22 FORTYMILE, BIRCH CREEK, AND FAIRBANKS PLACERS, [bull. 251 
locking with (hose of streams tributary to the Tanana. South 
Fork, (') miles to the southeast of the main forks, divides into twoi 
strong tributaries, and these rapidly split up into numerous smaller 
streams which are deeply sunk within the region and interlock with 
the system of the Charley River to the east and southeast. The val- 
leys of the two main forks are bounded to the north by a steep slope 
rising 1,000 feet or more above them. A well-defined bench about 
100 feet above the present streams bounds the narrow valleys to the ij 
south, and extends, with a gradually rising slope, to the foot of theJ 
spurs which lead to the higher ridges. About 5 miles north of thl 
hills Birch Creek is joined by Crooked Creek, which flows in am 
easterly direction through a broad, flat valley and receives the waterij 
of several short, northward-flowing streams of economic importance,', 
which drain the edge of the plateau. The wide flat of Crooked Creelda 
merges into that of Birch. 
The valleys of Mission Creek, Seventymile, and of the forks off 
Birch Creek are similar in that they have an unsymmetrical section-ll 
steep slopes on the north and an open, more or less benched country^ 
to the south. 
■ 
FAIRBANKS REGION. 
General character. — This region occupies a position on the southt! 
border of the plateau country corresponding to that of the Birch ij 
Creek region on the north, and is also shown on the reconnaissance^! 
map of the two districts (PI. XIII). The area in which there isH 
present interest lies between Little Chena and Chatanika rivers, and li 
is drained b}^ their tributaries. The general character of the region 4 
is the same as that of Birch Creek, except that the plateau regionnj 
descends more gradually to the valley of the Tanana and has someM 
what lower average altitude. Domes which have received local names i 
rise above the general level to a height of 2,600 to 3,000 feet above e 
sea level. The valleys are more open than those to the north and thai 
divides separating them are lower. 
Chatanika and Chena rivers. — The Chatanika has its source far I 
back in the plateau, and flows in a southwesterly direction to the* 
Tanana. Twenty miles to the east is the Little Chena, which flows 
in a course parallel to the Chatanika and joins the Chena in the 
flats a few miles south of the plateau. The divide separating the 
Chatanika and the Little Chena extends in a southwesterly direction h 
parallel to their courses and has been much dissected by minor tribu- 
taries, which How to the northwest and the southeast, respectively, 
toward these streams. The occurrence of gold on these small streams 
has made the area one of economic importance. The distance 
