306 Scientific Intelligence. 



From this pamphlet we quote at some length below. It con- 

 tains a brief historical introduction and reference to available 

 literature ; a geographical sketch describing the region, the rivers, 

 climatic conditions and routes to the Klondike. Then follow some 

 twenty pages sketching the geological features. The latter 

 are more elaborately described in the second and third reports 

 named, by Messrs. G. F. Becker and J. E. Spurr, and the coal 

 deposits are described in Mr. Wm. H. Dall's report. 



The original deposits of gold, or quartz veins have been noted 

 in the coastal region as well as in the interior. 



" At present, so far as known, it is only in the coastal region 

 that deep mining is being carried on in gold-bearing veins. Here 

 it has become a well-established industry, and many large quartz 

 mills are running on the ore extracted from these veins. The 

 principal deposits are found in a belt somewhat over 100 miles in 

 length on the seaward slope of the mainland, reaching from Sum- 

 dum on the southeast past Juneau to Berners Bay near Seward 

 on the northwest. This belt may be also considered to include 

 the deposits on Admiralty and other islands. A second belt, 

 further west, is represented by the deposits on the western side 

 of Baranof Island, not far from Sitka. The ores, though not 

 always exceptionally rich, are worked at a good profit because of 

 the natural lacilities of the region for cheap reduction. The most 

 notable instance of this is the great Alaska-Treadwell mine, which 

 has extracted over seven million dollars' worth of gold from an 

 ore carrying $3.20 a ton, which is worked at an average cost of 

 $1.35. 



The deposits occur in metamorphic slates, diabases, and gran- 

 ites, all similar to the rocks of the auriferous belt of California, 

 and probably, like those, they are of post-Jurassic age. 



At Uyak Bay, on Kadiak Island, gold deposits in slates are 

 being worked, and the gold bearing beach sands of the western 

 end of that island and at Portage Bay and the Ayakulik River 

 on the neighboring mainland are apparently derived from meta- 

 morphic slates associated with granite, so that it is possible that 

 these more recent gold-bearing rocks extend that far westward. 

 On Unga Island, of the Shumagin group, still further west, gold 

 occurs in eruptive andesites of Tertiary age, and several mines 

 have been opened on these deposits, the most important of which 

 is the Appollo, one of the most successful in the province. . . . 



In the Yukon Basin the gold, so far as known at present, is 

 derived from a much older series of rocks, for the gold-bearing 

 slates of the coastal region have not yet been recognized there. 

 While the exact age of these gold-bearing rocks has not yet been 

 determined, they are known to be older than the limestones sup- 

 posed to represent the Carboniferous and Devonian formations of 

 the Cordilleran system ; hence they are probably pre-Paleozoic, 

 and in part are possibly as old as the Archean. 



These rocks have been classified by Spurr as follows : 



