4 8 
ALASKA GEOLOGY 
of the slates in this region appeared to be quite constant, 
indicating only a moderate degree of shattering of beds 
that are essentially in place. 
It will be seen that neither for this place nor for Silver 
Bay are we able to accept the ingenious theory of a pyro¬ 
clastic diorite advanced by Dr. Geo. F. Becker. 1 
At the hot springs on Baranof Island near Sitka the 
country rock is a highly metamorphic sandstone, often 
schistose, and even gneissoid in appearance. It is inti¬ 
mately penetrated by dikes and massive intrusions of 
granite, which has caused, at least in part, the greater 
metamorphism. These dikes often run along the strike 
of the sandstone, causing much contortion of the beds, 
and many fragments of schistose sandstone are included 
in the granite. 
Mr. Devereux and Mr. Palache visited the Chicago 
mine, on Baranof Island, one and one-half miles from the 
head of Silver Bay, and at 1,400 feet elevation. The ap¬ 
proach was over the same grits, greywackes, sandstones, 
and thin shaly bands. The mine is a development tunnel 
only. The quartz body is said to be continuous for three 
or four miles, and consists of a banded bluish quartz or 
chalcedony with lenses of pale pink rhodonite. The 
outcrop is black with manganese stains. The walls 
are slate and greenstone. The mineral content of the 
quartz seems small, chiefly scales of pyrite and pyrrhotite. 
Mispickel is found in the slate near by. Quartz veins, 
bunches and stringers occur quite abundantly in the 
slate. 
Mr. Gilbert climbed to the summit of Mount Verstovia, 
2,800 feet high, directly back of Sitka, and found the same 
conglomerate and sandstone all the way to the top. 
1 Gold Fields of Alaska, 18th Ann. Rep. U. S. Geol. Survey, pt. 111, p. 43. 
1898. 
