624 INDEX TO THE STEATIGRAPHY OF NORTH AMERICA. 



Slate Creek and Ruby Creek are much older than the Cretaceous." * * * The authors do 

 not consider that the assumption of the pre-Cretaceous age of these beds is justified and have 

 provisionally considered them as belonging in the same formation with those at Barron. 



To the rocks of this locality which he recognized as Cretaceous Prof. Russell provisionally 

 applied the name Similkameen formation.* This name was, however, applied ten years earlier 

 by Dawson to a Miocene formation in British Columbia."^ * * * 



The Pasayten formation is composed of sedimentary rocks without contemporaneous vol- 

 canic materials. East of the main fork of Pasayten River sandstone appears to be the domi- 

 nant rock. * * * The lowest part of the section, as seen along the crest of the Hozomeen 

 range, includes at least 1,000 feet of black shale. Above this shale is a sandy conglomerate, 

 with pebbles from 1 to 8 inches in diameter. * * * Sandstone overlies the conglomerate 

 and is succeeded by more black shale. The steep dips here indicate the presence of a great thick- 

 ness of these rocks, * * * gQ ^];^a^ 6,000 feet would appear to be a very conservative esti- 

 mate for the thickness of the Pasayten formation. 



There are a few thin and discontinuous beds of limestone in the Pasayten formation, but 

 they constitute only an insignificant proportion of its total volume. Along the lower portion 

 of Slate Creek the supposed Cretaceous rocks are mainly black indurated shales with nearly ver- 

 tical dips. 



The argillaceous portions of the Pasayten formation are generally dark-colored, distinctly 

 bedded shales. They are often siliceous and in general more or less indurated, and are popu- 

 larly referred to as "slate." * * * 



The sandstones, while occasionally quartzitic, are more commonly gray or greenish gray in 

 color, and evidently composed in large part of feldspar and rock fragments. The conglomerates 

 contain a variety of pebbles, including several granitoid rocks, gabbro, diabase, metamorphosed 

 volcanics, chert, quartzite, and vein quartz, illustrating the character of the pre-Cretaceous 

 formations of the region. 



The whole series has undergone a considerable degree of "static" metamorphism, as shown 

 by the generally thorough cementation of the sandstones.and the presence of joints in all the 

 varieties of rocks. Both these phenomena are exemplified strikingly in the conglomerates, 

 which often are divided into great blocks whose faces are nearly as smooth as if made by a saw 

 that had cut indifferently through the pebbles and their compact matrix. 



The series is cut by many dikes and sheets of igneous rock; these are especially numerous 

 along the main divide, where they must add materially to the volume of the formation. At three 

 localities there are exposures of granitoid rock, apparently intrusive in the Pasayten formation. 



M 11-12. CANADIAN ROCKIES, ALBERTA AND BRITISH COLUMBIA, d 



The Cretaceous areas in the Canadian Rockies are best known as the Cascade 

 and Crows Nest Pass coal fields. Dawson stated that in this region dark Cretaceous 

 shales in apparent conformity succeed Carboniferous shales, which are lithologi- 

 cally similarj but the Fernie shale (Jurassic) has since been distinguished. The Cre- 

 taceous consists of shales, sandstones, conglomerates, and coals, to a total thickness 

 of 12,000 feet or more. It comprises the Kootenai formation (Lower Cretaceous), 

 a local volcanic intercalation, and Upper Cretaceous strata. Dawson's original 

 description ^^®* runs in part : 



Over the area of the Great Plains, both in the United States and Canada, and in the Rocky 

 Mountain region south of this district, the lowest rocks of the Cretaceous series developed are 

 those of the Dakota, of Middle Cretaceous age. In the vicinity of the west coast Lower Creta- 



a Russell, I. C, op. cit., p. 112. 



b Idem, pp. 114-117. 



c Dawson, J. W., Proc. and Trans. Royal Soc. Canada, vol. 8, sec. 4, 1890, pp. 75-91. 



^ For the Cretaceous of the plains in this latitude see p. 695. 



