tiNDLE.] GEOGRAPHIC DESCRIPTION. 21 
bout 6,000 feet, the same ;is that of Glacier Mountain; ii has several 
larp, precipitous peaks, and the northern slopes arc deeply fur- 
owed by minor streams. The country to the north is one of open 
alleys and broad interstream areas, where the minor lines of drain- 
ge have been gathered into a few main streams which flow in a 
ortherly direction toward the Yukon. 
The most important streams between the Seventymile and Birch 
reek are Flat Creek and Charley River. The former, which is about 
1 miles west from the mouth of Flume Creek, on the Seventymile, 
ows in a canyon within an older valley like that of the Seventymile. 
nt is a much smaller stream. Charley River, which is 8 miles farther 
est, is of the Birch Creek type. It meanders in a narrow canyon 
pout 500 feet deep, the course of which is northeasterly toward the 
Fukon. The river, which rises far in the interior, has a width in this 
>wer portion of its course of 200 to 800 feet, can be easily forded on 
lot at low water, and is said to be navigable for small boats for a 
istance of 100 miles above its mouth. 
BIRCH CREEK REGION. 
General character. — This region, situated about 50 miles south of 
le Yukon at Circle, is shown on the reconnaissance map of the Birch 
'reek and Fairbanks districts (PL XIII). The general characteris- 
es of prominent ridges, less prominent isolated domes, and an undu- 
iting plateau surface deeply incised by many streams are the same 
3 in the Fortymile region. Here, however, the ridges descend to 
le surface of an extensive flat about 800 feet above sea level and 
miles in width, which extends from their base to the Yukon. 
'his ill-drained area is necked with lakes and crossed by the mean- 
ering drainage from the plateau. A prominent ridge, similar to 
iat of Glacier Mountain, can be seen from the plateau level about 
miles to the west. The most prominent domes are Mastodon and 
'orcupine, 4,400 feet and about 4,900 feet, respectively, situated 
bout 8 miles apart, near the area of economic interest. 
Birch Creek system. — The creeks of importance all belong to the 
rainage system of Birch Creek, a stream comparable with Forty- 
lile Creek, which receives many active tributaries ramifying far 
ithin the plateau, and, after flowing parallel with the Yukon in a 
>ng meandering northwesterly course, finally joins that stream below 
:ie great bend at the Arctic Circle (map, PL XVI). It is formed 
y North and South forks (which have southeast and northwest 
ourses, respectively, to the point of union, just within the edge of 
le plateau) and flows northward through a narrow canyon into 
le Yukon flat. North Fork, which is the more powerful stream, 
rains a large area to the west and south, the headwaters inter- 
