ON THE LAKE SUPERIOR REGION 



95 



the central parts of the district, especially in the vicinity of Snowbank 

 Lake, but this locality was not visited by the party. 



In the Rainy Lake district the party observed the relations of the 

 several formations along one line of section at the east end of Shoal 

 Lake and at a number of other localities. The party is satisfied that 

 along the line of section most closely studied the relations are clear 

 and distinct. The Couchiching schists form the highest formation. 

 These are a series of micaceous schists graduating downward into 

 green hornblendic and chloritic schists, here mapped by Lawson as 

 Keewatin, which pass into a conglomerate known as the Shoal Lake 

 conglomerate. This conglomerate lies upon an area of green schists 

 and granites known as the Bad Vermilion granites. It holds numer- 

 ous large well-rolled fragments of the underlying rocks, and forms 

 the base of a sedimentary series. It is certain that in this line of sec- 

 tion the Couchiching is stratigraphically higher than the chloritic 

 schists and conglomerates mapped as Keewatin. On the south side 

 of Rat Root Bay there is also a great conglomerate belt, the dominant 

 fragments of which consist of green schist and greenstone, but which 

 also contain much granite. The party did not visit the main belts 

 colored by Lawson as Keewatin on the Rainy Lake map, consti- 

 tuting a large part of the northern' and central parts of Rainy Lake. 

 These, however, had been visited by Van Hise in a previous year, 

 and he regards these areas as largely similar to the green-schist 

 areas intruded by granite at Bad Vermilion Lake, where the schists 

 and granites are the source of the pebbles and bowlders of the 

 conglomerate. 



In the Lake of the Woods area one main section was made from 

 Falcon Island to Rat Portage, with various traverses to the east and 

 west of the line of section. The section was not altogether contin- 

 uous, but a number of representatives of each formation mapped by 

 Lawson were visited. We found Lawson's descriptions to be sub- 

 stantially correct. We were unable to find any belts of undoubted 

 sedimentary slate of considerable magnitude. At one or two local- 

 ities, subordinate belts of slate which appeared to be ordinary sedi- 

 ment, and one belt of black slate which is certainly sediment, are 

 found. In short, the materials which we could recognize as water- 

 deposited sediments are small in volume. Many of the slaty phases 



