CORRELATION BETWEEN RADON AND HEAVY 
MINERAL CONTENT OF SOILS! 
R. W. CLARK? and HOLBROOK G. BOTSET? 
Pittsburgh, Pennsylvania 
ABSTRACT 
The presence of radon in the soil cannot be used as a criterion for locating oil 
fields, since the source of the radon lies in the radioactive minerals of the soil and 
not in the petroleum at greater depths. Formation contacts could be located by a 
radon survey even though obscured by top soil and vegetation, because there is 
quite likely to be a difference in heavy mineral character and content of two different 
formations. Likewise faults may be indicated if they bring two quite different forma- 
tions into juxtaposition, but there is always danger of misinterpreting variations in 
the radon content of a soil which may be due simply to local variations in the amount 
of radioactive minerals in one and the same formation. 
INTRODUCTION 
In recent years radioactive methods of geophysical prospecting 
have attracted some attention. Most prominent among these methods 
has been that of measuring the radon content of soilstand attempting 
to deduce from these results the nature of the geological substrata. 
Radon is one of the constituents of the soil gas and is the immediate 
decay product of the metallic element radium. The radon itself is 
radioactive and its radioactivity per unit of weight is several times 
that of radium, thus enabling extremely small quantities of the gas 
to be detected. It is claimed that a fault will be evidenced by a higher 
radon concentration in the overlying soil,* and that the radon content 
of the soil above an oil bearing formation is higher than elsewhere.® 
Since there were no data available as to the success or failure of these 
radioactive methods in this country, an extensive study was made of 
the radon content of soils in regions whose geology and lithology were 
1 Manuscript received, June 23, 1932. 
2 Geologist, Gulf Companies. 
3 Physicist, Gulf Research Laboratory. 
4 “Radon Content of Soil Gas,’’ H. G. Botset and Paul Weaver, Physics, Vol. 2 
(1932), pp. 376-85. 
5 F. Miiller, ““Radioaktivitailsmessungen als geophysikalische Aufschlussmethode,”’ 
Zeits. fiir Geophysik, Vol. 3, No. 7 (1927), pp. 330-36. 
6 L. N. Bogoyavlensky, ‘‘Radiometric Exploration of Oil Deposits,’ Bull. Inst. 
Practical Geophysics (Leningrad), No. 3 (1927), pD. 113-24. 
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