16 107 10° q J U r - - - ~ € D Nw ~s & y 8 2 gy 2 < sos S 6 Q oN er 8 (10 ‘ ~5 1" 0-4 Ss 88 OG 2 &°? 10° = 1 3" S 4 % oo 8 10 3_1° 8 1] 4 0.5 ! 1.0 2 L V5 MEV Fig. 7. Gamma-ray spectra of depth increments of old soil takan The origin of each spectrum has from the surface inch. been arbitrarily separated from the preceding one by @ factor of ten to facilitate inspection of the figure.