466 DEPARTMENT OF THE INTERIOR 



2 GEORGE V., A. 1912 



GEOLOGICAL RELATIONS AND GENERAL STRUCTURE. 



The Okanagan mountains are among the most accessible in the whole trans- 

 Cordilleran section along the Forty-ninth Parallel. Even without a trail* 

 horses can be taken to almost any point in the 5-mile belt. Owing partly to 

 mere altitude, partly to the general climatic conditions, the summits are often 

 well above the timber line, while the mountain flanks are clad with the woods of 

 beautiful park lands. (Plates 40 and 41). Another special advantage in deter- 

 mining geological relations consists in the freshness of the rocks, which have 

 been heavily glaciated and have not been seriously injured by secular decay. 

 With a little searching, excellent and often remarkably perfect exposures of 

 every formation and of its more important contacts can usually be discovered. 

 Each of the principal field relations now to be noted has been determined not 

 from one contact alone, but through the accordant testimony of several favour- 

 able localities. 



The oldest rocks within the batholithic area are the quartzites and schists of 

 Kruger mountain, with their associated basic intrusives; and the roof pendants 

 of the Similkameen batholith (Figures 27, 28 and 29). Without doubt, these rocks 

 are of the same age as the similar types found in the Anarchist series. All of 

 these Paleozoic (probably in large part Carboniferous) formations had been 

 crushed and dynamically metamorphosed before the intrusion of the oldest 

 granitic component of the composite batholith (the Kemmel or Osoyoos grano- 

 diorite). 



Analogies drawn from better known parts of the Cordillera suggest that the 

 basic intrusives of Chopaka mountain are of late Paleozoic (Carboniferous) age, 

 though, of course, younger than the schists and quartzites which they cut. 



Since the rocks of the Basic Complex are crushed and metamorphosed in 

 as extraordinary degree as any of the above-mentioned formations, the complex 

 is regarded as a Paleozoic parallel to the Chopaka basic intrusives, though 

 perhaps not strictly contemporaneous with the latter. For a reason already 

 noted, the Ashnola gabbro is possibly to be correlated in age with the larger part 

 of the Basic Complex. 



The mode of intrusion and therewith the structural relation of each of these 

 basic masses to its original country rock cannot be declared. In the case of two 

 of them — the Basic Complex and the Ashnola gabbro — not a fragment of the 

 invaded formation has been found. It is, however, improbable that any of these 

 bodies ever had batholithic dimensions. Their present isolated positions and 

 the analogy of other similar gabbro-peridotite bodies in the Cordillera suggest 

 that each of them was of relatively small size. The Chopaka body cross-cuts 

 the bedding of the quartzites and schists. It may be in chonolithic relation to 

 these — that is, it may be an irregularly shaped mass magmatically injected into 

 the bedded rocks, but not, as with a true laccolith, following bedding planes. 

 The contacts are insufficiently shown to warrant any decision in the case. The 

 Ashnola gabbro may similarly be the residual part of an injected body. That 

 it was a comparatively small body is suggested by an apparent flow structure 



