LODE MINING IN SOUTHEASTERN ALASKA. 49 
later and more intense folding of the beds, has a northeasterly axial 
trend and is prominent in the less disturbed and less metamorphosed 
areas. In many places both directions of folding are observed, 
those having the northeasterly trend being represented by a number 
of minor folds, which as a whole are combined in much broader anti- 
clines or synclines having a northwesterly trend. Observations of this 
sort were made along the north shore of Chichagof Island and the 
west coast of Prince of Wales Island. 
MINERALIZATION. 
The direct relation of mineralization, or the occurrence of ore, to 
the rock structure and to the intrusive rocks is very evident. With- 
out exception the ore bodies are found in the vicinity of, or more 
rarely in, the larger intrusive masses, and only in those places where 
the rock structure in general has a northwesterly trend. In a broad 
way the mineralization is confined within contact aureoles of the 
granitic and metamorphic rocks. Along the main Coast Range 
granite belt this contact zone is several miles in width, whereas along 
the outlying granite belts of the islands it is but a few miles wide. 
The larger areas occupied by this intrusive rock, so far as known, are 
shown on the sketch map (PL III), and the positions of the mines and 
prospects are indicated by crosses. 
The most extensive and productive area is the Juneau gold belt, 
which has been irregularly traced along the contact of the Coast 
Range intrusive from Windham Bay to a point 10 miles north of 
Berners Bay, where it enters Lynn Canal, a total length of 120 miles 
and a width of less than 10 miles. 
The Admiralty Island mineral zone starts at a point just north of 
Mole Harbor on the west side of Seymour Canal and may be traced 
northwestward. It includes the Young Bay and Funter Bay deposits, 
crosses Lynn Canal, and is again exposed in St. James Bay and above 
the main forks of Endicott River. Mining and prospecting within 
this zone have been extensive but have met with little success. 6 
In the Sitka mining district a mineral zone begins on the southeast 
shore of Baranof Island and follows in a northwesterly direction 
along the west flank of a large granitic belt which forms the backbone 
of Chichagof and Baranof islands. Five miles above Cape Edward 
this belt enters the Pacific Ocean. Within this mineral zone the 
important deposits are quartz veins of free-milling gold ore. Several 
isuch veins in the Silver Bay region have been mined and have been 
productive in past years, and at the present time the Cape Edward 
prospects are making small shipments of gold ore. 
a Spencer, A. C, The Juneau gold belt: Bull. U. S. Geol. Survey No. 287, 1906. 
b Wright, C. W., A reconnaissance of Admiralty Island: Bull. U.S. Geol. Survey No. 287, 1906, 
pp. 138-155. 
Bull. 314—07 4 
