694: INDEX TO THE STRATIGRAPHY OF NORTH AMERICA. 



T. W. Stanton comments as follows on the foregoing section: 



The lower part of the strata Dawson referred to the Kootenai in this region doubtless 

 includes some marine Jurassic. (See Whiteaves, Description of a species of Cardioceras from 

 the Crows Nest coal fields: Ottawa Naturalist, vol. 17, 1903, pp. 65-67.) This Jurassic ammo- 

 nite is one of the fossils mentioned by McElroy as occurj-ing in the lower beds of the Kootenai 

 below the coal and plant-bearing horizon (Rept. Geol. Survey Canada, vol. 13, 1900, p. 91a). 



McConnell's description ^"^ supplements that given by Dawson: 



The Cretaceous is essentially a clastic formation and contains beds ranging through every 

 degree of coarseness, from fine-grained fissile shales to heavy conglomerates. 



The lower part of the series consists mainly of beds and bands of flaggy sandstone, alter- 

 nating with dark shales. The shales are usually somewhat arenaceous and pass gradually, 

 by the addition of more sandy material, into pure sandstones. They are also occasionally 

 carbonaceous and in a number of places inclose coal seams, some of which are workable. The 

 sandstone occurs characteristically in somewhat thick beds and is usually coarse grained and 

 soft, but harder quartzitic beds are not altogether absent. It weathers to a dull red color. 

 The bands of sandstone are little persistent and if traced along their strike for any distance 

 are found to break up into subordinate beds, separated by tliin shaly partings, or to pass alto- 

 gether into shales. The upper part of the section contains some conglomerate, in addition to 

 the shales and sandstone. Tliis occurs in massive beds, measuring up to 150 feet in thicloiess, 

 and is composed of rounded siliceous pebbles, with some shaly and calcareous grains, embedded 

 in a hard siliceous matrix. The pebbles are usually small, seldom exceeding an inch in diameter, 

 and the rock passes insensibly into sandstone., The section here is more arenaceous than is 

 usually the case, and there is reason to believe that it occupies a comparatively high position 

 in the series and that the lower part contains a greater proportion of shales. The Cascade 

 River section, a few miles farther north, which is undoubtedly lower, shows no conglomerate, 

 a,nd the sandstones are also of less importance, and in nearly every case where beds of Creta- 

 ceous age overlie the Banff limestone in an undisturbed condition, showing that the base of the 

 formation is present, they consist almost entirely of dark shales. 



ilfi ^ :^ ^ ^: ii: ^ :i: ^ 



The following fossils were collected near the base of a small Cretaceous outlier situated 

 3 miles north of the east end of Devil's (Minnewanka) Lake: Oxytoma mucronata, Trigonia inter- 

 media, Trigonoarca tumida," all three characteristic of the Queen Charlotte Island series, and 

 species of Terebratula, Ostrea, Camptonectes, Lima, Cyprina, ammonites, and belemnites. 



A small collection, obtained from the shales faulted under the Cambrian limestones at 

 the gap of the south fork of Ghost River, ■ includes amongst others, such Benton species as 

 ScapJiites ventricosus and possibly S. warreni, and an Inoceramus like 7. undahundus. 



McEvoy ^^* gives a detailed section of 4,736 feet of Cretaceous beds in the 

 Crows Nest Pass basin near Morrisey and notes 1,000 feet or more of shaly limestone 

 and calcareous shales below the measured section, as well as 4,000 to 5,000 feet of 

 soft shale and sandstone above it. He concludes that the total thickness of Creta- 

 ceous strata in the Crows Nest Pass basin is 12,000 to 13,000 feet. 



M 12. NORTHWESTERN MONTANA. 



In northwestern Montana, at the eastern base of the Rocky Mountains, Creta- 

 ceous strata form the valley floors and foothills. In a reconnaissance survey in 

 1901 Willis *•"* distinguished Dakota, Benton, and Laramie. 



a "Most probably Jurassic" [Fernie shale].— T. W. Stanton. See also statement by D. B. Dowling in Bull. Geol. 

 See. America, vol. 17, 1906, p. 298. 



