LIST OF FIGURES Number 1. Beach Ridge Sand, Rongelap Island. 2. Kabelle Sand. 3. Gogan series, 4. lLomuilal Sand, 5. Gamma-ray spectra of equal amounts of old soil from 6. Gamma-ray spectrum of a 9 to 10-inch depth incre- Kabelle Island. Kabelle Island. different depths. ment from old soil compared with the gamma spectra of sbl25 ana cs?3?. 10 13 15 7. Gamma-ray spectra of depth increments of old soil taken from the surface inch. 16 8. Gamma-ray spectra of litter and guano collected in an area of old soil. 17 9. Gamma-ray spectra of equal amounts of young soil from different depths. 19 Gamma-ray spectrum of young soil from a depth incre~ ment of 9 to 10 inches compared with the gamma spectrum of Sbi2s, 20 Radioautograph obtained by exposing no-screen X-ray film approximately one cm below the soil surface in situ. 23 10. ll. 12. Radioautographs and photographs of soil core 13. An area of young soil subject to erosion. 14. Photograph and radioautograph of old soil showing correspondence of radioactive portions to organic sections. matter. 26 27 29