EFFECT OF WIND ON THE LAKES. 



75 



posed by the great lakes of the Winnipeg Basin, is very 

 well seen at the Narrows near Manitobah Island, the 

 Dog's Head (Lake Winnipeg), Waterhen Eiver, and the 

 months of the Winnipeg and Eed Eivers. The currents 

 produced by the pressure of the wind changing the levels 

 of the lakes has probably exercised an important influence 

 in connecting different parts of the same lake basins. 



At the Narrows, Lake Manitobah, a northerly wind 

 will cause a strong current to flow through the straits into 

 the lower or southern half of the lake ; while a south 

 wind produces a corresponding effect in the northern 

 portion, and perceptibly increases the volume of water in 

 the Little Saskatchewan. At the Doefs Head the current 

 sometimes approaches the force of a rapid when the wind 

 blows from the north ; the great depth of Lake Winnipeg 

 at this point, which, I was assured by half-breeds and 

 Indians who fish there during the winter, exceeds one 

 hundred and twenty feet, is doubtless the result. 



At first sight it appears strange that the limestone cliffs 

 should not have been gradually broken away, and the 

 communication between the upper and lower portion of 

 Lake Winnipeg enlarged. But running water exercises 

 comparatively little effect in excavating a deep channel 

 through a rocky barrier, or in widening a water-course ; 

 ice, beyond all question, is the main instrument in abrad- 

 ing, denuding, and excavating. At the Dog's Head the 

 ice has little force on account of the proximity of islands, 

 either when acting with a thrust or bearing away masses 

 of rock frozen to its substance. By far the greater por- 

 tion of the ice formed on this part of the coast is so 

 protected by the islands as to melt before it can be 

 moved by winds with its rocky burdens to distant parts 

 of the lake. 



At Manitobah House I observed the water rise fully 



