tow.] GEOLOGICAL OBSERVATIONS. 23 D 



orthoclase, grey quartz and black mica, predominates ; with horn- 

 blende gneisses and schists, mica schists, crystalline limestones, and 

 an area of triclinie feldspar rocks. 



In the following pages a detailed statement of the rocks met with 

 in ascending the Betsiamites River and on the route to Lake Mistassini 

 and James Bay is given. 



The rocks are first seen on the Betsiamites, seven miles from its 

 mouth, and opposite the mouth of the Nepee River, where the hills of 

 the Laurentian range are entered. Between this point and the coast, 

 the river flows between sand-banks, with an elevation varying from 

 twenty to fifty feet. 



The first hundred feet of the exposure is dark-red, coarse-grained 

 gneiss, composed of red orthoclase, grey quartz and mica. Dip 

 S. 5(P W. at a high angle. Then, for liOO feet, light red, fine-* 

 grained gneiss, in which the quartz greatly predominates, banded with 

 coarse dark-red gneiss, composed chiefly of red orthoclase and grey 

 quartz, with a small quantity of dark-green decomposed hornblende 

 and mica. Also light-greyish gneiss, containing large proportions of 

 black mica and dark-green hornblende. One hundred yards beyond 

 the last, dark-red, coarse-grained gneiss, alternating with fine-grained 

 bands for fifty yards. 



Two and a-half miles farther up the river, an exposure of seventy- 

 fivo feet was seen, the rocks being fine-grained red gneiss, alternating 

 with bands of dark-grey hornblende and mica-schist. 



One mile bej-ond was seen coarse-grained red gneiss, containing large 

 crystals of pink orthoclase and black mica, with dark-grey quartz, 

 for one hundred yards. 



The next exposure occurred two miles further up the river, and 

 consisted of fine-grained dark-grey gneiss, composed of light-grey 

 orthoclase, black mica and a small quantity of quartz. Dip S. 60° E. 

 <60°. 



Then, two miles to coarse-grained red t;-neiss. some of which exhibits 

 no signs of bedding, and resembles the granite. The length of this 

 exposure is about two hundred yards. Two miles beyond is tine- 

 grained grey and red gneiss, the former predominating. Dip N. 60 D 

 W. < 50. 



No outcrops now occur on the river for twenty-one miles, when the 

 following fine exposure was seen. The section, in ascending order, is 

 as follows : — Thirty feet, dark-grey gneiss, containing masses of almost 

 pure pink orthoclase ; then thirty feet of coarse red gneiss, composed 

 chietl}- of red orthoclase ami grey quartz, resembling graphic granite. 

 Many dark-red garnets, as large as peas, are scattered through this 

 rock in bands. Above this is twenty-five feet of fine-grained grey 



