260 DEPARTMENT OF THE INTERIOR 



2 GEORGE V., A. 1912 



Bayonne batholith. Peripheral schistosity and cleavage and a very intense 

 degree of recrystal'lization have been developed about that batholith. 



Belts F and G are also much disturbed and altered in the vicinity of the 

 Bykert granite batholith in the southeastern corner of the area. The eastern 

 limit of belt G occurs at a master fault, along which quartzites referred to the 

 Kitchener formation have been dropped down into contact with the pre-Oam- 

 brian schists. 



Petrography of Belt A.- — South of Summit creek the Irene conglomerate 

 directly overlies belt A. This is a heterogeneous group of rocks, including 

 biotite, chlorite, and sericite schists; sheared, compact quartzites; and dolo- 

 mites. The micaceous schists occupy most of the belt; sericitic quartzites are 

 next most abundant; the dolomites occur as thin bands intercalated in schist 

 and quartzite. 



The schists vary in colour from light to dark greenish gray, according to 

 the nature and abundance of the essential micaceous mineral, sericite, biotite, 

 or chlorite. They are often interrupted by veinlets of quartz and of dolomite 

 lying in the schistosity planes. In certain phases crystals of dolomite occur 

 in individuals or groups disseminated through the schist. Bock types transi- 

 tional between the true schists and impure dolomite are found. On the west 

 fide of the trail at Copper Camp the dark phyllitic schist is abundantly charged 

 with single crystals and small clumps of a light brown ferruginous carbonate 

 which is probably ankerite. The rock has, in consequence, a pseudo-porphy- 

 ritic appearance. 



The quartzitic bands sometimes run over a hundred feet in thickness. 

 They are always sheared, with an abundant development of sericite in the 

 shearing planes. At several localities the quartzites, like the schists, are 

 magnesian to some extent. They thus pass over into the dolomites which have 

 the habit of compact, more or less silicious, marbles. On fresh fractures the 

 dolomites range in colour from white to a delicate pinkish-brown, weathering 

 to a light though decided buff tint. The exposures of the dolomites in belt A 

 are very poor but it appears that no one bed measures much over fifty feet in 

 thickness. 



Throughout most of the belt the strike of both bedding and schistosity 

 averages a few degrees west of north and seems to cut the plane of uncon- 

 formity with the Summit series at angles varying from 10° to 25°. The dip is 

 generally nearly vertical but angles of 75° to 80° to the eastward are not 

 uncommon. About one mile south of the Dewdney trail the belt is broken by 

 a strong transverse fault along which, as shown in the map, the block to the 

 south has been displaced westward with respect to the block on the north. 

 Within the northern block the belt rapidly narrows down as if there it had 

 been cut away during the erosion preceding the deposition of the Irene con- 

 glomerate. In this short tongue of belt A the strike averages about N. 30° E. ; 

 the dip about 75° northwest. 



Large quartz veins, usually lying in the planes of schistosity are common 

 in the schists. One of these veins, from 15 to 20 feet in thickness, and well 



