38 F. W. SARDESON SAINT ANTHONY FALLS 



similar in all respects to that of the Saint Anthony gorge, which indeed 

 is a continuation of the former. 



Beginning oe the Saint Anthony Gorge 



The erosion of Saint Anthony falls and gorge of the Mississippi began 

 near the present Tort Snelling at a time when the Glacial river Warren 

 (see figure 1) was at full volume. Winchell has estimated this begin- 

 ning to have been at a much later time. He says : 



"There is reason to believe tliat the volume of the Mississippi was reduced 

 to its modern stage before that of the Minnesota. When the Minnesota valley 

 was finally relieved of the drainage from lake Agassiz, the falls of Saint An- 

 thony may be said to have fairly entei-ed upon the uniform recession which 

 has been above considered.'" 



The Mississippi river undoubtedly did quite reduce to its modern stage 

 while the river Warren was yet at full volume, and it may be assumed 

 that such reduction in volume was affected by the final melting of the 

 glaciers from the head of the Mississippi, as Winchell has above said; 

 but that the Mississippi river was reduced to its modern stage before the 

 recession of the falls began above Fort Snelling is not fully evident, and 

 it is more than probable that the river Warren reduced to the Minnesota 

 Eiver stage long after the recession of the falls began. Besides the evi- 

 dence which I have already presented, a study of the terraces within the 

 gorge of the Mississippi will be given in a later paragraph to show when 

 the falls began. The mouth of the gorge will be now described for the 

 same purpose. 



The gorge of the Mississippi at Fort Snelling is remarkably narrow, 

 and its mouth appears as if truncated by the larger valley — the Minne- 

 sota (see plate 1). There is an abandoned channel or arm of the Gla- 

 cial Mississippi, or, perhaps more strictly, of the river Warren, a half 

 mile north and east of the mouth of the gorge. The land immediately 

 on the west side of the gorge is also not high. The mouth of the gorge 

 of the Mississippi is in fact far out in the original flat valley of the river 

 Warren, on the upper end of what was evidently once an island. 



From the position of the gorge's mouth it might be taken that the 

 Mississippi had originally "plunged" by the shortest route over the wall 

 of a preexisting Minnesota valley. Such a view appears to be the one 

 entertained by Winchell. However, the reason for the narrowness and 

 also for the particular location of the gorge's mouth may be explained 

 only by the existence of a buried narrow pre-Glacial valley which could 



» Winchell : Op. cit., p. 338. 



