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SYMPOSIUM PHOTO INTERPRETATION, DELFT 1962 
materials are difficult to locate, soil engineering maps can be used to their 
greatest advantage. 
2. A general observation made during the initial projects was that soils and 
rocks in areas of high rainfall (low climatic N-values) exhibit less surface 
expression and are consequently more difficult to distinguish on the airphotos 
than materials in arid regions. It is therefore desirable to use larger scale 
photography in the higher rainfall areas: in the Howick project (fig. 3) solid 
dolerite and residual dolerite soils could not be annotated on photography of a 
scale smaller than 1 : 12,000, whereas detailed delineations could be made in 
the arid Mariental area (fig. 6) on a photo scale of 1 : 30,000. 
3. The need for preparing systematic inventories of available construction 
materials on many different projects in a developing country like South 
Africa, points to the necessity for sub-division of the land surface into major 
regions on a basis of lithologic and climatic criteria. Further research will be 
aimed at mapping representative areas within each such region. 
Acknowledgements 
Acknowledgment is made to the sponsors of this work, the National Institute 
for Road Research of the South African Council for Scientific and Industrial 
Research, for assisting in the preparation of this paper and for granting per 
mission for publication. The Vryburg and Mariental projects were carried out 
on behalf of Messrs. Kantey and Templer, Consulting Civil Engineers, and 
the Author is grateful for their permission to publish material from these two 
projects. The Author is indebted to Mr. A. A. B. Williams for his invaluable 
advice and assistance at all stages of this work. 
References 
1. Annual Report of the National Institute for Road Research, “Council for Scientific and 
Industrial Research”, 1959-60, and unpublished reports by H. H. Weinert. 
2. Jennings, J. E. B. and A. B. A. Brink. A guide to soil profiling for civil engineering 
purposes in South Africa. “The Civil Engineer in South Africa”, Vol. 3 No. 8, August 1961. 
Discussion 
Mr. S. Radwanski (U.K.) made the following comment: Mr. Brink has tried to bring some 
aspects of pedology to the attention of civil engineers and this is exactly what we have been 
trying to do in Pakistan. Both the pedologist and the engineer need each other and can only 
benefit through close cooperation. One example is a drainage or irrigation scheme which, among 
other things, requires basic knowledge of water behaviour in the soil. The engineer would 
look upon it from the point of view of estimating drain spacing, disposal of water and a 
number of other engineering considerations. The pedologist would investigate water table 
fluctuations, capillary rise, water uptake by plant roots and generally the behaviour of water 
in the soil profile. None of these problems can be considered separately. We should start by 
attempting to find similarities in our respective branches of science and leave the differences 
alone. 
Prof. Miles (U.S.A.) asked if a statistical sampling had been attempted of the engineering 
soil areas delineated by the methods described. The speaker answered that a statistical analysis 
had been made of an independent soil survey on the Mariental map, which proved the validity 
of grouping of soils. The results were discussed in a publication by Kantey and Williams: 
“The use of soil engineering maps for road projects”, The Civil Engineer in S. Africa, Aug. 1962.