Frontispiece courtesy Anthropology Department, Southern Methodist University (SMU)

Cover photo courtesy U. S. Geological Survey (USGS)

Page
[11] USGS
[12] USGS
[14], [16], [17] Willard F. Libby
[18] University of Arizona
[21] Massachusetts Institute of Technology
[22] Graduate Research Center of the Southwest
[23] Graduate Research Center of the Southwest
[25] Robert L. Fleischer
[26] Perkin-Elmer Corporation
[30] University of Texas
[32] Graduate Research Center of the Southwest
[36] Massachusetts Institute of Technology
[40] Des Bartlett, Armand Denis Productions
[43] Anthropology Department, SMU
[44] USGS
[47] USGS
[59] Author’s photo courtesy Graduate Research Center of the Southwest

Footnotes

[1]Words appearing in SMALL CAPITAL LETTERS are defined in the Glossary beginning on [page 49].

[2]The process of natural radioactive decay is described in the Appendix beginning on [page 52].

[3]The U. S. War Department program during World War II that developed the first nuclear weapons.

[4]Drawn to scale, the whole age of man is represented by less than the width of the line.

[5]For more information on the structure of atoms, see Our Atomic World, a companion booklet in this series.

[6]From the Chart of the Nuclides, prepared by David T. Goldman, Knolls Atomic Power Laboratory, August 1964.