132 



Whatever be the explanation, it is clear that the Shuswap 

 series has not been seriously affected by dynamic metamor- 

 phism. The strata and most of the injected granites 

 were completely or almost completely recrystallized while 

 the strata lay nearly flat. In some localities the effects 

 of dynamic metamorphism have been superposed on those 

 due to previous static metamorphism. An example is 

 illustrated on page 131. Similarly, thermal metamorphism 

 produced by sills or batholiths is generally easy to dis- 

 tinguish from the prevailing regional type. Contact 

 action has either coarsened the grain of the invaded 

 formation or has developed hornfelses bearing minerals 

 characteristic of plutonic contacts. The older members 

 of the Shuswap series are, in general, more coarsely crys- 

 talline than the younger, partly because of deeper burial, 

 but more because of the greater abundance of intrusions 

 at the lower horizons. 



BELTIAN SYSTEM. 



Unconformably overlying the Shuswap terrane in the 

 Selkirk mountains is a vast thickness of conformable, 

 unfossiliferous sediments, for which as a whole the name, 

 Selkirk series, has been adopted. The lower and greater 

 portion of these beds is of pre-Cambrian age ; the uppermost 

 beds, as exposed in the railway section are referred, on 

 stratigraphic evidence, to the Lower Cambrian. The 

 group is clearly the northern continuation of the Belt 

 series of Montana and Idaho. To the Pre-Cambrian 

 portion of each series Walcott has applied the name 

 ' Beltian ' as a systemic designation and it will be adopted 

 for present use. 



In the railway section the Beltian is constituted of the 

 following members. : 



