Ultrasonic Velocities' — Manghnani and Woollard 
295 
5. Dunites and olivine-rich inclusions in the 
Hawaiian basalts have the highest transmission 
velocities observed in this study. This material 
is most probably derived from the upper mantle. 
6. The Hawaiian rocks exhibit significant de- 
grees of anisotropy due to the differences in the 
mineral composition and orientation, and the 
geometry and orientation of the vesicles. 
ACKNOWLEDGMENTS 
The studies reported were supported in part 
by the Office of Naval Research under Contract 
ONR 3748(05), and were greatly assisted by 
the cooperation of the U S. Geological Survey 
Volcano Observatory group, and by Dr. I. L. 
Barnes and Dr. G. A. Macdonald, of the Hawaii 
Institute of Geophysics, who contributed sam- 
ples of rock for the study. We thank Drs D. L, 
Peck and H. A. Powers of the Hawaiian Vol- 
cano Observatory for their kind help and for 
providing some of the samples studied. 
REFERENCES 
Birch, F. I960. The velocity of compressional 
waves in rocks to 10 kilobars, 1. J. Geoph. 
Res. 65:1083-1102. 
— — — 1961. The velocity of compressional 
waves in rocks to 10 kilobars, 2. J. Geoph. 
Res. 66:2199-2224. 
1964. Density and composition of man- 
tle and core. J. Geoph. Res. 69:4377-4388. 
EATON, J. P. 1962. Crustal structure and vol- 
canism in Hawaii. In: Crust of the Pacific 
Basin, Am. Geoph. Union Geophysical 
Monogr. 6, pp. 13-29. 
Jamieson, J. C., and H. Hoskins. 1963. The 
measurement of shear-wave velocities in sol- 
ids using axially polarized transducers. Geo- 
physics 28:87-90. 
Raitt, R. W. 1956. Seismic-refraction studies, 
of the Pacific Ocean Basin, 1. Crustal thick- 
ness of the Central Equatorial Pacific. Bull. 
Geol. Soc. Am. 67: 1623-1640. 
Ross, C. S., M. D. Foster, and A. J. Myers. 
1954. Origin of dunites and of olivine-rich 
inclusions in basaltic rocks. Am. Min. 39: 
693-737. 
Shor, G. G., and D. D. Pollard. 1964. Mo- 
hole site selection studies north of Maui. 
J. Geoph. Res. 69: 1627-1637. 
