YUKON PLACER FIELDS. 
128 
resulting from increased facilities in transportation, there is the opportunity everj season of 
working ground containing lower values; there are, further, the potentialities of the unde- 
veloped creeks which have just become producers, and last of all, there are the possibilities 
of new discoveries. The region is not one where unusually large returns are to be expected, 
but one where energetic and intelligent operators may for a long time find a reward. 
SALCHA REGION. 
The stream Salcha of some maps, from which this region takes its name, is known in 
Alaska, as the Salchaket. The shorter form is, however, in accordance with the decision of 
the United States Board on Geographic Names. (See (ig. 8.) During the last year con- 
siderable prospecting was done in this region, which lies .50 to 100 miles east, of Fairbanks, 
adjacent to the north side of Tanana River. The area, is drained by Healy, Volkmar, Good- 
paster, Salcha, and Chena rivers ami by several smaller streams, among which are Shaw, 
Tenderfoot, and Banner creeks. Most of the work has been done on Tenderfoot Creek, a 
Fig. 8— Map of lower Tanana region. 
small tributary of the Tanana, and on Butte -and Caribou creeks, tributaries of the Salcha, 
streams whose valleys are all cut in schistose rocks. 
The bed rock throughout this region consists essentially of schists, gneiss, and horn- 
blende-granite. There is some greenstone and serpentine, which weal hers brownish. The, 
schists are like those of the Fairbanks and Birch Creek regions and include quartzite-schist, 
quartz-mica-schist, hornblende-schist, garnetiferous schist, and crystalline limestone in 
places garnetiferous. The gneisses are probably old granites that have been intruded in 
the schists. 
The eastern extension of the schists of the Fairbanks region is a matter of economic inter- 
est. Though the schist belt is frequently interrupted by intrusive masses of granite of 
greater or less extent, it may be said in general that the valleys of Chena River and its t ribu- 
taries are mostly in the schists, that a large part of the Salcha Valley is in the schists, and 
that to the east the schist belt gradually narrows and is confined to the lower parts of the 
valleys. The area between the Mosquito drainage and Healy River is mostly intrusive 
granite, granite-porphyry, and granite-gneiss, and the schists do not occur except along the 
