440 THE CANADIAN NATURALIST. [Vol. X. 



formation so as to have high bluff sides ; and the sections show 

 alternating beds of clay, sand and gravel characterised by "cur- 

 rent bedding;" one of them having stratified arenaceous clay 

 below, then coarse gravel, then sand, and then gravel as the top 

 beneath the soil ; another " typical one '' consisting of hard- 

 compjicted clay below, partly stratified, then a thin pebbly bed, 

 then sand, then the upper gravel. These are given by Mr, 

 Dawson as examples of the constitution of what he calls the 

 "Drift Plateau of Eastern Manitoba and Northern Minnesota." 

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

 irreo'ular in detail, covered with banks and ridses of sand and 

 gravel of the nature of " kanies," but on the whole, remarkably 

 uniform; on the 49th parallel it rises gently eastward toward 

 the Lake of the Woods, 90 feet in the 77 miles. On the upper 

 part of the Minnesota the deposits are largely the Glacial drift 

 (General Warren, and Professor Winchell), witli also portions 

 that are bedded. 



Conclusion. — Taking the accounts of the region from which 

 we have cited to be correct, we have the deduction forced upon 

 us that Winnipeg Lake did not lose its discharge into Hudson's 

 Bay and become the great lake with southward discharge, be- 

 cause of a barrier of ice or of any other kind. For if so, if 

 there had been no great change of slope over the region, the 

 shores of the great lake should be approximately horizontal, to 

 its outlet at Lake Traverse, and if horizontal, they would have a 

 height in the vicinity of the present Winnipeg of 260 feet above 

 the lake, supposing the waters just up to the Lake Traverse level, 

 and 300 feet if the water at this place of discharge was merely 

 40 feet deep. Instead of this condition, the observed shore line 

 hcfs nearly the present general slope of the surface ; and, further, 

 the slope of the lake-bottom prairie is not much different from 

 that of the bordering plateau on either side. 



We have thence the conclusion, since the present outline of 

 the lake-deposits or loesses whatever the present slope, was 

 approximately the shore-line and once horizontal, that there 

 has been a great change in tlic level of the laud, as General 

 Warren urged. The idea of a change in the position of the 

 earth's centre of gravity sufficient to change the slope of the 

 surface a foot a mile, or half a foot, cannot be reasonably enter- 

 tained. 



