187-6 m. Burmis — Altitude 3,815 ft. (1,162 m.). Near 

 301 km. Burmis a great fault, with a downthrow to the 



east, brings the beds of Lower Cretaceous in 



contact with the upper members. 



THE CORDILLERA.* 



BY 

 S. J. SCHOFIELD. 



CLASSIFICATION. 



The North American Cordillera occupies the western 

 portion of North America from the Great Plains on the 

 east to the Pacific Ocean on the west. 



The size of this Cordillera may be indicated by a com- 

 parison with the other great mountain chains of the world. 

 The Himalayas cover about 300,000 square miles (777,000 

 sq. km.), the Alps of Europe about 70,000 square miles 

 (181,000 sq. km.); the Andes about 1,000,000 square miles 

 (2,600,000 sq. km.); and the North American Cordillera 

 over 2,300,000 square miles (5,961,000 sq. km.). 



The subdivision of this vast orographic unit in Southern 

 British Columbia and Alberta is based upon topographic 

 features, the lines of delineation being the axes of the 

 greater valleys and trenches in the mountain complex. 

 As can be readily conceived from the accompanying 

 illustration, in the easterly Alpine belt, the Rocky Mountain 

 trench, the Purcell trench, the Selkirk valley and the 

 Okanagan valley represent partial boundaries of the Rocky 

 Mountain, Purcell, Selkirk and Columbia Mountain 

 systems. The Western Alpine belt includes the Coast 

 and Cascade ranges, separated from the Vancouver range 

 and the Olympic mountains by the Strait of Georgia. 

 Between these two Alpine belts lies the more subdued 

 Interior Plateau region. 



* Mainly an abstract from Memoir No. 38 by R. A. Daly. Geol. Sur., Can., 1913- 



