166 G. M. DAWSON— STRUCTURE OF THE SELKIRK RANGE. 



under the most favorable circumstances, long and careful research. In addi- 

 tion to the difficulties of structure to be expected in any great mountain 

 system, special difficulties are found in the degree to which regional raetamor- 

 phism has been carried, in the occurrence of great volumes of contempora- 

 neous volcanic material at various stages, and (partly no doubt as a conse- 

 quence of the last) in the extreme paucity of fossil remains. Still further, 

 the circumstance that the region as a whole must be described as more or 

 less densely wooded, contrasts it very unfavorably, from a geologist's point of 

 view, with the southern and o^pen parts of the Cordillera, where he who runs 

 may read many of the main structural facts. 



Up to the present time the horizons which have in British Columbia been 

 actually fixed by paleontological evidence may be summarized as follows: 



1. Tertiary (probably Miocene). 



2. Cretaceous (various stages, probably extending from the Laramie as 

 far down as the Neocomian). ^ 



3. Alpine Trias. 



4. Carboniferous. 



5. Silurian (Haly sites beds). 



6. Cambro-Silurian (Trenton-Utica and perhaps somewhat lower). 



7. Middle Cambrian. 



8. Lower Cambrian (Olenellus beds). 



Of these horizons, all but the Miocene have been recognized in the Rocky 

 Mountains proper, or eastern range of the Cordillera. On the coast no fos- 

 sils definitely older than the Carboniferous have yet been detected. In the 

 interior plateau, fossils referable to the Miocene, low^er Cretaceous, Alpine 

 Trias and Carboniferous have been rather sparingly found, while in the 

 mountain region of the Gold system, including the Selkirk, Purcell, Colum- 

 bia and other ranges, we are as yet almost entirely without paleontological 

 evidence. 



Surveys in the Interior Plateau Region. — The writer has been engaged for 

 some time in a detailed examination of an, area of about 6,400 square miles in 

 the interior plateau region, the materials for a geological map of which have 

 now been obtained and are in course of elaboration. In connection with 

 this work, and more particularly to assist in explaining the complexities of 

 the older rocks of this area, it became desirable to ascertain, so far as pos- 

 sible, the relations of these rocks to those of the Rocky Mountains proper, 

 across which one line of section has already been carefully worked out by 

 Mr. R. G. McConnell. 



With this object in view a preliminary examination was made last autumn 

 across the intervening Selkirk range, on the line of the Canadian Pacific 

 railway. This examination was necessarily confined to the vicinity of the 

 railway and still requires to be supplemented by much detail, to be obtained 



