304 H. D. Oldham — Probable Changes of Latitude. 



the extreme cold which now prevails in that region, was never fully 

 understood till it was described and emphasized by Baron Norden- 

 skiold. In a lecture of his published in this Magazine, after review- 

 ing the evidence of the fossil flora and fauna, he remarks on the 

 favourable nature of the country for geological investigation, on the 

 completeness of the series extending one may say from the Silurian 

 to the Tertiary, and emphasizes the fact that, in all the sections he 

 had examined, he never saw a boulder "even as large as a child's 

 head " in any rock of Tertiary age or older. 1 Various hypotheses 

 have been propounded to account for these warm climates in the 

 Arctic regions without involving a shifting of the earth's polar axis ; 

 the most ingenious and captivating of these is doubtless Mr. Wallace's 

 modification of Dr. Croll's theory, according to which the mild 

 climates of the polar area were due to the warming effects of currents 

 of heated water, from the equatorial regions, which have been cut off 

 by a gradual development of the continental areas. Looked at from 

 the polar point of view, this hypothesis was legitimate and competent 

 enough to account for the facts it was intended to explain ; but an 

 hypothesis is only acceptable as long as nothing directly incompatible 

 with it is known, and however competent the hypothesis may be to 

 account for the mild climates of what are now the Arctic regions, it 

 is absolutely incompatible with the evidences of repeated glaciation 

 in low latitudes which I have referred to above. 



Mathematicians forbid us to explain the circumstances by a shift- 

 ing of the axis of revolution of the earth. Whether in this they are 

 right or wrong is immaterial, for it seems to me that there is an 

 equally satisfactory hypothesis open to us. Mr. Fisher, in his 

 " Physics of the Earth's Crust," has given good reasons for supposing 

 that there is a fluid or semifluid layer intervening between the solid 

 core and the solid crust of the earth, — in other words, that the latter 

 has a power of shifting its position on the former ; if this theory be 

 accepted, it is quite conceivable that the portion of the earth's crust 

 which now occupies the polar circle may once have lain under the 

 Equator and vice versa ; indeed I find in Mi\ Fisher's 2 book an asser- 

 tion of the probability of this shifting of the polar and equatorial 

 areas based on reasons quite different from and independent of those 

 I have given for the same conclusion. 



The known facts of stratigraphical geology, more especially the 

 existence of regions which can be proved to have undergone com- 

 pression to the extent of two or more times their present dimensions, 

 in immediate proximity to others in which the beds have suffered 

 little or no compression, show that to some extent this shifting of 

 the crust of the earth over its core must take place, and almost the 

 only argument that can be produced against an extension of the same 



1 Geol. Mag. 1875, p. 531, and 1876, p. 266. I cannot help contrasting this 

 ■with my own experience in the Himalayas, where the series is well exposed in 

 numerous deep valleys, where there is an extensive series of heds extending from even 

 hefore the Silurian to the Tertiaries, and where evidences of pre- Tertiary glacial 

 action met me, I might almost say at every turn. 



2 Physics of the Earth's Crust, p. 184. But earlier still see " On a Possible Cause 

 of Climatal Changes," by Dr. John Evans, F.E.S., E.G.S., Geol. Mag. 1866, p. 

 171.— Edit. 



