GEOGRAPHY RELIEF. U 
limit of the hill country is less abrupt and the ridges merge gradually into the low- 
lands of the Tolovana. 
The valleys, too, exhibit as much variation as the ridges. There are deep, steep- 
walled canyons which lead away their waters quickly, and there are open spaces 
where the waterways are only slight depressions in a rolling surface having an almost 
imperceptible grade. The streams throughout this country often pursue most irreg- 
ular courses before they finally extricate themselves from the many ridges and become 
identified with their respective drainage systems. The important tributaries of the 
Yukon are Beaver Greek, Hess Creek, and Minook Creek; those tributary to the 
Tanana are Tolovana River and Baker Creek. 
The hill country gives place along an east-and-west line which crosses the Yukon 
a short distance above Fort Hamlin to one of the most striking features in the interior 
of Alaska — Yukon Flats. From the base of the overlooking ridges, 1,500 to 2,000 
feet above them, they extend northward toward the plateau country fronting the 
Rocky Mountains and eastward far out beyond the sky line. The sparsely timbered 
surface is somewhat uneven and broken where minor ridges run out into it from the 
base of the hills. It is dotted with a few small lakes, and the minor streams which 
furrow deeply the northern slopes of the hills run irregularly across it in no well- 
defined valleys of their own. Through it all can be seen long lines and crescent- 
shaped areas of water where the many interlacing channels of the Yukon spread 
widely over the great surface. The lowlands along the southern border of the hill 
country, the Tolovana and Baker fiats, although occupying large areas, are local 
features less sharply differentiated from the hills and more closely related to their 
respective drainage systems. 
RELIEF. 
The distance in a straight line from a point on Chatanika River about opposite the 
mouth of Cleary Creek to Yukon Flats is about 60 miles, and the section may be 
roughly divided into three parts — the country from Chatanika River to Beaver 
Creek, the White Mountains in the space between the two parts of Beaver Creek, 
and the ridge country between the northern part of Beaver Creek and Yukon Flats. 
A space 20 miles wide between Chatanika River and Beaver Creek is occupied 
by the broad ridge which separates the tributaries of the two streams. This ridge 
extends in a northeast and southwest direction and has an elevation of about 1,000 
feet above the valleys on each side. It is very unsymmetrical. The southeast slope 
is rather steep and is worn by short tributaries of the Chatanika into minor lateral 
spurs, which descend abruptly to the valley. The northwest slope presents a strik- 
ing and unexpected contrast. Long, broad, lateral ridges extend their dark, spruce- 
clad, undulating surfaces with gradually diminished height toward the steep-sided 
serrate ridges of the White Mountains and finally 15 miles away merge into the open 
valley of Beaver Creek. These ridges, so uniform in height and even in outline, are 
separated by wide, shallow, sparsely timbered valleys of equal uniformity, occupied 
by small, weak streams which flow with gentle gradients for several miles to Beaver 
Creek. 
The White Mountains (PI. II, A, p. 10), as seen from the highest parts of this 
ridge, rise abruptly from the somber foreground which extends with apparent con- 
tinuity to their base, and not till the explorer reaches the edge of Beaver Valley does 
he understand their true relation to it and to the country to the south. They extend 
in a northeast and southwest direction a distance of 50 or 60 miles and form perhaps 
the most persistent group of ridges in the Yukon-Tanana country. They rise 2,000 
feet or more above the base and increase in height toward the northeast, where some 
of the highest points have an altitude of about 5,300 feet. To the southwest they 
narrow rapidly to a single, knife-edge ridge, which terminates at Beaver Creek about 
35 miles nearly north from Fairbanks. The uneven ridges exhibit a great variety of 
