THE CENTRAL REGION OF NORTH AMERICA. 



605 



height, according to Sir J. Rich- 

 ardson, is 1566 feet. Near its 

 western extremity it would ap- 

 pear (according to Dr. Hector's 

 observations) to be about 2400 

 feet. It is probable that this 

 watershed is lower than either 

 of these measurements in the 

 intervening region. 



Between the two transverse 

 watersheds thus defined, the three 

 prairie steppes or plateaus of dif- 

 ferent elevation now to be de- 

 scribed are embraced. 



The whole of the region slopes 

 gradually eastward from the most 

 elevated plains at the base of the 

 Rocky Mountains to the lowest, 

 at the foot of the Laurentian pla- 

 teau to the east. The inclination 

 becomes more abrupt on approach- 

 ing the mountains, but not so 

 much as to attract special atten- 

 tion ; but along two Hues which 

 are in a general way parallel and 

 hold a north-west and south-east 

 course across the plains, a very 

 marked step-like rise occurs. 

 These escarpments form the east- 

 ern boundaries of the two higher 

 prairie plateaus. The lowest and 

 most eastern prairie-level is that 

 which includes the valley of the 

 Red River in its southern portion, 

 and northwards embraces Lake 

 Winnipeg and associated lakes 

 and the flat land surrounding 

 them. Its average altitude may 

 be estimated at about 800 feet ; 

 its area at 55,600 square miles, 

 of which the great system of 

 lakes in its northern part occupies 

 13,900 miles ; its average width 

 is over 100 miles ; its eastern 

 boundary is in part conterminous 

 with the shore of Lake Winnipeg 

 and the Laurentian axis, in part 

 formed by the great drift pla- 

 teau south of the Lake of the 

 Woods. Its western limit is 



