CONTINENTAL DISPLACEMENT — SCHUCHERT 279 



impermanence of the continents and oceans, and others who do not 

 hesitate to push the earth's poles anywhere in order to explain single 

 floral or faiinal peculiarities. 



Long before this, it has become evident to the reader that the 

 writer is iconoclastic toward the Wegener hypothesis as a whole. On 

 the other hand, he is wholly open minded toward the idea that the 

 continents may have moved slowly, very slowly indeed, laterally, 

 and differently at different times. Every student of tectonics, in his 

 reading during the past 15 years in regard to the generaliza- 

 tions attained through a study of mountain structures and their 

 meaning, must have said to himself again and again that there has 

 been actual differential continental displacement. These generaliza- 

 tions, when based upon the individual and smaller mountain ranges, 

 are not impressive, but when one begins to consider the Cordilleras 

 of the United States, with their present w^dth of more than 1,000 

 miles, the question looms large as to how much western California 

 has moved to the east. No one has yet figured this out. Further- 

 more, when one turns to the Alps and is told by the best of authori- 

 ties that their present width of some 150 miles was originally 500 and 

 perhaps 625,^^ which means that their southern limit has moved from 

 350 to 475 miles to the north, he begins to remember the statement 

 of Galileo in regard to the earth : "And yet it does move." Even 

 more impressive are the statements of Termier regarding the moun- 

 tains of central Asia, which have a combined present width of 1,845 

 miles from north to south, but which originally had an estimated 

 width of 3,G00 miles. In other words, the foreshortening may have 

 been of the order of 1,800 miles. Accordingly, we are obliged to con- 

 clude that the continents do actually move extensively, but so 

 slowly that it has taken Asia manj^ hundred million years to accom- 

 plish the previously mentioned movement. But do these movements 

 mean that the whole, or even parts, of the graniticsial have moved 

 horizontally as extensively through the basaltic sima as postulated 

 by Wegener? The writer is not the one to answ^er this question, but 

 he feels that we nmst be open minded toward at least some unknown 

 amount of continental displacements. Nevertheless, like Termier. he 

 is " struck less by the mobilit}^ than by the permanence " of the 

 earth's greater features. 



IN RETROSPECT 



Daly's new book, Our Mobile Earth, sounds the keynote for the 

 attempt to save the germ of truth in the displacement theory and 

 reconcile it with the facts that geology already has at hand. Fol- 

 lowing his lead, the writer has set down below the sequence of earth 



*iThe compression of the Alps is estimatod by Staub (Der Bau der Alpen, 1924, pp. 

 7-8) as amounting to between 690 and 1,035 miles, while Heim will only say that it is 

 well over 185 miles. 



