ALASKA. 35 
Mount St. Elias (18,091 feet) and Mount Logan. The width of the 
range in the vicinity of these peaks is about 100 miles, and the extreme 
height is attained in Mount Logan, in Canadian territory (approxi- 
mately 19,500 feet). Beyond Mount St. PClias the range is divided; a 
subordinate range, called the Nutzotin Mountains, diverges to the north- 
west, and another, the Chugach Mountains, trends southwest across 
the Copper River and down toward the Kenai Peninsula. Between 
these two ranges lie the Wrangell Mountains, Mount Wrangell itself 
being an active volcano. 
Along the western side of Cook Inlet is a range which extends out 
into the Alaska Peninsula and continues through the Aleutian Islands. 
This has been called the Aleutian Range. It is composed largely of 
volcanic material, and embraces a number of active volcanoes. In the 
Cook Inlet region eruptions within recent years have scattered vol- 
canic dust for miles over the surrounding country. 
Farther back from Cook Inlet, to the west, extends the Alaskan 
Range of mountains, with a northeast-southwest trend, which gradu- 
ally bends round to the east and is connected more or less closely 
with the Nutzotin Mountains, an extension from the St. Elias Range. 
This includes many snowy peaks, among which two — Mount Foraker 
and Mount McKinley — stand out above all the others. McKinky^ is 
the loftiest mountain in North America. Its height, which has twice 
been determined by the Geological Survey, is about 20,300 feet. 
The Rocky Mountain system extends through the Yukon Territory 
and approaches the Arctic coast in the northeastern portion of Alaska. 
It then bends toward the west and crosses the northern portion of 
Alaska as a mountainous belt, composed of several ranges, with a mini- 
mum width of about 80 miles and an altitude of about 6,000 feet. 
There is no well-defined crest line. Toward the west it apparently 
becomes two divergent ranges, one of which reaches the coast in the 
vicinity of Cape Lisburne; the other forms the divide between the 
Kowak (or Kobuk) and Noatak rivers. 
Between the Pacific Mountain system and the Rocky Mountain sys- 
tem lies a vast area called the Yukon Plateau. As the mountains have 
been found to be extensions of similar features in the Yukon Territory, 
British Columbia, and the United States, so the great interior basin 
represents probably the northward extension of a similar and related 
feature which in the United States lies between the Pacific Mountain 
and Rocky Mountain systems. 
The traveler between the main drainage areas of the interior is 
struck by the uniform elevation of the interstream areas. Rounded 
hills, level mesas, and persistent flat-topped ridges, composed of rocks 
of varying structure, rise to about the same level, and give the 
impression that they are the remnants of a former continuous surface. 
Occasional limited areas of rugged mountains rise above this level, 
