376 It. A. DALY THE OKANAGAN COMPOSITE BATHOLITH 



8. The Similkameen granite bears three roof pendants. Their distri- 

 bution suggests that the present erosion surface of this batholith west of 

 the Similkameen river is not far from coinciding with the constructional, 

 subterranean surface of the batholith. 



9. The Osoyoos and Eemme] granodiorites have been extensively meta- 

 morphosed by orogenic crushing and its attendant processes. The meta- 

 morphism was both dynamic and hydrothermal. The granodiorites have 

 been locally, though on a large scale, transformed into banded gneisses 

 and schists. These changes have been brought about through the hydrous 

 solution and migration of the original mineral substance of the grano- 

 diorites, especially the more basic minerals. The dissolved material has 

 been leached out from the granulated rock and has recrystallized in strong 

 shear zones to which the solutions have slowly traveled. The shearing 

 and metamorphism probably began at a time when the Eemmel batholith 

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



10. The intensity of this metamorphism and the development of the 

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

 mountain building at the 49th parallel was caused by much more powerful 

 Compression 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. 



