286 Canadian Record of Science. 



coincident, however, with the latitude of the head-waters 

 of the Missouri, a change occurs in the character of this 

 Cordillera region. It becomes comparatively narrow, 

 and runs to the 56th parallel or beyond, with an average 

 width of about four hundred miles only. This narrower 

 portion of the Cordillera comprises the greater part of 

 the Province of British Columbia, and consists of four 

 main ranges, or more correctly speaking, systems of moun- 

 tains, each composed of a number of constituent ranges. 

 These mountain systems are, from east to west, (1) The 

 Eocky Mountains proper. (2) Mountains which may be 

 classed together as the Gold Eanges. (3) The system of 

 Coast Eanges sometimes improperly regarded as a continu- 

 ation of the Cascade Mountains of Oregon and Washington 

 Territory. (4) A mountain system which in its un- 

 submerged. parts constitutes Vancouver and the Queen 

 Charlotte Islands. This last is here actually the bordering 

 range of the continent, as beyond it, after passing across 

 a submarine plateau of inconsiderable width, the bottom 

 shelves very rapidly down to the abyssal depths of the 

 Pacific. The Tertiary coast ranges of the south are here 

 entirely wanting. 



Between the second and third of the above mountain 

 systems is the Interior Plateau of British Columbia, with 

 an average width of about one hundred miles, a mean 

 elevation of about 3500 feet and peculiar character and 

 climate. The present paper refers more particularly to a 

 portion of the Eocky Mountains proper. This system of 

 mountains has, between the 49th and 53rd parallels, a 

 mean breadth of about fifty miles, which, in the vicinity 

 of the Peace Eiver, decreases to forty miles, the general 

 altitude of the range, as well as that of its supporting 

 plateau, at the same. time becoming less. Beyond the 

 Peace Eiver region, these mountains are known only in the 

 most general and unsatisfactory way. The portion of the 

 Eocky Mountains which has been explored, is bordered to 

 the eastward by the Great Plains, which break into a se- 

 ries of foot-hills along its base, and to the westward by a 

 remarkably straight and definite valley which is occupied 



