1. A summary of references pertaining to obsidian hydration dating, as of 1973, may be found in the M.A. Thesis of Jon Ericson, University of California, Los Angeles (1973).
2. This was first pointed out to us by C.W. Meighan, UCLA.
3. W.A. Weyl and E.C. Marboe, The Constitution of Glasses, Vol. II, part 1, p. 598 (Interscience, New York, 1964).
4. E.C.T. Chao, “Tektites,” in the Encyclopedia of Atmospheric Sciences and Astrogeology, R.W. Fairbridge, ed., Reinhold, New York (1967) 974.