124 G. M. Dawson — Earlier Cretaceous Rocks 



Cretaceous rocks have been made. At Rink Rapid, on the 

 Lewes River (lat. 62° 20' long. 13t>° 10') and at Lake Labarge, 

 further up on the same river, the writer found fossiliferous 

 Cretaceous rocks which Mr. "Whiteaves regards as probably 

 also the same in age as those of the Queen Charlotte Islands 

 formation.* Mr. McConnell has, further, discovered fossils 

 belonging to the same fauna on Rat River (Rocky Mountains, 

 lat. 67° 10'), on Porcupine River (lat. 67° 28' long. 137° 47') 

 and on the main Pelly or Yukon River (lat. 65° 15', long. 

 141° 40'). The characteristic Aucella above referred to is, 

 however, the only species represented in two of these localities. 

 The various widely scattered observations above enumerated, 

 now enable us to state, that a great earlier Cretaceous forma- 

 tion, beneath the horizon of the Dakota, is more or less con- 

 tinuously developed over a vast tract of country, the eastern 

 edge of which lies to the east of the present line of the Rocky 

 Mountains from the 49th parallel to the Arctic Ocean, and 

 which is represented to the west as far as the vicinity of the 

 mouth of Fraser River, the Queen Charlotte Islands, and in 

 the Yukon Valley beyond the 141st meridian, in the interior of 

 Alaska. Its existence may also be traced on the Alaskan 

 Coast to the peninsula of Aliaska, in longitude 160° 31' or 

 farther. t It is impossible at present to define precisely the 

 eastern margin of this formation, as in the area of the Great 

 Plains sections are very seldom cut down to the base of the 

 Cretaceous. From what is known, however, it appears prob- 

 able that this line lies not far to the east of that of the Rocky 

 Mountains, leading to the inference that some causal connec- 

 tion of an orogenic kind may exist between the eastern limit 

 of these very massive Cretaceous accumulations and the posi- 

 tion of this eastern member of the Cordillera. There is, how- 

 ever, in the southern interior of British Columbia, an extensive 

 tract which includes the Seikirks and associated ranges, in 

 which no Cretaceous rocks have been met with, and which it 

 would appear, on this and other grounds, has been a land area 

 throughout the Cretaceous period and a mountain system ante- 

 dating those of the Rocky Mountains proper, the Coast Ranges 

 o of British Columbia and the Cascades of Oregon and Washing- 

 ton, in the flexures of which ranges Cretaceous rocks are in- 

 volved. It is further probable that other yet undefined insular 

 areas existed in the Cordillera region to the north and west, 

 but the evidence now available shows, that to the north of the 

 54th parallel, in both the Triassic (" Alpine Trias ") and Cre- 

 taceous periods, the Pacific spread eastward in a more or less 



* Annual Report, Geol. Surv. Can., 1887, pp. 146 B., 159 B. 

 + By collections made by Mr. W. H. Dall and others as detailed by Dr. C. A. 

 White in Bulletin U. S. Geol. Survey, No. 4, 1884. 



