60 J GEOLOGICAL SURVEY OF CANADA. 



On the portage past the fifty-five feet fall, is a fine-grained pink mica- 

 ceous gneiss, penetrated by large veins of pink orthoclase and quartz. 



On the hill top, on the portage from the river valley, the rock is 

 chiefly a dark red S3 r enitic granite, holding small dark red garnets. 

 Along with it are thin bands of highly contorted fine-grained pink 

 Dykes. micaceous gneiss. An immense dyke of dark green diorite, made up 



of moderately large crystals of dark green hornblende, and dark blue 

 plagioclase. This dyke is over two hundred yards wide, and was seen 

 cutting the hills on the opposite side of the river valley several miles 

 away. Its direction is S. 35° E. 



Another similar dyke, sixty feet wide, cuts the rocks in a N. 25° E. 

 direction at the small lake half a mile north of the other, and may be 

 an otfshoot of the larger dyke. 



On the portages between the small lakes to the height of land are 

 exposures of pink mica-gneiss, associated with a dark-red variety, 

 Gneiss. made up principally of dark-red orthoclase, with some quartz and 



small quantities of mica and a greenish hornblende. These rocks are 

 often very much contorted ; their general strike is S. 80° W. At the 

 height of land portage are similar exposures, the hornblende showing 

 signs of decomposition. Strike N. 63° W. 



The rocks examined along the lakes and portages of the next tri- 

 butary were found to contain more hornblende, with little or no mica, 

 and in places to enclose hornblendic segregations. General strike 

 1ST. 57° W. 



On crossing the height of land to the lakes draining into Clearwater 

 River, the rocks contain larger quantities of hornblende, with more 

 frequent hornblendic enclosures and schist bands. 



On the portage from the small branch to Clearwater River are two 

 dykes. The first one is on the hill, a short distance from the branch ; 

 it is olive-green in color, very fine-grained and compact in structure, 

 and varies in width from five to fifty feet, with a direction of N. 70° E. 

 The second dyke, near the Clearwater River, is coarser in texture, and 

 composed of light-green plagioclase and dark-green hornblende ; it is 

 sixty feet wide, and runs N. 75° W. The rock cut by these dykes is a 

 coarse-grained, pink hornblende-gneiss, containing broken bands of 

 hornblende-schist, Strike N. 55° W. 



At the head of the island, a short distance from the portage to Clear- 

 water River, another diorite dyke, thirty feet wide, was seen runinng 

 N. 85° W. 



All along the Clearwater River to the lake the rock exposures were 

 found to be composed of a pink hornblende-gneiss, often granitic in 

 structure, associated with a greater or less number of bands of dark 

 hornblende-schist, and usually enclosing fragments or segregations of 

 hornblende-rock. The average strike is north-west. 



Diorite dykes. 



