UPPER CEETACEOUS. 695 



Laramie sandstone ["]: Sandstone, hard, gray, cross-bedded, and joft, shaly, interbedded, carrying 



layers of oyster shells and containing plant remains. 

 Benton shale: Shale, dark bluish gray, very fissile, fossiliferous, with occasional beds of sandstone, 



medium grained, brown, and thin limestone layers. 

 Dakota sandstone : Sandstone, yellow and brownish, and shale, arenaceous, with plant remains and 



fresh-water shells. 



A recent reconnaissance * by M. R. Campbell and C. A. Fisher shows that 

 the Colorado is exposed in a broad strip extending from the Big Belt Mountains 

 north by west, possibly to or into Alberta. This strip is flanked on both sides by 

 the Eagle sandstone and higher formations of the Montana group, including the 

 Judith River. 



M-N 11-14. PLAINS OF ALBERTA, SASKATCHEWAN, AND MANITOBA. 



Dawson's classification of the Cretaceous strata of the southwestern part of the 

 Great Plains in Canada is given on page 693 in comparison with that of the Cretaceous 

 in the Rocky Mountains. The Athabaska and Peace River sections are described 

 on pages 699-700. 



The standard section of the Upper Cretaceous of Canada was established by 

 Dawson ^^^ in a study of the region between the base of the Rocky Mountains and the 

 meridian of 110° 45', near Medicine Hat, on the South Saskatchewan. Dawson's 

 classification is as follows : 



Laramie: Feet. 



Porcupine Hill beds: Sandstones, frequently thick bedded and generally comparatively soft, 



with intercalated grayish and blackish shales and shaly clays. Fresh water 2,500 



Willow Creek beds: Soft sandstones, shales, clays, and sandy clays, generally with pronounced 

 reddish or purplish tint. Fresh water 450 



St. Mary.River beds: Sandstones, shales, and shaly clays ui frequent alternations, and generally 



well bedded. Fresh water except near base 2,800 



Cretaceous: 



Fox Hill sandstones: In some parts of the district well defined as a massive yellowish sandstone, 

 but inconstant, and apparently often represented by a series of brackish-water transition 

 beds between the Laramie and the Pierre 80 



Pierre shales: Neutral gray or brownish to nearly black shales, include a zone of pale soft sand- 

 stone in the northeastern part of district, and frequent intercalations of harder sandstones near 

 the mountains. Marine 750 



Belly Biver series: Composed of an upper or "pale" and lower or "yellowish" portions and con- 

 sisting of alternations of sandstones, sandy clays, shales, and clays 910 



Lower dark shales: Gray to nearly black shales, frequently with arenaceous shales 800 



Details of occurrence and local character of each of these formations are given 

 in the subsequent pages of Dawson's report and he states his interpretation of the 

 geologic history .^^''^ 



The region east of that examined by Dawson, lying between the meridians of 

 106° and 110° 50', was studied by McConnell,^^* who recognized Belly River, Pierre, 

 and Fox Hill, overlain conformably by the Laramie, and the latter overlain uncon- 

 f ormably by Miocene. 



« "The 'Laramie' of this section is probably Judith River or older. The distinction between Laramie and Judith 

 River was not generally rpcognized when these fossils were examined." — T. W. Stanton. 

 6 Data contributed from manuscript records of the United States Geological Survey. 



