66 
ALASKA GEOLOGY 
about eight feet thick and parallel to the structure of the 
schist. The aplite has an indistinct schistosity parallel to 
its walls, and shows many films of sericite, doubtless 
formed during the shearing to which it has been subjected. 
The quartz and feldspar of which it is composed, partly 
in indistinct phenocrysts, show strain effects but little al¬ 
teration in the thin section (no. 27). 
This series of greenstone schists, some of which at 
least are clearly derived from igneous rocks, is additional 
evidence of the correctness of Dawson’s correlation of 
the black slate or argillite of Juneau with his Triassic 
Vancouver Series, which in the type locality also contains 
large bodies of metamorphic eruptives. 
