Mountain Sj/stem and Ranges. 129 



])lateau which occupies the eastern part of White River basin. 

 This region is practically unknown, however, and the precise 

 relation of the Coast range to the St Elias range has not yet been 

 determined. Where the former range is cut through by Taku 

 river its northeastern face, like its northwestern termination, is 

 not sharply defined, but the mountain range merges with the high 

 , plateau lying to the eastward between the Coast range and the 

 Rocky mountains. 



The 8t Elias range appears to be due to a separate and more 

 recent uplift. Its continuation southward is partially submerged 

 and forms the islands of the Alexander archipelago. Still 

 further southward, in Queen Charlotte and Vancouver islands, 

 it has been called by Dawson the Vancouver range, the western- 

 most member of the Cordilleran system. Like the southern 

 coast range, it is a broad elevated belt with numerous peaks and 

 short ridges, probably the highest being along its southern 

 border, culminating in mount St Elias. Westward from this 

 peak the range is separated into two divergent ranges by the 

 valley of Chittenah river. The one continuing toward the north- 

 west contains the high volcanic peaks of the Wrangell group. 

 The southern divergent range follows the coast toward the west 

 and, bending round Prince William sound, continues toward the 

 southwest in the Kenai j^eninsula and perhaps Kadiak island. 



The eastern limit of the Coast range may be fixed approxi- 

 matel}^ at the junction of the northern and southern forks of the 

 Taku, the region east of this being a high plateau which extends 

 to the Cassiar range, the northern representative of the Gold 

 ranges of British Columbia. The elevation of the interior plateau, 

 where it is crossed tn passing from the Taku to lake Ahklen, is 

 about 5,000 feet above sea level. From this point it descends 

 gradually toward the northwest, its altitude at the junction of 

 Lewes and Pelly rivers being less than 3,000 feet. Southwest of 

 Selkirk the same plateau extends with gradually increasing 

 altitude to the base of the St Elias mountains. It is only in a 

 general way, however, that these areas are to be regarded as 

 plateaus. When considered in detail the surface is extremel}^ 

 rough and broken. The river valleys lie from 2,000 to 2,500 feet 

 below the general plateau level, while broad and rounded dome- 

 like summits and a few sharp peaks rise from 700 to 1,200 feet 

 above it; but there appear to be no well defined ridges or 

 chains of peaks. For about 150 miles southwest of Selkirk the 



