2 GEORGE V, SESSIONAL PAPER No. 25a A. 1912 



CHAPTER XV. 



FORMATIONS OF THE FIVE-MILE BELT BETWEEN MIDWAY AND 



OSOYOOS LAKE (MIDWAY MOUNTAINS AND ANARCHIST 



MOUNTAIN-PLATEAU) . 



Introduction. 



A large body of the Midway volcanic formation covering the area about 

 Midway town forms a natural geological province by itself. These Tertiary 

 lavas and pyroclastics are piled upon an unconformable base of presumably 

 Paleozoic sediments, for which the name ' Anarchist series ' is proposed. The 

 older series is exposed on a large scale in the belt between the main Kettle 

 river and Osoyoos lake and outcrops at a few points within the Midway volcanic 

 area. The whole of tbis stretch, where the Boundary belt crosses the volcanic 

 area and the extensive exposure of its foundation rocks, forms a convenient 

 geographical unit, the geology of which will be described in this chapter. — (See 

 Maps, Nos. 10, 11 and 12.) 



Besides the two rock groups just mentioned a fossiliferous, Tertiary series 

 of rocks will be described under the name Kettle River formation. After 

 the sediments the igneous rocks, extrusive and intrusive, will, as usual, be 

 described in their respective order of age. Some intrusive phases of the lavas 

 will be considered before the corresponding extrusives. The largest exposed 

 intrusive body within this part of tbe belt (excepting the Osoyoos batholith, 

 which will be described in the next chapter) is named the 'Rock Creek chonolith.' 

 It is intrinsically of special importance and its petrography throws much light on 

 certain members of the Midway extrusive rocks. 



Anarchist Series. 



General Description. — From a point near the confluence of Rock creek and 

 Johnston creek westward to the Osoyoos granite batholith — a distance of about 

 twenty miles — the Boundary belt is almost entirely underlain by a highly meta- 

 morphosed, chiefly sedimentary group of rocks. These compose the Anarchist- 

 mountain plateau (Plate 35) and may be called the ' Anarchist series.' The 

 name is literally not inappropriate, for these rocks cannot as yet be reduced to 

 stratigraphic order or structural system. The series is also represented in 

 detached aTeas between Johnston creek and Midway and unquestionably under- 

 lies the Kettle River formation and the Midway lavas. It is separated from 

 those Tertiary formations by a profound unconformity. West of Osoyoos lake 

 the Anarchist series is probably represented by a yet more extensively meta- 



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