BOUND AEIES OF THE LAKE WINNIPEG BASIN. 241 



in a position the reverse of that produced by the meri- 

 dians and parallels distinguishing its boundary. 



The eastern rim of the basin of Lake Winnipeg is 

 formed by part of the Laurenticle range of mountains, 

 which consist of gneiss * interstratified in some localities 

 with bands of crystalline limestone, and much embossed by 

 domes of intrusive granite, syenite, and occasionally with 

 elevations of trap. The highest summit of the Laurentide 

 Mountains, as far as known in this part of their develop- 

 ment, does not exceed 1950 feet above the sea, or 1350 

 feet above Lake Superior. 



Striking off in a south-westerly direction from the 

 Savanne Lake, the Height of Land extends to Lake 

 Traverse and is composed of drift hills covering Lauren- 

 tian, Silurian, and Devonian rocks, with low granitic 

 ranges and exposures of trap. From the Dividing Eidge, 

 at the source of the Pigeon Eiver, south-westerly to 

 Vermilion Lake, the Height of Land Eidge is called by 

 the Indians Mis-sabe Wa-chu ; in its continuation to the 

 low water-shed between Eainy Eiver and the Mississippi 

 it has the name of Ish-ko-na-bi Wa-chu. Continued south- 

 westerly from the Falls of Pokegama, this ridge would 

 pass south of Leech Lake and strike the Eed Eiver of 

 the north near the Great Bend, at which point Dr. Owen 

 found Silurian rocks in 1848.f 



From this point on Eed Eiver the rim of the basin 

 assumes a north-westerly direction as far as the Elbow 

 of the South Branch of the Saskatchewan, along the de- 

 nuded flanks of the Grand Coteau de Missouri. From the 

 Elbow it turns south-west as far as Chief's Mountain Lake, 

 under the 114th meridian J, latitude 49°, where it meets 



* Under the general term " gneiss/' micaceous ; hornblendic, and chloritic 

 schists are included. 



t Geological Survey of Wisconsin, Iowa, and Minnesota. 



X Map of the Territory of the United States, by Lieutenant Gr. K. 

 VOL. II. R 



