574 INDEX TO THE STRATIGRAPHY OF NORTH AMERICA. 



M 11. SOUTHWESTERN ALBERTA. 



The Fernie shale, which was originally included by Dawson in the Cretaceous 

 as part of the Kootenai formation, has been separated and is described by Dowling.^^^ 

 In the Cascade coal basin. Alberta, it consists of black shales with gray sandstones 

 and local limestone beds which occupy the same position relatively to the Kootenai 

 of the older rocks beneath as a similar series at Fernie, where there are Jurassic 

 fossils. The thickness is given as approximately 1,600 feet. 



The relations of the Jurassic and Lower Cretaceous of British Columbia are 

 discussed in Chapter XIV (pp. 624-630). 



M-O 9-10. WESTERN BRITISH COLTIMBIA. 



Dawson's descriptions of the "Porphyrite group" (Jurassic?) are given in 

 Chapter XIV (p. 627). 



O -^5. ALASKA PENINSULA. 



The Alaska Peninsula is composed largely of Mesozoic rocks, which, though 

 known to comprise several terranes, have not yet been separated in mapping but 

 are grouped under the color which indicates Jurassic. Brooks ^°^^ gives a general 

 account of the history of investigation of these strata. The latest and most com- 

 plete study of the section as yet made is that of Stanton and Martin, ''^'^^ to whose 

 account reference should be made for detailed sections and a statement of the 

 stratigraphic relations, which they sum up as follows: 



The Mesozoic section of southwest Alaska includes representatives of the Upper Trias, 

 Lower, Middle, and Upper Jurassic, Upper Cretaceous, and probably Lower Cretaceous. 



The Jurassic shows the greatest development, both stratigraphicaUy and faunally, and is 

 probably unequaled in these respects elsewhere on the American continent. The total thickness 

 can not be much less than 10,000 feet, and the areas covered by the upper half of the Jiirassic 

 are large. 



The faunal type is essentially Russian — that is, boreal — though it differs in the common 

 occurrence of PhyUoceras andLytoceras at several horizons. The succession of the faunas 

 from the Callovian to the top of the Jurassic is the same as in Russia, but the vertical thickness 

 of beds through which each ranges appears to be very much greater in Alaska. 



The Cretaceous and Triassic rocks so far as now known occur only in small scattered areas, 

 and their faunas may be directly correlated Avith those of formations in California and elsewhere 

 on the Pacific coast. 



The general relations of the formations may be epitomized in the following section: 



Tertiary. — Kenai formation. Shales, sandstones, and conglomerates with several heds of coal. The entire formation 

 nonmarine and characterized by a large flora. Thickness, ±2,000 feet. 



Unconformity. 



Upper Cretaceous. — Lithologically similar to the Kenai, but including some marine shales and sandstones with an Upper 

 Cretaceous fauna. Thickness, d= 1,000 feet. 



Unconformity. 



Lower Cretaceous. — (Not seen within the area studied.) Shales and sandstones with Aucella crassicollis. 



Unconf ormity( ?) . 



Upper Jurassic. — Naknek formation. Conglomerate, arkose, sandstone, and shale with interstratified andesite flows. 

 Thickness, about 5,000 feet. 



Middle Jurassic. — Enochkin formation. Shales and sandstones with some conglomerate beds. Thickness, 1,,500 to 

 2,500 feet. 



Unconformity(?). (Possibly conformable on Lower Jurassic when that is present.) 



Lower Jurassic. — Tuffs and sandstones. Thickness, ±1,000 feet. 



Unconformity. 



Upper Triassic. — Thin-bedded cherts, limestones, and shales usually much folded and contorted and with many intru- 

 sive masses. Thickness, ±2,000 feet. 



Base not seen. 



