BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 1, pp. 395-410 April 17, 1890 



POST-TERTIARY DEPOSITS OF MANITOBA AND THE AD- 

 JOINING TERRITORIES OF NORTHWESTERN CANADA. 



BY .7. B. TYRRELL, OF TIIL GEOLOGICAL SURVEY OF CANADA. 

 [Read before the Society December 27, 1889.) 



CONTENTS. 



Page. 



The Region and its General Geological Features 395 



The Glacial Deposits 396 



Till 396 



Terminal Moraines 398 



Absence of Terminal Moraines near the Rocky Mountains 401 



Western Pebbles 401 



Direction of Ice Flow 401 



Deposits of Isolated Glaciers 402 



Drumlins 402 



The Aqueous Deposits 402 



Interglacial Deposits 402 



Karnes t03 



Lacustral Beds 403 



Ancient Beaches 404 



Discussion 40 



The Region and its General Geological Features. 



Southwest of the margin of what has loug been known as the Arcliean 

 continental nucleus lies a great drift-covered area, including in it most of the 

 plains and prairies of northwestern Canada. It extends on the international 

 boundary line from the western side of the Lake of the Woods to near the 

 eastern base of the Rocky Mountains, through between sixteen and seven- 

 teen degrees of longitude, or a distance of more than 750 miles. Towards 

 the northwest it stretches along the face of the Archean area to beyond the 

 arctic circle in the valley of the Mackenzie river. 



Lying on an irregular floor of old gneisses and schists, rocks of Silurian 

 and Devonian age are known to occur over the whole eastern and north- 

 eastern portion of this district, while further westward these disappear under 

 others of upper Mesozoic age ; and thence westward to the foot of the Rocky 



LII— Bum.. Shot- Soc. Am., Vol. 1, 1889. (39- r >) 



