DESCRIPTIOiSr OF THE AREAS 271 



Kaminis granite. 



Granite-gneiss. 



Hybrid granite roclis. 

 (Intrusive contact.) 

 Upper Missi series Arliose. 



Conglomerate. 

 ( Unconf ormitj^ ( ? ) . ) 

 Lower Missi series Slate. 



Graywacke. 



Quartzite. 



Conglomerate. 

 (Unconformity.) 



Cliff Lake granite-porphyry. 

 (Intrusive contact.) 



Kisseynew gneisses Sedimentary and igneous gneisses and 



schists. 



Amisk series Lavas, tuffs, agglomerates and derived 



schists. 



The oldest rocks of the region are volcanics, representing ancient sur- 

 face flows, with fragmental rocks of volcanic origin, ash beds, and ag- 

 glomerates. Some intrusive rocks closely related to the surface types 

 occur. The surface flows are now massive greenstones that locally retain 

 their original ellipsoidal and amygdaloidal structures. The massive 

 greenstones have suffered severe metamorphism and in thin section are 

 seen to consist of nothing but a felt of secondary minerals. In places 

 intense shearing and squeezing have developed marked schistosity. The 

 greenstone rocks are intruded by dikes of quartz-porphyry, a light gray, 

 fine-grained rock in places showing macroscopic quartz phenocrysts. A 

 complex of gneissic rocks occurring in the northern part of the area is 

 described under the term Kisseynew gneisses. Some of the gneisses are 

 of sedimentary origin, but there are also many sills and bosses of intru- 

 sive rocks. The sedimentary members are well bedded, light to dark 

 colored rocks, which consist of quartz, feldspar, biotite, and garnet. The 

 igneous rocks are granite-gneisses, some of them garnetiferous, probably 

 where masses of sediments have been absorbed. A great number of large 

 pegmatite dikes occur with this group. The sedimentary gneiss appears 

 to overlie the Amisk volcanics, but no trace of an unconformity was found 

 between the two, and the relation appears to be a gradual transition from 

 the dominantly igneous rocks of the Amisk group to the dominantly sedi- 

 mentary rocks of the Kisseynew gneisses. It is possible even that some of 

 the bands of the latter are merely altered representatives of the former. 

 The gneisses are therefore assumed to he merely the upper part of a great 

 formation of which the Amisk volcanics form the lower part. . 



