186 R. W. CLARK AND HOLBROOK G. BOTSET 
Figure 3 shows almost a parallelism between the radon content of 
the soil and its heavy mineral content. This is one of many profiles 
across the South Liberty dome, all of which are generally similar. 
Such an abundance of corroborative evidence leads one to conclude 
that the radon content of soils is directly related to and due to the 
presence of radioactive minerals in the soils. 
CONCLUSIONS 
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. For- 
mation contacts could be located by a radon survey even though ob- 
scured by top soil and vegetation, because there is very likely to be 
a difference in heavy mineral character and content of two different 
formations. Likewise faults may be indicated if they bring two dif- 
ferent formations 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 radio-active 
minerals in one and the same formation. 
516 
