xiv DEPARTMENT OF THE INTERIOR 



2 GEORGE V, A. 1912 



CHAPTER XV. 



Page. 

 Formations of the five-mile belt between Midway and Osoyoos lake (Midway 



mountains and Anarchist mountain-plateau). 389 



Introduction 389 



Anarchist series 389 



General description 389 



Nature of the metamorphism 391 



Rock Creek plutonic bodies 392 



Diorite 392 



Granodiorite 393 



Dunite 393 



Kettle River formation 394 



General description 394 



Geological age 39T 



Midway volcanic group (in part) 398 



General description 398 



Petrography of the subalkaline lavas 398 



Rock Creek chonolith 401- 



Structural relations 401 



Dominant rock type 401 



General description. . 401 



Rhomb-feldspar 402 



Other constituents 404 



Chemical composition and classification of the rock 405 



Contact phase of the chonolith 408 



Other intrusions of rhomb-porphyry 409 



Extrusive phase of the rhomb-porphyry 410 



Analcitic rhomb-porphyry (shackanite) 411 



North of Rock creek 411 



Other occurrences 415 



Intrusive rocks cutting Kettle River strata 416 



Porphyrites 416 



Pulaskite porphyry 417 



Order of 'eruption of the Midway lavas 420 



Structural relations of the Columbia mountain system west of Christina 



lake 420 



Correlation. 422 



CHAPTER XVI. 



Formations of the Okanagan range and of Kruger Mountain plateau. . . . 425 



General description of the batholithic area 425 



Roof -pendants .*. 429 



Unity of the composite batholith 431 



Sedimentary rocks and associated basic volcanics 432 



