THE CORDILLERAN MESOZOIC REVOLUTION. 



Certain features connected with the occurrence of plutonic 

 rocks on the western side of America suggest hypotheses which 

 have an important bearing upon our general conceptions of the 

 structural development of the continent. These features are but 

 imperfectly and very partially recorded thus far in geological 

 literature, owing to the vastness of the field and the meagre 

 amount of investigation which has been devoted to it. Yet 

 enough facts have been accumulated to have impressed the writer 

 that they point to generalizations which have not yet been fully 

 presented for the consideration of students of continental 

 problems. To formulate these generalizations is the object of 

 this brief note. It is not the purpose of the writer to add to the 

 record of facts so much as to connote the more important of 

 them and to suggest their cumulative significance. 



The researches of Richardson 1 and Dawson 2 on the coast and 

 islands of British Columbia have shown that the Cretaceous rocks 

 of that ^region, ranging from the Aucella bearing horizon (Neoco- 

 mian) to the Chico, repose upon a profoundly eroded complex 

 of granite and metamorphic rocks. The disturbances which have 

 affected these Cretaceous strata since their deposition have been 

 of a local rather 1;han of a regional character. They lie upon the 

 old basement usually in but little disturbed attitudes, or are 

 inclined at low angles, though occasionally they are faulted or 

 sharply folded along certain lines of post-Cretaceous movement. 

 The same condition seems to generally characterize the more ele- 

 vated early Cretaceous rock of the British Columbian interior 

 along the canon of the Fraser river. Jurassic rocks have been 

 described from British Columbia, but the Geological Survey of 

 Canada has since come to the conclusion that these rocks are' 



1 Reports of Progress, Geol. Survey of Canada, 1871-2, 1872-3, 1873-4, I 874-5, 

 1876-7. 



2 Report of Progress, Geol. Survey of Canada, 1878-9. Annual Report (New 

 Series) Vol. II., 1886. Geol. Survey of Canada, Report B. 



579 



