AGKICULTUKAL DEVELOPMENT IN ALASKA. 3 
that forms the drainage area of the Yukon River and is occupied by 
innumerable detached mountains and mountain masses. There are 
no extensive level plains and very little level land, this being limited 
to the alluvial bottom lands along the larger streams, notably the 
Yukon Flats. 
The northern or Arctic mountain system, most clearly defined in 
the Endicott Range, is a continuation of the Rocky Mountains, the 
Continental Divide, which, continuing northwestward through 
Canada, reaches the northern coast of the continent near the boundary 
between Canada and Alaska, and then swinging sharply to the west 
extends across the northern portion of Alaska. The altitudes in this 
system within Alaska are not high, the maximum being not more 
than 6,000 feet, with the result that there is but a small perpetual 
snow and ice field. The northern slope toward the Arctic Ocean is a 
barren and for the most part unexplored wilderness. It is drained 
by a number of large rivers. 
The Pacific mountain system, which fronts the south coast of 
Alaska, demands more attention, for it is not only that which has 
developed public opinion regarding Alaska, but it is the dominating 
physical factor. It is the extension of the Coast Range of the 
United States, with which the Sierra Nevada coalesces in northern 
California and continues northward through Oregon and Washing- 
ton as the Cascade Mountains. North of Puget Sound the sea has 
broken into the mountain fastnesses along a 1,000-mile stretch until 
the St. Elias Range is reached, where, with increasing height, the 
sea is forced back outside of the coast line. Northwestward from 
Mount St. Elias the range widens into a system, with the Chugach 
and Kenai Mountains immediately on the coast, and back of these 
the Wrangell and Nutzotin Mountains. These, with the minor 
ranges, merge into the Alaskan Range that swings southwestward 
and continues out on the Alaska Peninsula as the Aleutian Range, the 
whole mass forming the arc of a great circle. The system, extend- 
ing in width from the water's edge to 200 miles back from the coast, 
is of great altitude, the maximum being Mount McKinley, in the 
Alaskan Range, 20,464 feet. Mount St. Elias is 18,024 feet high, and 
Mount Blackburn, in the Wrangell Mountains, is 16,140 feet. 
Right here in this mountain mass, occupying an area 200 by 
400 miles in extent, is the dominating fact that always must be borne 
in mind when studying Alaska, namely, the effect on the moisture 
with which the warm air currents from the sea are laden. Striking 
the cold breasts of these high mountains, the moisture in the air is 
condensed and precipitated as snow on the high levels and as rain 
lower down, 90 inches being the average annual precipitation at 
Sitka, while at a number of points on the coast in southeastern Alaska 
