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SCIENCE 



[N. S. Vol. XL. No. 1027 



ried forward these ideas of polar wandering 

 to the present day. The hypotheses have 

 grown, each creator selecting facts and build- 

 ing up from his particular assortment a fanci- 

 ful hypothesis of polar migration unrestrained 

 even by the devious paths worked out by 

 others. 



If these varied and contradictory hypotheses 

 were kept merely as exhibits of those strange 

 creations of the mind which are stored in the 

 museum of pseudo-science, there would be 

 little present need for a discussion of the 

 subject ; but such is not the case. Able workers 

 in the fields of natural science, a number of 

 them deservedly of the first rank, overlooking 

 the fatal mathematical objections, impressed 

 by the apparent authority of the originators of 

 some of the hypotheses, and assuming that 

 these authors had made a thorough investiga- 

 tion, have, while treating the subject cau- 

 tiously, still given it serious attention. This 

 is especially true of that very elaborated 

 scheme of a pendulating earth put forth by 

 Eeibisch and voluminously supported by Sim- 

 roth. It has been brought to the attention of 

 the American scientific public in a favorable 

 review by E. E. Eichardson in Science,^ and 

 more lately by Grabau, who discusses this and 

 other hypotheses of polar migrations on pages 

 891-899 of his recent work on " The Principles 

 of Stratigraphy." In this work in fact the 

 only hypotheses of climatic change through 

 geologic time which receive detailed treatment 

 are those of polar migrations, while certain 

 important hypotheses, such as those of possible 

 changes in the deep oceanic circulation, or 

 changes in solar radiation, receive no mention. 

 Although Grabau states that the pendulation 

 theory is still too new and too little tested to 

 receive more than respectful attention, he 

 nevertheless regards it as a working hypoth- 

 esis which is likely to be of much value, and 

 from the space he devotes to it clearly con- 

 siders it of much importance. The writer's 

 high opinion of Grabau's " Principles of 

 Stratigraphy " has been expressed recently in 

 Science and it is because of his estimation of 

 the importance of that work that this article 



1 Vol. XXVIIL, pp. 375-379, 1908. 



is written. The wide degree to which the 

 " Principles of Stratigraphy " will be studied 

 in America during the next decade will spread 

 equally widely these ideas of polar migrations. 

 There is need in consequence that the lines 

 of counter arguments should be definitely set 

 forth. 



What then, briefly, are these hypotheses of 

 polar wanderings and on what kind of evi- 

 dence do they rest? 



Some seventy years ago the proofs were 

 developed of recent continental glaeiation, in 

 middle latitudes. This was in striking con- 

 trast with the floral evidence of the mid- 

 Tertiary warm temperate climate which pre- 

 vailed in Greenland and Spitzbergen. The 

 recognition of these great climatic changes in 

 late geologic times gave rise to the suggestion 

 that a migration of the poles seemed the 

 simplest means of accounting for them. Sir 

 John Lubbock in 1848 communicated a taper 

 to the Geological Society of London upon this 

 subject and Sir Henry Delabeche discussed it 

 in his presidential address in 1849. Mr. John 

 Evans in his presidential address to the same 

 Geological Society in 1876 recurred to it. 

 Evans, after describing a system of geological 

 upheaval and subsidence, evidently designed to 

 produce a maximum effect in shifting the 

 polar axis, asks: 



Would not sueh a modification of form bring the 

 axis of figure about 15° or 20° south of the present, 

 and on the meridian of Greenwich — that is to say, 

 midway between Greenland and Spitzbergen, and 

 would not, eventually, the axis of rotation corre- 

 spond in position with the axis of figure? 



It was in answer to these questions that 

 George H. Darwin wrote his conclusive paper. 



We may pass next to the far more extrava- 

 gant demands of the hypotheses framed in 

 later years and in disregard of Darwin's work. 

 The exact references are all given by Grabau. 



In 1901 Eeibisch proposed a theory of 

 polar pendulation, i. e., a back and forth migra- 

 tion of the poles along a certain well-defined 

 path. An axis of oscillation he supposed 

 to pass through Equador and Sumatra. These 

 points have consequently never changed in 

 latitude. The axis of rotation is supposed to 



