700 INDEX TO THE STRATIGRAPHY OF NORTH AMErIcA. 



the scarcity of fossils and to the fact that the La Biche shales pass downward from 

 the Montana into the Colorado without any structural break or lithologic change 

 of any kind." 



The Smoky River shales of the Peace River section are the equivalents of the 

 upper part of the La Biche shales of the Athabaska section. They are dark-grayish 

 to bluish-black shales, 200 feet thick, with bands of ironstone. The fossils belong 

 to a typical "Pierre and Foxhill fauna." 



The Dunvegan is a littoral formation which is lacking in the east and thickens 

 westward from 100 feet on Smoky River to 600 feet at Dunvegan and 2,000 feet at 

 Table Mountain, on Peace River. It consists of sandstone and arenaceous shales 

 and carries fresh-water, brackish-water, and marine fossils, evidence of estuarine 

 conditions and deposition on an oscillating surface. It occupies the stratigraphic 

 position of the Belly River series of Assiniboia and Alberta, but the Belly River 

 does not contain any marine fossils. The fauna of the Dunvegan is said to be like 

 that of the Bear River formation of Wyoming, inasmuch as it contains "two of 

 the most characteristic species of the Bear River, Corbula pyriformis and Corbicula 

 durkeii," but Stanton " does not consider the likeness established by these species. 

 The Dunvegan overhes the Colorado, whereas the Bear River underlies it. 



The beds of the Peace River section which are assigned to the Colorado com- 

 prise about 1,500 feet of shale and sandstone, constituting three named formations. 

 The Fort St. John, is 700 feet thick, the Peace River is a lens which thins out east- 

 ward, and the Loon River is about 400 feet thick. The Loon River apparently 

 rests directly on the Devonian. 



In the parallel Athabaska section the corresponding formations that make 

 up the Colorado are 930 feet in thickness. Compared with the Peace River section 

 the divisions are stratigraphically equivalent as follows: La Biche (lower part) = 

 Fort St. John; Pehcan sandstone and shale and Grand Rapids sandstone = Peace 

 River sandstones; Clearwater shale = Loon River shale. 



McConnell says : ^"° 



The Tar sands underlying the Clearwater are assigned to the Dakota on lithologic and 

 stratigraphic evidence, as no fossils were found in them. They rest on Devonian limestones 

 and occur in the same position as the sands of undoubted Dakota age, which outcrop along the 

 eastern edge of the Cretaceous in Manitoba and south of the international boundary in Minne- 

 sota. They consist of an almost homogeneous mass of tar-cemented sands, ranging in texture 

 from a coarse silt to a grit, and vary in thickness where fully exposed from 140 to 220 feet. 



P 8. LEWES BIVEB, YUKON PROVINCE. 



Rocks of Cretaceous age, both igneous and sedimentary, are described by 

 Dawson ^^ as occurring along the Lewes and other valleys of the inner Coast Ranges. 

 He says : 



Besides the Triassic rocks previously referred to, the Mesozoic period is represented also by 

 strata of Cretaceous and Laramie age. These rocks are distinctively more recent in appearance 

 than and rest qioite unconformably on all the older formations, though they have since been to 

 some extent involved in their flexures. On the lower part of the Lewes, below the mouth of the 

 Little Salmon, these rocks are cut across by the river for a distance of at least 35 miles. Some 



1 Personal statement. 



