500 DEPARTMENT OF TEE INTERIOR 



2 GEORGE V., A. 1912 



Petrography. — In the field the porphyry has great uniformity of colour, 

 texture and grain. It is a light-gray, fine-grained, strong rock, breaking with 

 a sonorous ring. Nowhere could evidences of crushing be discerned. The 

 phenocrysts are orthoclase, andesine, brown biotite, and green hornblende. The 

 ground-mass is a microcrystalline, granular aggregate of orthoclase, plagioclase, 

 and quartz, with accessory magnetite and apatite. The feldspars are generally 

 more or less altered. The hornblende is usually represented only by pseudo- 

 morphs of carbonate and chlorite. The biotite is much less thoroughly altered. 

 The specific gravities of the two freshest specimens collected are 2-623 and 

 2-617. 



Chemically and mineralogically, though not structurally, this porphyry 

 is in many essential respects like the younger phase of the Similkameen 

 batholith. As the younger and older phases of the batholith are of common 

 magmatic origin and nearly of contemporaneous age, and since we have grounds 

 for correlating the older phase with the Castle Peak stock, it seems simplest to 

 regard the syenite porphyry as a satellite of the Castle Peak stock and both of 

 those bodies as satellites of the Similkameen batholith. 



Correlation. — A tentative correlation of the Similkameen batholith, Castle 

 Peak stock, Lightning creek diorite bodies, and syenite porphyry chonolith may 

 be expressed in the following form : — 



Okanagan range — Hozomeen range — 



Similkameen batholith. Castle Peak stock. 

 Older phase. Principal phase. 



Basic contact-shell. Basic contact-shell. 



Younger phase. Syenite porphyry chonolith. 



Hozomeen Series. 



General Description. — The ridge culminating in the remarkable double 

 summit of Mt. Hozomeen is wholly composed of pre-Cretaceous rocks to which 

 the name ' Hozomeen series ' may, for convenience, be given. These rocks extend 

 from the major fault at Lightning creek, to the alluvium of the Skagit river. 

 Another area of what appears to be the same series is mapped in the Skagit 

 range. 



In both areas the rocks are enormously crushed, so much so that all efforts 

 to define the original succession or structures have so far failed. The difficulty 

 of discovering the relations of the series is enhanced by the fact that the eastern 

 or Hozomeen mass is cut off on both sides by faults and the western area is cut 

 off on the west by an intrusive granite batholith, on the south by a master- 

 fault and on the east probably by another great fault. The eastern area was 

 studied at the close of the season of 1905 ; the western area during the season of 

 1906. On neither occasion did the plan of the Boundary survey permit of the 

 study of areas more than three or four miles distant from the Boundary slash. 



