EDITORIAL 159 



planetesimal hypothesis may have a range httle short of that of 

 the continents. The existence of various gneisses and schists is not, 

 therefore, in itself discriminative. 



It is not improbable that, in time, the notable chain of islands 

 that nov^ skirt the eastern border of the Asiatic continent from 

 Sumatra to Kamtchatka, standing along the outer border of the true 

 continental platform, will be degraded and a portion of their mate- 

 rial carried toward the mainland and re-deposited, and that this, 

 conjoined with continental detritus, will at length fill up the inter- 

 vening seas with stratified rocks, and thus extend the mainland 

 eastward to the vicinity of these islands. In the meantime, sea 

 encroachment, downward flexure, and the other agencies that affect 

 the borders of continents' may have brought about the submersion 

 of the sites of the islands themselves, in which event the border 

 formations of the continent will present the same evidences of ocean- 

 ward derivation of material that some of the coast formations of 

 the continents do today. It is obvious, however, that, in this case, 

 the phenomena will not imply a lost continent or any radical change 

 in the configuration of the lithosphere, or even of the continent; 

 much less will it afford evidence adverse to the essential permanence 

 of the continents. 



The intent of these suggestions is not to enforce any particular 

 interpretation of the extremely valuable and suggestive data afforded 

 by the oceanic islands, nor indeed to imply the limitation of alterna- 

 tive hypotheses to those here mentioned, but rather to emphasize 

 the fact that the hypotheses employed in these inquiries, as in most 

 others of a far-reaching nature, need to be traced back scrupulously 

 to their sources, and to be put into comparison with other hypotheses, 

 so that the true values and the limitations of the criteria employed 

 may be made apparent, and their dependence upon fundamental 

 hypotheses may be brought forth into sharp definiton and working 

 application. 



T. C. C. 



The article in this number of the Journal on the Tertiary glacia- 

 tion of Iceland possesses much interest for students of glacial geology 



I Op. ciL, Vol. Ill, pp. 518-30. 



