42 DEPARTMENT OF THE INTERIOR 



2 GEORGE V., A. 1912 



the main divide of the Cascades in the vicinity of Barron. The highest 

 peaks, such as Chopaka, Cathedral, Kemmel, and Bighorn, have a nearly 

 uniform elevation of 8,000 to 8,500 feet and commonly are extremely 

 rugged. Over the larger portion of this area the heights are above 7,000 

 feet, and below this are the deeply cut valleys.' 

 The respective east and west limits of the three ranges are clearly and 



definitely fixed by the longitudinal valleys of the Similkameen, Pasayten, and 

 Skagit rivers, and by the partially filled depression of the Strait of Georgia. 



The northern and southern limits cannot at present be determined; that further 



step may be made when, in the future, the cartography of the rugged system 



is completed. (Plate 3.) 



SUMMARY. • 



The writer keenly feels the responsibility of suggesting many of the 

 changes and additions proposed in the cartography of this large section 

 of the Cordillera. The attempt to describe the geology of the Boundary belt 

 without some kind of systematic orography on which to hang the many facts of 

 spatial relation, is truly the making of bricks without straw. The scheme 

 outlined above has thus developed out of a clear necessity. 



The orography of the International Boundary cannot profitably be treated 

 without reference to longitudinal Cordilleran elements, often running many 

 hundreds of miles to northward and southward of the Boundary. For this 

 reason the accompanying map is made to cover all of the Cordillera lying 

 letween the forty-seventh and fifty-third parallels of latitude. (Plate 3.) 



The terms ' range ' and ' system ' are used in their common elastic mean- 

 ings, with ' system ' more comprehensive than 'range.' The Cordilleran 

 system, or Cordillera, includes the Pocky Mountain system, the Selkirk system, 

 etc. The Cascade range includes the Okanagan range, Skagit range, etc. A 

 system may include among its subdivisions a mountain group without a decid- 

 edly elongated ground-plan; thus the Columbia system includes the Possland 

 mountains. But both ' range ' and ' system,' used with their respective broader 

 or narrower meanings, involve the elongation of ground-plan and a correspond- 

 ing alignment of mountain crests. The great weight of popular and official 

 usage seems to render it inadvisable to attempt any more systematic organiza- 

 tion of the common nouns in this case. It has been found almost, if not quite, 

 as difficult to organize the proper names in an ideal manner. 



The basis of mountain grouping is purely topographical, and is, in the 

 main, founded on established usage. A primary grouping recognizes within 

 the Cordilleran body two relatively low areas, characterized by tabular reliefs, 

 accompanied by rounded reliefs, generally accordant in altitude with the 

 plateaus. These two areas are the belt of Interior Plateaus in British 

 Columbia and the Columbia lava plain of the United States. The remainder 

 of the Cordillera — ridged, peaked, often alpine — is divided into systems, ranges, 

 and more equiaxial groups, either by ' trenches,' by master valleys, or, excep- 

 tionally, by structural depressions. 



