﻿SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 74 



north. It is evident that in the ancient and narrow Cordilleran Sea 

 that extended from the Arctic Ocean 2,000 miles (3,218 km.) or more 

 south between the coast ranges of the time and the uplands of the 

 central portion of the North American continent, there was a simi- 

 larity of Lower Paleozoic marine life along the shores and in its 

 shallow waters. Evidences of this and of strong currents and per- 

 sistent wave action occur all the way from central Nevada to Mount 



Fig. 19. — Graptolites that flourished on the muddy bed of the sea in 

 Silurian time. The coiled form Monograptus convohitus Hisinger is found 

 both in Europe and America. The straight form is very abundant in some 

 of the partings of the shale. 



Locality: Sinclair Canyon about 3.25 miles (5.2 km.) above Radium Hot 

 Springs, "in cliff on south side of Banff-Windermere motor road, British 

 Columbia, Canada. 



Robson in British Columbia. The record of the marine life and 

 deposits of mud and sand is most complete, and it has been great sport 

 running down the various clews that have been encountered from 

 time to time. 



The lower Sinclair Canyon opens out into the Columbia River 

 Valley through a narrow canyon eroded in the upturned and faulted 

 limestones. Some conception of the character of the canyon may be 

 obtained from figures 21-23. 



