478 DEPARTMENT OF TEE INTERIOR 



2 GEORGE V., A. 1912 



and has recrystallized in strong shear zones to which the solutions have slowly 

 travelled. The shearing and metamorphism probably began at a time when the 

 Bemmel batholith was buried beneath at least 30,000 feet of Cretaceous strata. 



10. The intensity of this metamorphisin and the development of the great 

 Tertiary batholiths agree with other facts to show that post-Jurassic mountain 

 building at the Forty-ninth Parallel was caused by much more powerful com- 

 pression than that which is shown in the broader Cordilleran zone passing 

 through California; there the Jurassic batholiths are relatively uncrushed and 

 Tertiary batholiths seem to be lacking. 



11. The problems of the Okanagan composite batholith illustrate once 

 again, and on a large scale, the utmost dependence of a sound petrology upon 

 structural geology. A suggested chief problem involves the relation of mountain- 

 building to the repeated development of large bodies of superheated magma 

 only a few miles beneath the surface of the mountain range. The fact of this 

 association is apparent; its explanation is not here attempted. (See Chapters 

 XXIV to XXVIII). 



