J. D. Dunn — ^onfht >•<,,'<} l)',x<-} t < o't/r of Ijtl< Winnipeg. 431 



7. The slope of the lake-bottom prairie is northward, toward 

 Lake Winnipeg : and, from the 49th parallel, according to 

 Dawson, it is nearly six inches per mile ; the mean slope from 

 M'»>rhead in Minnesota, 150 miles south of the 49th parallel, is 

 little less than one foot per mile. 



The slope of the bordering plateau northward from Lake 

 Traverse to Luke Winnipeg, 8i5 miles, is about one foot per 

 mile; for 1,125-810 = 815. 



The slope of the bordering plateai 

 Big Stone Lake to Munkato (145 i 

 one foot per mile : for 1,125-975=150. 



8. The material of the lake-bottom, where examined by Mr. 

 Dawson, is mostly yellowish clayey earth or loess, containing 

 calcareous matter enough to effervesce freely with acids; the 

 upper portion is rarely so coarse as to be called sand, though 

 sometimes an arenaceous clayey material ; that of the border is 

 also somewhat arenaceous. The depth of this lake-bottom de- 

 ix'.-u is generally 40 feet or more over the central portions, bu 

 '_' thins toward the sides. This point is illustrated in the pla e 

 facing p. 248 in Dawson's Eeport. He represents the Icesa as 

 overlying stratified drift and bowlder clay. The surface of the 

 pi'.-nrie rises somewhat toward the sides'; but whether the de- 

 pression is more than would result from the drying (and conse- 

 'P'cnt contraction) of so much wet loam after the disappearance 

 of the lake, is not ascertained. It is rare to rind anything like 

 pebbly areas or pebbles over it. 



9. The outline of the lake-bottom prairie has the appearance 

 of being, so far as it extends, the outline of the great Winnipeg 

 Lake, and is so recognized by Warren, Dawson and others. 



10. The material of the bordering high plateau along both 

 the Red River portion and the Minnesota is coarse gravel and 

 sand ; much of it unstratified till, much, more or less stratified ; 

 and the upper surface is often pebbly or stonv, with occasional 

 bowlders. 



Roseau River, for 25 miles east of the western edge of the 



l"""-o ( , says I) ;iws <mi (p. 214), has cut deeply into the plateau 



formation so as to have hi-h bl.ilf sides: and' the sections show 



i»".U ofclav. .and and e ravel characterized bv'vur- 



: gravel, then t 



' typical one 



c,>[ " parted elav below, partly i 



™en sand, then the upper gravel. 



Lawson as examples of the constit 



"Unit Plateau of Eastern Manitoba and Northern Minneso 



He says of the great " High-level Plateau " that it is frequci 



"•regular in detail, covered with banks and ridges of sand <• 



