54 
ALASKA GEOLOGY 
of brown sandstone much cut by small veins. They 
contain a few of the fossils found elsewhere in the 
series. 
The main rock is a dark grey, very thinly fissile argillite, 
not greatly removed from a shale, and often containing 
fossils. It is satiny, from a delicate corrugation in the 
laminae on which the fossils lie, and perfectly jointed. 
This jointing is in places approximated, and passes into 
a perfect slaty cleavage, on the surfaces of which is de¬ 
veloped a minute crumpling (like the primary one men¬ 
tioned above), across which the color banding runs. 
Some of the shales are calcareous and run into thin beds 
of limestone. They are much cut by quartz veins, which 
are often comby and reach several inches in thickness. 
A careful assay made by my son, E. H. Emerson, found 
only a trace of gold. 
In several cases a curious structure has been formed in 
the fissures. Small cubes and radiating balls (probably 
once of pyrite but now of iron rust) have developed in the 
fissures and on the face of the slate, and around them has 
gathered a rim of white, finely fibrous quartz. This is in 
one case in continuity with an ordinary quartz vein. The 
fibres extend straight out from the pyrite in two opposite 
directions, or in a curve which soon becomes radiate. 
SUMMARY 
It was only at the deserted village at Cape Fox, east of 
Duke Island, that we saw old-looking gneisses compar¬ 
able with the pre-Cambrian or the most highly altered 
Paleozoic rocks in New England. The rocks at New 
Metlakatla may be of the same age. 
Next comes, at two widely separated localities — the 
Muir Glacier, near Sitka, and St. Lawrence Island, off the 
coast of Siberia—a series of coarse crystalline limestones, 
with greywacke and cherty quartzites, which have been 
