LIST OF FIGURES Number Page l. Beach Ridge Sand, Rongelap Island. 2. Kabelle Sand. 3. Gogan series, Kabelle Island. 4. Lomuilal Sand, Kabelle Island. 10 5. Gamma-ray spectra of equal amounts of old soil from different depths. 13 6. Gamma-ray spectrum of a 9 to 10-inch depth increment from old soil compared with the gamma spectra of Sb!25 ana cst37, 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 increment of 9 to 10 inches compared with the gamma spectrum of Sbi2 20 10. 11. Radioautograph obtained by exposing no-screen X-ray film approximately one cm below the soil surface in situ. 23 12. Radioautographs and photographs of soil core sections. 26 13. An area of young soil subject to erosion. 27 14. Photograph and radioautograph of old soil showing correspondence of radioactive portions to organic matter. 29