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MAPPING OF SURFICIAL DEPOSITS FROM AIR PHOTOGRAPHS 
Bengt Lundén 
Department of Physical Geography, 
University of Stockholm 
Box 6801, S-113 86 Stockholm, Sweden 
Surficial deposit mapping (mapping of soil types and bedrock outcrops) 
by air photograph interpretation techniques makes use of the geological 
knowledge of the interpreter and his ability to interpret the various 
elements which characterize each deposit. These elements, which are 
visible in air photographs, are termed indicators. Examples of such in- 
dicators are landform, surface texture, land-use, vegetation, topo- 
graphical position, erosional features, ditching, colour, drying charac- 
teristics and quarries. The value of these indicators has been assessed 
and the value of different photographic materials has been examined 
(Lundén 1977). 
The studies have been carried out in different parts of Sweden in order 
to test the general validity of the results. Using a good stereoscope 
the test areas were examined in different photographic materials. For 
the purpose of comparing the results surficial deposit maps of high 
accuracy were used. 
Initially when comparing the different photographic materials no map 
studies or field checks were made during the interpretation phase. In 
the final study, which showed the advantages of using air photograph 
interpretation for surficial deposit mapping, an old geological map 
was consulted and a limited field control was included. The result of 
this procedure was then compared with a modern geological map. 
The results of the study are summarized below: 
Interpretation of individual indicators followed by an evaluation based 
on the number of coincident boundaries of each characteristic (Buringh 
1960) is not a useful method for Swedish terrain. 
The value of each indicator should consider the frequency of its occur- 
rence during the mapping of the surficial deposits. 
Normally more than one indicator is applicable to an area dominated by 
a specific deposit and it is the sum of all the information that deter- 
mines the interpretation result. 
The indicators can be subdivided into two groups: (a) those of universal 
presence which enable distribution bo be determined, and (b) those of 
less frequent occurrence which only provide point information. 
From the results of the present study the most valuable indicators for 
surficial deposit mapping are landform, topographical position and vege- 
tation. 
The interpretation result improves with increased scale of the images as 
long as the film and print type remains constant. 
If a first class stereoscope is used paper prints are inferior to dia- 
positives. 
Colour film gives better results than panchromatic film when all other 
factors are equal.