, and igneous terrane. This photography, 
primarily vertical, has a scale of 1:10,000 and was taken with a [2=inch focal 
length lens. It is being evaluated not only as to applicability in geologic study, 
but also more fundamentally from the standpoint of understanding color differences 
seen in the transparencies and those seen in the field. Preliminary evaluation has 
not yet been completed. 
Although research is a necessary part of any progressive scientific field, 
there is no organized photogeologic research program within the Geological Survey, 
but rather research is carried on primarily as part of and as an outgrowth of operations. 
There is no question that there is a need for continued and even greater amount of 
research in photogeology. 
Training 
Training in photogeology by personnel of the Photogeology Section has the 
two-fold objective of familiarizing geologists with the basic principles of photo- 
geologic interpretation and with the various photogrammetric instruments, such as 
stereometers and planimetric plotters, used in photogeologic study. Training is 
carried on formally in Menlo Park, Califomia, and Denver, Colorado, and in- 
formally in Washington, D. C. Specially designated training personnel are in 
charge of instruction in Menlo Park and Denver where large numbers of field geolo- 
gists are headquartered. Instruction Is offered to Survey geologists who may be 
interested. Obviously a short training period is insufficient for one to become a 
proficient interpreter or skilled technician with various instruments, but the back- 
ground is given for continued training on an informal basis, and personnel are 
available to assist all interested geologists on that basis. Approximately 125 
geologists have completed the training courses offered. The long-range objective 
of this training is, of course, to stimulate interest in and use of photogeologic- 
photogrammetric procedures in geologic mapping. 
It is gratifying to know that this training has been well received and that 
for the number of persons who have taken the courses several more have become 
aware of and developed an interest in photogeologic procedures. All three of the 
Geological Survey centers provide instruments, insofar as supply permits, to 
geologists who wish to use them in their studies. The establishment of formal training 
positions in Denver and Menlo Park some two years ago is in itself an indication of 
progress that has been made in promoting the use of photogeologic techniques in 
geologic study within the Geological Survey.