224 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1924 



obstacle, again outline on the Pacific the regular arc ending at New 

 Zealand ? To these questions of Yf egener I confess I have often been 

 tempted to respond in the affirmative. 



But Wegener goes further still, so far that one hesitates to follow 

 him. He does not hesitate to attribute to the resistance of the deep 

 fluid interior on which the continents float and in the interior of 

 which they are plunged, of attributing, I say, to this resistance, the 

 tangential movements which have folded the lithosphere and fash- 

 ioned the mountain chains. The long chain which dominates the 

 western shore of America, the Kocky Mountains and the Andes, 

 would result, according to him, in the marginal folding of the 

 border which serves as prow to the immense ship wdiile it drifts 

 toward the west. Perhaps it might be thus for any long chain; 

 it would indicate the direction and, on carefid consideration, 

 the trend of the ancient continental drift. Australia would for- 

 merly have moved toward the east before advancing toward the 

 North ; Africa would have had, at a very remote epoch, at the end of 

 the Primary, a rapid movement of drifting toward the south, to 

 which the mountain chain of the Cape bears witness. 



Such a theory has the possibility of being extremely convenient, 

 an advantage which is not without grave danger, the danger of 

 making superficial minds believe that enigmas are solved when they 

 are simply displaced and replaced by those more general and much 

 more irresolvable. Yes, it may seem very convenient to unite two 

 continents or to separate them at will; to join them to explain the 

 migration of the fauna and flora from one to the other, or the ex- 

 tension from one to another of some line of structure, for example, 

 a chain of mountains ; then separate them to explain on another oc- 

 casion the dissimilarity of biological conditions that one observes 

 there, or the difference which manifests itself in the geological 

 history of two continents during an indefinite period of time. It is 

 also very convenient to admit, with regard to the continents, that the 

 terrestrial poles could shift. This, by a stroke of the pen, does away 

 with all difficulty relating to the distribution of climate during the 

 different geological periods. And if you are adverse to the idea that 

 the axis of the earth may be movable, you will be told that this 

 mobility is not all necessary; it is sufficient, the poles remaining 

 fixed, to have the continents glide around the globe. By means of 

 this gliding you may construct at any moment the geography Avhich 

 seems to you most in accordance with the image which you have of 

 the face of the earth in keeping with the geological data at the same 

 moment of its duration. 



Here is a characteristic example of this extraordinary and very 

 seductive convenience. Toward the end of the Carboniferous period, 

 when coal was being formed in many parts of the globe by the 



