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 



