300 ANNUAL REPORT SMITHSONIAN INSTITUTION, 194 7 



only explain subsidence in the early stages rather than the apparent 

 long-continued relative subsidence of many oceanic atoll groups. 



While the main mechanism of oceanic atoll formation as envisioned 

 by the writer is the slow rise of ocean level, further subsidence of the 

 atoll isostatically to compensate for loading by the limestone deposited 

 is a necessary corollary. It is emphasized that this isostatic settling 

 must be a secondary consequence and not a primary factor in atoll 

 formation since the settling will always be much less than the thick- 

 ness of the limestone deposited. More rapid reef growth on the wind- 

 ward side will ultimately result in the eccentric location of the under- 

 lying volcanic pedestal which is displaced relatively toward the lee 

 side. This also causes eccentric loading, as shown in figure 15, and 

 should result in a tilting of the original volcanic core and of old, now 

 deeply buried, atoll surfaces.^ 



BIBLIOGRAPHY 

 Betz, F., and Hess, H. H. 



1942. Geogr. Rev., vol. 32, pp. 99-116. 



BUCHEK, W. 



1940. Bull. Geol. Soc. Amer., vol. 51, pp. 489-511. 



BUDDIiS'QTON, A. F. 



1943. Amer. Mineral., vol. 28, pp. 119-140. 

 Daly, R. A. 



1940. Strength and structure of the earth. Prentice Hall, New York. 

 Dobbin, M. B., Snavelt, B. L., White, G., Beeesford, R., and Perkins, B., Jr. 



1946. Seismic-refraction survey of Bikini Atoll. Bull. Geol. Soc. Amer., 

 vol. 57, p. 1189 (abstract). 

 Griggs, D. 



1939. Amer. Journ. Sci., vol. 237, pp. 611-650. 

 HOBBS, W. H. 



1944. Proc. Amer. Philos. Soc, vol. 88, pp. 221-268. 

 Jeffbets, H. 



1929. The earth. Cambridge Univ. Press. 

 Kuenen, Ph. H. 



1937. Amer. Journ. Sci., ser. 5, vol. 43, pp. 457^68. 



1941. Amer. Journ. Sci., vol. 239, pp. 161-190. 



LONGVPXLL, C. R. 



1945. Amer. Journ. Sci., vol. 243A, pp. 417-447. 

 Murray, H. W. 



1941. Bull. Geol. Soc. Amer,, vol. 52, pp. 333-362. 

 Royal Society of London. 



190^1. The atoll of Funafuti. 428 pp. 

 Stearns, H. T. 



1946. Amer. Journ. Sci., vol. 244, pp. 245-262. 

 Vening Meinesz, F. A. 



1941. Nederl. Akad. Wetensch., Proc, vol. 45, No. 1. 



'' Since preparation of this discussion, the report on drilling of Biliini Atoll has been 

 presented before the Geological Society of America (Ottawa, December 1947) by Ladd, 

 Tracey, Lill, Wells, and Cole. Calcareous sediments were found to the bottom of the hole 

 at 2,554 feet. Miocene fossils were identified from 1,305 feet. The hole was drilled on the 

 windward side of the atoll where the thickest Cenozoic section should occur (see fig. 15 

 above). 



