6o 

 Miles and arK j there in the distance. Half a mile (o-8 



Kilometres. . v 



km.) west ol Harrington an area ot Algoman 

 biotite granite gneiss, which continues to Bear's 

 Pass, is entered. The country underlain by 

 this formation is generally more rugged than 

 the previous 20 miles (32 km). A short distance 

 west of milepost 207, Keewatin rocks are again 

 seen, but the contact with the granite gneiss is 

 not visible in the immediate vicinity of the rail- 

 way. 



207-3 m. Bear's Pass — Altitude 1,143 ft. (349 m.). 



333 • 8 km. From this point a trip five hours in 

 length is taken in boats around the shores of 

 the eastern arm of Rainy lake for the purpose 

 of examining the Coutchiching series, and ob- 

 serving its relations to the Keewatin and the 

 Algoman granite and syenites. 



THE COUTCHICHING SERIES ON RAINY LAKE 



General Description. 



The Rainy Lake area affords a typical example of the 

 rocky lake topography of the Pre-Cambrian shield. It is 

 part of that region investigated by Dr. Lawson in 1885- 

 1888 (5). The geology of this area was revised by the same 

 investigator in 191 1, certain important changes in correla- 

 tion being rendered possible by the improved accessibility 

 of the country and by the more advanced state of know- 

 ledge regarding Lake Superior geology in general. The 

 following descriptions and review of the geology are based 

 on the results of his recent work (191 1) (6). The geological 

 sequence of the rocks exposed is given below in descending 

 order: 



[Algoman 



I ■ — Irrwptive contact — 



Archaean | Hornblende gabbro (Keewatin ?) 



— Irrwptive contact — 



Keewatin 1 n , ■ 



r- j- u- u- Ontanan 



Loutchichmg J 



Coutchiching. — This group of rocks consists of mica 

 schists, feldspathic mica schists, and evenly-laminated, 



