BEGINNING 01? THE GORGE 37 



control the Mississippi's course at that place. The buried valley is evi- 

 dent at Mendota, opposite the mouth of the gorge, on the south side of 

 the valley of the river Warren. An embayment lies in the valley's wall at 

 Mendota. The back of the embayment is drift-covered or drift-filled, 

 while the limestones and sandstone end abruptly on either side, as in case 

 of a cross-cut buried valley. This buried valley may be a small branch 

 from the buried pre-Glacial Minnesota lying south of Mendota, and it 

 may have headed possibly a mile northwest of the present mouth of the 

 gorge of the Mississippi. Such a valley transverse to the river Warren 

 could have influenced that river's abandonment of the left channel and 

 at the same time drawn the Mississippi into its present course. 



In cutting the deeper channel, as before described, the river Warren 

 followed obviously the right side of its older high and wide valley (see 

 figure 2). The abandonment of the channel on the left side of the island 

 opposite Fort Snelling is accounted for in a general way as due to the 

 drawing of the stream to the deeper channel as it was made. In partic- 

 ular, however, one circumstance requires explanation, namely, the aban- 

 doned left channel beds upon the limestone ledge, as low as the crest of 

 Saint Anthony falls would be at any stage. From the upper end this 

 channel appears to be a course of the Mississippi abandoned just prior to 

 the recession of Saint Anthony falls. At the lower end there is no chan- 

 nel nor alluvial beds and no evidence of a cataract where the Mississippi 

 could have plunged from this channel into the deeper valley of the river 

 Warren. The only explanation for that circumstance is that the river 

 Warren for about a mile below the present Fort Snelling and the Missis- 

 sippi for about a mile above that point may have settled in their valleys 

 simultaneously and quickly as the oblique pre-Glacial valley at Mendota 

 was encountered by a receding cataract of the former river, which would 

 be first at a point about opposite the lower end of the left channel. Into 

 this drift-filled and easily eroded course the rivers Warren and Missis- 

 sippi could quickly settle, causing the abandonment of the left channel 

 at once. 



There appears therefore to have been no Saint Anthony falls at Fort 

 Snelling, but rather the river settled into a narrow, easily eroded pre- 

 Glacial valley at that place. The time of this event was while the river 

 Warren had not yet ciit its valley to near completion.- 



Early Stages of the Falls 



Distinct evidence that there were falls or strong rapids on the Missis- 

 sippi aliove the mouth of the gorge is found first about a mile upstream, 



