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



CHAPTER XIX. 



CORRELATION IN THE WESTERN GEOSYNCLINAL BELT. 



In " lowing x^ v^„ .Jong the International Boundary we have 

 mossed the ' grain ' of the Cordillera and, in consequence, have tended to find the 



ximum number of distinct formations in our path. On the other hand, the 

 ns ^ness of the belt which has been mapped affords a relatively small chance 

 for "iscovery of fossiliferous or other horizons which can be used for direct 



corrc-.tion of the formations with the standard systems. Correlation of the 

 rocks actually studied within the different mountain ranges is, thus", a matter 

 of no little uncertainty. In face of that difficulty it will be well briefly to review 

 the > 7 ~ ui which the writer has ventured to make the correlations so far 



stat id scarcely be stated that many of the assignments of the for- 



matii ^e eastern ranges to definite geological dates have been made in 



light of information won from the western ranges. Owing to the construc- 

 tion of the preceding part of this report many of these considerations have not 

 been expressly stated; it has seemed better, for the sake of brevity, to concen- 

 trate such arguments in the following table of correlations with its accompany- 

 ing explanation. 



Principles Used in Correlation. 



The principles on which the correlation of the formations occurring in the 

 Boundary belt, has been based, include some which are obvious and commonly 

 used; others are open to more or less debate. 



1. Fixed horizons. — These include the Cultus formation (Triassic), the 

 Chilliwack series in large part at least (Upper Carboniferous), the Pasayten 

 series (Cretaceous, Shasta-Chico), the Kettle River formation (Oligocene), 

 the limestone-quartzite series at Rossland and Little Sheep Creek valley 

 (Carboniferous). The Huntingdon formation at the western end of the section 

 is fossiliferous and probably of Eocene (Puget group) age. The younger 

 argillite of Little Sheep Creek valley south of Rossland is fossiliferous and 

 doubtless Mesozoic. 



2. Relation to the Rocky Mountain Geosynclinal. — At the summit of the 

 Selkirks the Cambrian and conformable pre-Olenellus formations plunge under- 

 ground, never to reappear farther west. At least, no rocks which, with any 

 degree of plausibility, can be lithologically correlated with the Summit series 

 have yet been seen at this latitude west of the Columbia river. The reason for 

 the failure of these formations in the west has been stated in chapter VIII. It 



25a— vol. iii— 36 



547 



