44 
ALASKA GEOLOGY 
The stream tributaries could be seen to come down from 
the hills in the background, which seemed from the ship 
to be quite modern volcanoes and to retain the crater 
form. We had not time to reach these hills over the 
tundra, but the large and half-worn fragments of an erup¬ 
tive rock which we found in the bed of the stream seemed 
certainly to come from them. 
The rock is an amphibolite derived from an eruptive 
pyroxenite(i77). 
v,? 
Ijjggf It is of a dull pale 
greenish color, is 
full of rtist- 
stained fissures, 
and though evi¬ 
dently altered 
shows remains 
FIG. II. COAST OF PORT CLARENCE, ALASKA. 
of broad augite cleavage surfaces. Under the micros¬ 
cope appear cores of pale amber augite mostly changed 
to a fine felted mass of actinolite needles. There are 
many grains of titaniferous magnetite bordered by broad 
bands of fine opaque white leucoxene. The broad patches 
of augite show no trace of intervening feldspar. 
Another slide shows that some of the same material 
has been further changed into isotropic serpentinous matter 
full of rhombs of dolomite. 
The rocks exposed in the cliff along the shore are slates 
of the Vancouver Series, to be described below. 
THE VANCOUVER SERIES 
A series of dark slates, sandstones, greywackes, tuffs, 
and subordinate calcareous beds, often strongly cleaved, or 
jointed all to pieces, and filled with quartz veins, but 
otherwise not greatly advanced in metamorphism, is 
widely distributed in Alaska. It extends from Vancouver 
Island on the south, past Sitka and Glacier Bay to 
