GEOLOGY AND PALEONTOLOGY 17 



tallized, so that nearly all traces of sedimentary origin 

 are lost. 



No. 2 (29) shows a fine granular groundmass, largely of quartz but 

 with some feldspar, scattered through which, without parallelism, are 

 abundant scales of biotite. Magnetite in fine grains and opaque car- 

 bonaceous matter are also present. The quartz grains retain their 

 clastic character fairly distinctly. 



No. 3 (30) would be called from the thin section alone a granitoid 

 gneiss. It is a hypidiomorphic-granular aggregate of quartz grains 

 and sharply bounded, zoned crystals of plagioclase feldspar, the zones 

 giving extinctions corresponding to acid labradorite at the centre and 

 oligoclase at the boundaries. The feldspars are perfectly fresh, and in 

 the centre free from inclusions, but their outer zones are filled with 

 clastic grains which have been surrounded during the later growth of 

 the crystals. Many of them have the appearance of clastic grains sec- 

 ondarily enlarged during the recrystallization of the rock, but this is not 

 always evident. The interstices between the feldspars, which make 

 up perhaps half of the rock, are filled partly with the granular quartz, 

 partly with plates of biotite and grains of garnet and zoisite. No 

 parallel structure is visible in the slide. 



No. 4 (31) is similar to the last but appears more gneissoid, owing 

 to the parallelism of the biotite plates. It also has more quartz and 

 some muscovite. 



The field evidence is conclusive as to the sedimentary 

 origin of these rocks, and they offer a beautiful illustration 

 of the formation of gneiss from a feldspathic sandstone. 



The rocks of the last two localities probably belong to 

 the Vancouver Series described below, page 42. 



The celebrated garnet locality at the mouth of the Sti- 

 kine River is about ten miles north of Wrangell and is 

 probably in this same series. It was not visited, but it is 

 said to be very extensive. 



At Farragut Bay, Frederick Sound, the rock is a rather 

 uniform schistose serpentine, very thin-bedded, much 

 jointed, and in nearly vertical position. Quartz veins are 

 abundant. In thin section (13) this rock was found to be 

 a nearly pure fibrous serpentine, containing shattered frag- 



