INTERPRETATION OF ENVIRONMENTAL CONDITIONS 



189 



In the northwestern part of the continent this uplift was approximately 

 paralleled in time by a disturbance which started in Alaska and advanced 

 to the south as far as northern California. Pirsson and Schuchert^ say of 

 this latter disturbance: 



"While it appears that the greater part of the continent was not undergoing 

 more than crustal warping in Pennsylvanian time, there seems to have been more 

 decided unrest along the entire Pacific area from northern California into arctic 

 Alaska. Here the limestones and calcareous shales of the Pennsylvanian and 

 the early Permian are interbedded with much extrusive igneous material. The 

 thickness in California is not less than 4,600 feet, with a maximum of 10,000 feet, 

 while in the Copper River region of Alaska it is nearly 7,000 feet. The calcareous 

 deposits often abound in fossils unrelated to those found elsewhere in North 

 America; they are of the Pacific realm, while the life record of the eastern seas 

 accords better with that of northern Europe, though in the main it is best regarded 

 as constituting the North American province. Long after Pennsylvanian time 

 had begun there was also decided crustal movement in western Colorado, Utah, 

 and Arizona, and this is probably to be associated with the deformation of the 

 Pacific border." 



As shown in the summary description of Alaska, the limestones and cal- 

 careous shales of Alaska, British Columbia, and the Pacific coast involved 



Table 3. — Abbreviated correlation table showing the rise of the red deposits from east to west in the stratigraphic 

 series. Red beds or equivalent intervals lie above the horizontal lines in the table. 



in this movement are not higher than the Russian Gschelian, and so earlier 

 than the time of the formation of the red beds in the Western and Basin 

 Provinces. Red beds and their equivalents, the Park City formation, can 

 be traced into Montana, but the union of the two earth-movements seems 

 to have raised the land north and west of this above the plane of deposition 

 before the red-bed conditions (Triassic) reached that far west. 



2 Pirsson and Schuchert, A Text-Book of Geology, p. 744, 191 5. 



