194 POPULATION'S OF THE SEA 



salt distribution is not distinctly zonal, and Lotze, who interpreted 

 the data differently, connected his evaporite belts across the polar 

 regions. I have taken the liberty of supplying alternative trends 

 for these intervals, which I find not inconsistent with the idea of 

 unusually moderate climatic conditions and very wide trade wind 

 belts. 



The evaporite patterns as I interpret them, therefore, reenforce 

 the paleobiogeographical evidence favoring no post-Triassic and 

 probably no post-Carboniferous drift (Cloud, 1959b, pp. 948-949), 

 Organized information relating to the orientation of the earth in 

 still older times does not as yet warrant confidence in any solution. 

 Certainly no paleobiogeographic evidence known to me requires 

 drift of either poles or crust. In the event of stepwise polar shifts, 

 moreover, one might expect to be able to identify structurally the 

 concurrently shifting path of the equatorial bulge, which should 

 have been a site of stress, and evidence indicating drastically vari- 

 ant magnetic polar positions in post- Paleozoic times requires either 

 very abrupt displacement and return of the earth's rotational axis 

 or theoretical innovations that will permit the real or apparent 

 magnetic poles to wander independently of the rotational axis. 



The satellite program will be a geologic success if it provides 

 data for a new theory of rock magnetization. The best hope for a 

 clear solution to the ultimate problem of crustal drift, however, 

 lies in more and better paleobiogeography, especially for the 

 Paleozoic sediments and in the ocean basins. 



REFERENCES 



Adie, R. J. 1952. Representatives of the Gondwana system in Antarctica. 



Intern. Geol. Congr., 19th, Algiers 1952, Symposium stir les series de 



Gondivana, pp. 393-399. 

 Agar, D. V. 1956. The geographical distribution of brachiopods in the 



British Middle Lias. Quart. J. Geol. Soc. London, 112, Ft. 2, No. 446, 



158-187. 

 Allee, W. C, A. E. Emerson, O. Park, T. Park, and K. Schmidt. 1949. 



Principles of Animal Ecology. W. B. Saunders Co., Philadelphia, Pa. 

 Arkell, W. J. 1956. Jurassic Geology of the World. Hafner Publishing Co., 



New York, N.Y. 

 Axelrod, D. I. 1952. Variables affecting the probabilities of dispersal in 



geologic time. Bull. Am. Museum Nat. Hist., 99, 177-188. 

 — — — . 1960. The evolution of flowering plants. In Evolution after 



Darwin, Vol. 1, pp. 227-305. University of Chicago Press, Chicago, III. 



