172 PHYSICAL GEOGRAPHY. 



(and for ten degrees of latitude all the rivers that originate 

 high on the prairie slope do so) form, on entering it, lake- 

 like expansions, which are studded with rocky islets, and 

 send long winding arms into all the neighbouring valleys. 

 These dilatations have little or no current, but they are 

 connected with each other by one or more straits, in 

 which the stream is turbulent and rapid, and the overfall 

 frequently great enough to produce a cascade. The tor- 

 tuous arms of such expansions often wind for many miles 

 through the country ; and the Indian, by making short 

 portages from one string of lakes to another, may travel 

 with his canoe in every direction, as far as the formation 

 extends. Sometimes a river forks in this rocky district, 

 and its branches running far apart, just as they would in 

 an alluvial delta, unite again, intercepting a considerable 

 tract of country of the prevailing character, that is, having 

 a predominance of water surface. Examples of this pecu- 

 liarity occur in the River Winipeg, which conveys the 

 waters of the Lake of the Woods to Lake Winipeg ; also 

 in the discharge of the latter sheet of water by Nelson 

 River and Play-Green Lake ; as well as in some of the 

 expansions of the Missinipi or Churchill River. Instances 

 also of lakes having more than one outlet are not rare in 

 this formation ; and now and then, though comparatively 

 very seldom, these outlets lead to distinct river systems. 



On the east side of Lake Winipeg the width of the 

 primitive belt is about two hundred geographical miles ; 

 and from the summit of an eminence which rises only a 

 few hundred feet above the general level, but yet is suffi- 

 ciently conspicuous to have obtained the distinctive ap- 

 pellation of " the Hill," thirty-six lakes may be counted. 

 In many localities, where the knolls are denuded of soil, 

 the surfaces of the rocks are evenly ground down, and are 

 sometimes smooth, polished, and striated. 



