1. Gast, P. W., J. Geophys. Res., 65, 1287 (1960).
2. Hurley, P. M., et al., NYO-3943, Tenth Ann. Prog. Rep. for 1962 (Mass. Inst. Tech.).
3. Hurley, P. M., et al., NYO-10,517, Eleventh Ann. Prog. Rep. for 1963 (Mass. Inst. Tech.).
4. Faure, G., and Hurley, P. M., J. Petrology, 4, 31 (1963).
5. Hamilton, E. I., Nature, 201, 599 (1964).