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wholly without evidence and quite against the probabilities. Glacial 

 streams as a rule have the aggrading habit, and are not therefore 

 " withdrawn into the narrower limits of an eroded streambed," but on 

 the contrary, are constantly shifting their courses from one point to 

 another across their whole plain. Usually they subdivide into a com- 

 plex plexus of numerous shallow shifting branches. There is there- 

 fore no reason whatever to suppose that the present channel of the 

 Mississippi at Little Falls was in existence, even in its initial stages, 

 while the river remained truly a glacial stream. The fact that the 

 relic-bearing deposit is closely related to the present stream is evidence 

 that it was postglacial. The deposit that carries the relics supports 

 the same view, for it bears the characteristics of a postglacial rather 

 a glacial formation. On the evidence submitted, therefore, in the 

 paper the inference is rather imperative that the quartz chips were 

 buried at some stage when postglacial rather than glacial conditions 

 prevailed. To make this more clear, it may be worth while to sketch 

 the normal succession of events and to gather from these the normal 

 interpretation of the time and mode of burial of the quartz chips, 

 assuming, as everywhere throughout this review, the complete trust- 

 worthiness of the evidence given in the paper, especially that afforded 

 by its excellent photographic illustrations. 



i. During the time the glacial border lay across the sources of the 

 Mississippi and it was therefore truly a glacial stream, the normal 

 inference is that it had the aggrading habit because of its overburden 

 of glacial detritus ; that it took the form of a plexus of numerous 

 branchlets, and that it occupied, by the constant shifting of these, 

 the whole plain which it was engaged in building up. In the nature 

 of the case it should normally have no fixed channel nor any perma- 

 nent flood plain deposit, since its whole plain was periodically covered 

 by the channels of the branching and shifting streams. Its typical 

 deposits should have been clean, fresh, well-assorted stratified sands 

 and gravels. Any human relics left anywhere on the plain, even on 

 portions not at the time occupied by the stream, should have been 

 worked over and incorporated more or less deeply by scour-and-fill in 

 the clean, stratified gravels and sands. None such are reported. 



2. When the glacier had retired from the basin and no longer 

 overloaded the Mississippi with its detritus, a transition stage should 

 naturally have followed. During this the first work was to adjust the 

 stream to the conditions that immediately followed the glacial retreat. 

 It is to be presumed that the upper branches of the river were aggraded 



