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patterns, their density, uniformities, and control as 
reflected on the earth's surface. Larger scales will 
be needed for detailed examination of minor conditions 
such as erosion features, etc. 
INTERPRETATION OF SOILS 
Soil maps resulting from soil surveys conducted from 
&erial photography and field work play a very important 
part in our every day lives. From these soil surveys 
and maps various land classification and reclamation 
programs can be carried out. To a considerable extent 
goil studies made from the interpretation of aerial 
photography is a special application of the interpreta- 
tion of surface configuration and drainage patterns. 
It requires however considerable attention to details or 
micro features in the analysis of surface drainage 
patterns and landform slopes. Nevertheless aerial photo- 
graphic interpretation techniques can increase the ex- 
pedience, efficiency, economy, and dependibility of 
soil surveys. The interpretation of soll erosion from 
aerial photography as differentiated from geological 
erosion can be very useful and economical in a soil 
survey. Determination of landform slopes and their 
erosional characteristics can be fairly rapidly and 
accurately accomplished by photointerpretation. Actu- 
ally soil profiles of a parent material may be deter- 
mined from an accurate landform photo map. To a certain 
extent many miscellaneous land types such as beaches, 
dunes, alluvial soils, swamps, etc. as shown on soil 
maps can be prepared directly on aerial photography 
repidly and accurately depending on the degree of detail 
or type of information required. In many instances 
aerial photography can contribute certain types of in- 
formation to a soil survey which might be missed or 
difficult to see while conducting a field survey on the 
ground. This might include such features or soil 
boundaries which are located at the foot of a slope, 
the crest of a ridge, or change in vegetation all of 
which are easily delineated on aerial photography. Also 
such things as a change in tonal or drainage patterns 
which could indicate changes in texture or soil condi- 
tions. A correlation between landforms and class of 
soll may sometimes be established for a certain area in 
which case aerial photography could expedite a soll sur- 
vey considerably. In those cases where aerial photo- 
graphy cannot be used extensively for direct soil 
classification and mapping they can and usually do re- 
duce the amount of field work. In other cases aerial 
photography may be the most expeditious Way of delineat- 
ing agricultural land use by plotting crops and their 
growth rate. Also certain microfeatures which are re- 
lated to soil structure may be much more easily seen on 
aerial photography than on the ground. Aerial photo- 
graphy also assist in determining the origin and type 
of deposition of such transported materials as collu- 
vial, alluvial, and glaciated deposits. Many types of 
Soil maps or land classification have been prepared for 
various parts of the world in which aerial photography 
has played a very important part. Soil surveys made 
without the use of aerial photography have not only been 
time consuming but have not always been entirely satis- 
factory. Therefore whenever aerial photography is 
available the various soil mapping agencies make opti- 
mum use of them. 
The photo scales used in conducting soil surveys 
from aerial photography range roughly from 1:30,000 to 
about 1:60,000 for reconnaissance mapping. Usually 
small scale mosaics are used for plotting, while large 
scales are required for field sampling. Scales of 
from 1:12,000 to 1:20,000 are usually suitable for semi- 
detailed mapping, however as aerial photography is not 
entirely suitable for detailed soil mapping, photo 
scales of 1:10,000 or larger are not normally required. 
INTERPRETATION OF GEOLOGY 
The photointerpretation of geology covers a very 
wide range of the earths sciences, however it is 
usually separated into various specialized fields. As 
in the preceding applications considerable progress 
has been made in the last few years in the interpreta- 
tion of geology from aerial photography. Practically 
all of the material presented previously in this paper, 
especially that on surface configuration and drainage 
is applicable here. The proper interpretation of per- 
     
tinent landforms which may indicate the composition, 
stratification, and other information concerning the 
underlying material is of considerable Importance to any 
geological interpretation. Because the various landform 
patterns reflect the characteristics of their associated 
materials they indicate the type of rock or formation of 
which they are composed. Once this information has been 
determined for & particular area & large part of the in- 
terpretations has been accomplished and the remaining 
work is greatly simplified. Although the earth's surface 
is composed of & great variety of consolidated, semi- 
consolidated and unconsolidated materials, the weather- 
ing and disintigration processes for a given area are 
similar for like materials. This facilitates the de- 
lineation of similar types of geological formations by 
the interpretation of aerial photography, permitting 
many phases of geologic interpretation and mapping to be 
accomplished. This is almost a daily occurence in vari- 
ous parts of the world and includes such phases as inter- 
preting glacial action, aeolian action, fluvial action 
and their resulting pertinent landforms as well as vari- 
ous phases of petrology, structuralgeology, faults, 
joints, folding and a host of other geologic features. 
While each type of rock formation will have it's own 
peculiar criteria it might be said that in general many 
of the fine-grained rocks are characterized by a well- 
intigrated, dense, nonoriented drainage pattern and 
rough, dissected topography having sharp crests with 
steep sided slopes. Other fine-grained rocks will vary 
according to their compactness, resistance to weathering, 
etc. Criteria for sedimentary rocks differ 1n their 
characteristics from the bold, massive and frequently 
flat-topped mesa-like hills with poorly developed drain- 
age patterns of sandstone; the highly dissected to soft- 
ly rounded, moderately sloping hills and highly integrated 
drainage patterns of shale; to the striking solution 
patterns and karts topography of the limestones. 
All in all aerial photointerpretation supplies con- 
giderable help to the study of many of the earths 
sciences and can successfully be used for fairly detail- 
ed geologic mapping as well as being an effective tech- 
nique for discerning surface traces of fracture patterns 
and linear systems. The photographic scales used in the 
various fields of geological interpretation are as 
varied as its usage. No one scale or even range of 
scales is applicable for all situations, in fact, as 
often as not, the type and detail of geologic mapping 
accomplished by photointerpretation is dependent upon 
the photo scales available and the clarity of the photo- 
graphy. It is not possible in this paper to present 
the various uses and interpretation characteristics of 
photogeology, however fortunately for those so interested, 
valuable reports and papers have been published describ- 
ing the many aspects of geologic interpretation from 
aerial photography. 
SPECIFIC APPLICATIONS OF INTEREST 
Many applications of the use of aerial photography 
in surface configuration, drainage, soils, and geology 
have been received by various technical reporters. 
Several of these papers have already been published in 
the Photogrammetric Engineer. The invited paper 
"Using Airphotos to Identify Construction Sources of 
Gravel" by Prof. Olin W. Mintzer - Ohio State University 
will be published in Photogrammetria and read at the 
Ninth International Congress of Photogrammetry at the 
meeting in London, England in September 1960. In sum- 
mary the applications as used in various countries and 
reported on by respective contributors are as follows: 
United States of America: 
Prof. Ta Liang (1) and Mr. Donald Lueder (1) reported 
on the use of aerial photography for many different 
purposes such as for the location of sand, gravel, and 
quarry rock, the evaluation of foundation and abutment 
conditions at dam sites, route location and analysis 
for highways and railways as well as many other engine- 
ering applications. Rather recently Professors Laurence 
Lattman (1) and Donald Belcher (2) described the use of 
aerial photography in determining microforms and frac- 
ture traces in geological mapping. Professor Charles 
Miller (1) discusses new uses of photogrammetry for in- 
creasing engineering productivity and reducing costs on 
highway projects. Mr. William Fischer (1) in his re- 
port on the use of photogeologic techniques by the 
  
  
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