65 



the older formations from Shuswap to the Rossland group. 

 The main mass centres in the vicinity of Nelson while 

 in the outlying areas the batholith is represented by 

 smaller masses and cupola stocks. The contact phenomena 

 are very pronounced for varying widths along the border 

 of intruded rocks, while in the granodiorite the field 

 evidence at many points is excellent in illustration of 

 overhead stoping, differentiation, and absorption of roof 

 and wall rock. The rocks composing it vary from light 

 grey granite to dark grey quartz diorite and even more 

 basic types. A typical and widespread differentiate 

 is a granite porphyry consisting of stout phenocrysts of 

 feldspar i to 2 inches (2-5 to 5 cm.) in length in a rather 

 coarse grained base. 



An analysis of a specimen from Kokanee mountain 

 by Dr. F. Dittrich of Heidelberg showed the following 

 composition : — 



SiOs 66-46, Ti02 0-27, AI2O3 15-34, FesOg i-68, 

 FeO 1-83, CaO 3-43, MgO i-ii, NasO 4-86, K.O 4-58, 

 H2O 0-29, P2O5 o-o8 — Total 99.93- 



The Valhalla granite is closely associated with the 

 rocks composing the Nelson batholith and occurs as 

 large and small intrusive masses within the area underlain 

 by the Nelson batholith. It is probably early Tertiary 

 in age. The rock is a quartzose medium grained light- 

 coloured hornblende or biotite granite with local grano- 

 diorite facies. 



TERTIARY. 



Rossland alkali granitic rocks — In this group are 

 included several varieties of intrusive rocks ranging in 

 composition from alkali granite to essexite, the most 

 common type being pulaskite. These intrusives range in 

 importance from dykes and sills to bodies of batholithic 

 proportions, the latter type being well developed along 

 Lower Arrow lake south of Edgewood (see p. 94). 



OLIGOCENE. 



Kettle River formation — The Kettle River formation 

 was laid down during the Oligocene period probably 

 in a broad syncline prepared in early Tertiary. The 

 formation is now represented west of Christina lake by 



36425—5 



