4 2 ALASKA GEOLOGY 



(/) Ideally fresh small-porphyritic reddish-grey biotite-augite-an- 

 desite 206) , with the ground almost completely glassy. 



(u) Dark grey fresh-looking gabbro-like diabase, coarsely ophitic, 

 much calcified (208). 



(?) Dark aphanitic diabase with ophitic structure but idiomorphic 

 pyroxene (216). 



(TV) Olivine basalt. Hyalopilitic ground with distant squarish 

 feldspars (275). 



(*) (211) A fine-grained light grey diabase. The distant small 

 phenocrysts lie in a hyalopilitic base. The augite is changed into a 

 granular mass, mainly calcite. 



PLOVER BAY 



At Plover Bay (plate v and fig. 10) on the shore of 

 Siberia the coast is mountainous, the bare cliffs rising 

 sheer from the sea. On either side of the bay the cliffs 

 seemed to be wholly made up of a light-colored granite. 

 Coasting along the shore to the east, and after passing 



the first deep valley 

 running up into the 

 land, we saw rock of 



oar, G ran,t* 



darker color, appar- 



FIG. IO. SKETCH OF THE SIBERIAN COAST. ' 



ently a darker gran- 



ite, and this continues for a long way east. The Eskimo 

 village in Plover Bay was placed as usual upon a long low 

 spit, and this is made up of coarse cobbles. 



No soil or plant growth interrupts the view of the shore 

 ledges. Only great streams of boulders occupy the steep 

 gorges, and under the influence of the frost are slowly 

 creeping downward. No sedimentary rocks or dikes 

 were seen, to break the monotony of the bare granite. 



The following rocks were found as boulders on the spit. 



Hornblende-biotite-tonalite (174). A rather coarse, light grey, 

 granitic rock, with small enclosures of fine grain and dark color. The 

 plagioclase is subporphyritic, fresh, abundant, and markedly zonal ; 

 the orthoclase flesh-colored, in smaller and rarer anhedra ; the biotite 



