54 J 



GEOLOGICAL SURVEY OF CANADA. 



Snow and ice. 



Contact of 

 Huronian and 

 Laurentian 

 rocks. 



Enclosures in 

 the gneiss. 



is eight miles above the mouth, the river is here obstructed by three- 

 small boulder islands, with two similar islands below. 



The vegetation on the lower part of the river is almost arctic in 

 character, the only trees are stunted black spruce and a few tamaracks, 

 which grow on the terraces and in valleys and crevices between the 

 rocky hills. 



At the end of July many patches of snow and ice were seen on the 

 north slope of the gorges in the hills facing the river. At the first 

 portage below Pospiskagami Lake the junction between the coarse- 

 grained pink hornblcndic gneiss and a band of dark-green chloriticand 

 altered hornblendic rocks of Huronian age was seen. Near the line oi 

 contact the Laurentian gneiss is highly twisted and shattered, so that 

 fragments are seen embedded in the massive schistose, chloritic rock, 

 lying at right angles to the line of contact. Offshoots from the green 

 rock cut the gneiss and fill small cracks in it. The whole has the ap- 

 pearance of an igneous mass, which has broken through the gneiss 

 cracking and twisting it along the contact, and injecting itself into all 

 the small open fractures in the same. 



At the lower end of the portage are green chloritic or altered horn- 

 blendic rocks, highly schistose in structure, with light quartoze veins 

 generally running parallel to the bedding, but seen in places to cut 

 from one plane to another. Strike N. 10° W. 



The next exposure on the river is three-quarters of a mile below, 

 where the rock is composed of dark green altered hornblende, and a 

 dark tri clinic felspar, the whole resembling an altered diorite. Thirty 

 chains farther down stream exposures of grey Laurentian hornblende 

 orthoclase gneiss occur. A quarter of a mile beyond is a pink horn- 

 blende orthoclasc gneiss. A fine grained pink syenitic gneiss, enclos- 

 ing lenticular masses of dark hornblende was seen three-quarters of a 

 mile below the last exposure. Strike N. 20° W. 



At the portage, past the eight feet fall, the rock is a greyish-pink 

 hornblende orthoclase gneiss, highly contorted, with lenticular enclo- 

 sures of hornblende. 



For one mile along the upper part of the south side of the straight 

 stretch below the fall mentioned above, the rock is composed of gvey 

 felspar, and light green felspar. This rock breaks into slabs about two 

 feet thick, and dips S. 5° B. < 65°. 



Haifa mile below the last exposures is a highly contorted pink horn- 

 blende orthoclase gneiss, containing large quantities of fragmented 

 hornblende schist bands enclosed. Strike S. 35° W. 



At the fifteen feet chute the rock is similar to the last, and from here to 

 the mouth of the river all the exposures examined were made up of red 

 and grey hornblende orthoclase gneiss, the red predominating. 



