454 C. SCHUCHERT PALEOGEOGRAPHY OF NORTH AMERICA 



According to King, there were 32,000 feet of Paleozoic sediments in this 

 great syncline. As the faunas of this basin were decidedly Pacific in 

 origin, it must have had free communication with the dominant ocean, 

 seemingly through central California. Southward the Great Basin was 

 often in connection with the Sonoran sea by way of the Arizona basin. 

 To the north this area passed into the Rocky Mountain basin of Wyoming 

 and Montana (Dana, 1890, page 46), and it frequently extended far into 

 the north across Alberta, eastern British Columbia, and western Atha- 

 basca (northern Kocky Mountain trough of Willis, 1907, page 399), then 

 uniting with the Pacific ocean by way of the Mackenzie basin. The 

 latter extended along the valley of the Mackenzie river between Yukonia 

 and Mackenzia. 



In the region of the Kocky Mountain basin the Cordilleran sea often 

 overlapped southeastward across the Dakota states, and connected with the 

 Mississippian sea through the Iowa basin. This was the Dakota basin, 

 first designated by Williams as the "Dakota channel" (1897, page 394). 

 The original definition made this term applicable to Devonic waters hav- 

 ing Pacific-Arctic assemblages of life and in restricted communication 

 with the Mississippian sea. The name, however, is of more general appli- 

 cation for Paleozoic seas repeatedly covering the same common area. Dur- 

 ing Middle and late Ordovicic the Dakota basin was in wide open com- 

 munication with the Mississippian sea, at which time there was a general 

 commingling of northern Cordilleran and Hudson Sea faunas with those 

 of the Mississippian. During the Siluric the Dakota basin connected for 

 ihe last time with the Hudson sea north of the Dakota states, while in the 

 Devonic it stretched far across these states ; in the Mississippic and Penn- 

 sylvanic appearing to be less wide and extending farther south across 

 South Dakota and northern Nebraska. 



Dakota basin. — See Cordilleran sea. 



Exploits channel or trough. — See Saint Lawrence sea. 



Fundy basin. — See Saint Lawrence sea. 



G asp e-W ore ester trough of Dana 57 had no individual development as a 

 seaway, as far as the writer can learn. Its northern end was a part of the 

 Saint Lawrence trough, while the southern portion represented an indefi- 

 nite depression more apparent in the present structure than in the Paleo- 

 zoic seas. It is defined as follows : The trough was situated between the 

 New Hampshire range and the Mount Desert range. It extended "from 

 Gaspe, on the bay of Saint Lawrence, over much of northern New Bruns- 

 wick and central Maine, and continued to Worcester, Massachusetts." 



Great Basin. — See Cordilleran sea. 



5T Dana : American Journal of Science, vol. 39, 1890, p. 380. 



