98 EECONNAISSANOE TX NORTHERN ALASKA IX 1901. 



3IIXERAL RESOURCES. 

 GENERAL STATEMENT. 



Under the head of geology, it 1ms been shown that the rocks forming the moun- 

 tains about the head of the Koyukuk Basin comprise several metamorphic series, 

 namely, the Skajit, Totsen. Fickett, Bettles. Lake quartz-schist, and West Fork series. 

 In these mineralization has taken place. It is in the southern part of the region that 

 the efforts of the prospector are being- rewarded, and, in some cases, handsomely. 



Though indications of mineralization occur to some extent nearly all the way 

 northward through the Endicott Mountains, the principal producing region is on the 

 upper parts of Middle and North forks of the Koyukuk. Though the region also 

 contains coal and some lead, copper, and antimony, thus far gold only has proved 

 to be of economic importance. 



GOLD. 



Placer gold has been known in the Koyukuk Basin since the early nineties, if 

 not before. It was first discovered in the bars of the river, of which the most noted 

 seem to have been Hughes and Florence bars, both far below the present placer dig- 

 gings. Tramway Bar, above the sixty-seventh parallel, about 570 miles above the 

 mouth of the river, is among the earliest discoveries. The discovery of Slate, Myrtle, 

 and the other creeks that have been among the chief producers for the last four 

 years was made during and subsequent to the spring of 1S99. These are mostly 

 above Tramway Bar. 



Roughly considered, the Koyukuk gold district, or gold diggings, frequently 

 referred to as the most northern mining camp in the world, as known at present is 

 contained in a rectangular area of about 3,500 square miles, lying between latitudes 

 66° 55' and 67° 55' and longitudes 149° 30' and 151° 20'. a It accordingly trends 

 north and south. Its length is about 70 miles and its width about 50 miles. 

 Diagonally through it from northeast to southwest flows Middle Fork of 

 Koyukuk River, while the northwest portion is drained by North Fork and the 

 southeast portion by South Fork. The principal field of present operations is 

 near the middle of the district, on the middle drainages of Middle and North forks. 



It is only in certain localities in this area, however, that profitable gold placers 

 have been found. The formations on which these placers lie, so far as known, are 

 the Lake quartz-schist, the West Fork schist, the Bergman series, and probably also 

 the Skajit formation, for some of the later discoveries are reported to occur on mica- 

 schist, limestone, and marble:'' but whether any or all of these formations are the 

 original source or mother rock of the gold can not yet definitely be stated, as 

 the season's work afforded no facility for visiting the diggings. The Slate Creek 



a For location and outline of the district, see geologic map. PI. III. 



& On Clara and Emma creeks the country rock is reported to be mica-schist and marble. 



