16 1O° T T —T 10% 4 2 oo, & sg 1O7F - ~ & 3 MN o % 1" a & 8 On 4 2 os cg a ox QG °& g S 2 10° F 7 1.3 8& & " 4 8 See 1O F — 31 8 ] | 0.5 ] 1.0 2 L 1.5 MEV Fig. 7. Gamma-ray spectra of depth increments of old soil taken from the surface inch. The origin of each sapectrum has been arbitrarily separated from the preceding one by a factor of ten to facilitate inspection of the figure.

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