GEOLOGICAL A.ND NATURAL HISTORY SURVEY OF CANADA 



CONTRIBUTIONS TO CANADIAN MICRO-PALEONTOLOGY. 



PART IV. 



By Dr. D. Rust, 



(Hanover, Germany. ) 



6. — Radiolaria from the Pierre Formation of North- Western 



Manitoba, 



INTRODUCTIO]^. 



The central portion of the Province of Manitoba is a mcxlerately even 

 phiin, at a mean elevation of about 800 feet above the sea, underlain 

 l)y undisturbed flat-lying limestones and shales, ranging in age from 

 Cambro-Silurian up to Devonian. 



On its eastern side this plain is bounded by the high and often steep 

 escarpment of the eastern face of the Second Prairie Steppe, rising 

 from eight to nineteen hundred feet above the level of the country to 

 the east, and ascending from the former elevation in the vicinity of 

 the International Boundary Line to the latter in the Duck Mountain, 

 two hundred miles further north. 



This escarpment, beneath its capping of glacial deposits, is composed 

 exclusively of the eroded edges of horizontal, undisturbed and con- 

 formable Cretaceous rocks r-anging in age upwards fr<^m the Dakotah 

 sandstone, about the top of the Middle Cretaceous, to high up in the 

 Pierre shales, towards the top of the Upper Cretaceous. The total 

 thickness of Cretaceous beds seen in the district is approximately 1,400 

 feet, and, With the exception of the soft Dakotah sandstone at the base 

 (jf the section, consists entirely of argillaceous shales whicli vary to sonie 

 extent in character in different poi'tions of the series. 



