W. B. Taylor — Crumpling of the Earth's Crust. 261 



Eeturning to the consideration of the varying oblateness of 

 the terrestrial ellipsoid, and its geological consequences, we 

 naturally inquire what indications remain to corroborate or to 

 impair our hypothesis. Could we ascertain the approximate 

 amount of lateral excess of shell by its corrugations, say for 

 each parallel zone of ten degrees, these enlarged circumferences 

 divided by the cosine of the latitude would give us the varia- 

 tions (if any) of envelope, throughout a given meridian. This 

 is of course entirely beyond our reach. We may, however, 

 infer that the altitudes of mountain ranges should bear some 

 rude proportion to the general amount of crumpling in neigh- 

 boring districts ; and that at least some approximate indication 

 might thus be afforded or suggested. We might expect that 

 circumpolar regions should be free from mountains or plica- 

 tions; and that the inter-tropical region should contain the 

 highest elevations. 



Dr. Arnold Guyot, in his excellent summary of the Physics 

 of the Globe, prepared for Johnson's Cyclopaedia, gives the 

 following characteristic sketch : " In the New World therefore 

 the highest lands are piled up in the southwest, in the Old 

 World in the southeast. . . . On the whole, the reliefs begin 

 with the vast low plains around the polar circle, and go on 

 increasing from the shores of the Arctic Ocean toward the 

 tropical regions. The highest elevations however are not 

 found at the equator, but north of the Tropic of Cancer in the 

 Old World, in the Himalayas 28° N., and north of the Tropic 

 of Capricorn in the New World, in the Andes of Bolivia 

 16° S."* 



The same eminent and conscientious physiographer, in his 

 paper on the Ocean, remarks : " On the whole, the ocean beds 

 become less deep toward the north pole, just as the lands be- 

 come lower toward the same region. "f 



In this significant epitome — presented certainly with no view 

 of supporting an hypothesis, we have perhaps as striking a 

 suggestion of greater oblateness in former times as we could 

 expect to find preserved to us. The curious circumstance that 

 the highest lands on either hemisphere are found much nearer 

 to the Tropics than to the Equator, it must be admitted, is diffi- 

 cult of explanation. Theoretically we should expect no sensi- 

 ble differences throughout the inter- tropic zone. We may 

 however remember that the tides of the comparatively thin 

 and yielding crust exert their greatest influence on the tropical 

 zones ; being for the larger portion of the year very near to 



ceded " that a perfectly fluid spheroid has a precession scarcely differing from 

 that of a perfectly rigid one." — Mr. Darwin, in Phil. Trans. Roy. Soc, Dec. 19, 

 1878, vol. clxz, p. 525. 



* Johnson's Cyclopaedia, 1875: art. "Earth," vol. i, p. 1455. 



fSame work, 1877, art. " Ocean," vol. iii, p. 918. 



