46 F. W. SARDESON SAINT ANTHONY FALLS 



to 20 feet deep by debris, including limestone blocks 1 to 25 feet square 

 and 1 to 6 feet thick. These blocks are almost exclusively from the lower 

 limestone. 



At the old Chevertown steamboat landing, between the ends of Pleasant 

 and Delaware streets, and on the boulevard, on the left side of the gorge, 

 another remnant of the fallscarp is preserved. The nearly right-angled 

 turn in the wall of the gorge preserves the edge of an upper rapids and 

 the fallscarp. These evidence that here also rapids descended 15 feet 

 over the upper limestone to the fall. The fall was 25 feet high, measured 

 from its crest at the top of the lower limestone. Below that scarp the 

 block-covered river bed, now a terrace, slopes from west to east and is 

 45 or 50 feet below the top of the limestone ledge and 25 feet above the 

 river at normal stage. The terrace runs some 300 yards to where it is 

 scarcely 15 feet above the river. A terrace which is from 10 to 5 feet 

 lower borders it on the south side. 



A sloping block-covered terrace runs under Washington Avenue bridge, 

 on the right side of the gorge, but the works of man have changed it too 

 much for the present purpose; also, on the left end of Tenth Avenue 

 bridge, the "east side flats" once presented doubtless a good record, but 

 it has been defaced by early quarrying and late grading. It can be seen, 

 however, that the limestone ledge had been eroded or glaciated here, so 

 that 5 feet of the upper limestone was lacking. The block-covered ter- 

 race began at the base of the lower limestone and sloped in some way 

 down to about 10 feet above the present level of the river in a fourth of 

 a mile. The height here was probably, of the upper rapids, 10 feet; 

 of the falls, 20 feet ; of the lower rapids, 20 feet ; total, 50 feet. 



This last terrace is so close below the position^" at which the falls stood 

 when they were seen by Father Hennepin in A. D. 1680 as to represent 

 practically the same stage. 



The Nicollet Island Eapids 



Before considering the Saint Anthony falls proper, which N". H. Win- 

 chell has described quite fully, I wish to call attention to what may be 

 called the Nicollet Island rapids, to which due attention has not been 

 paid heretofore. 



The limestone ledge which formed the crest of Saint Anthony falls, 

 and which is practically horizontal from Fort Snelling to the falls, shows 

 a rise upstream above the falls. "At the falls it amounts to about an 

 inch in 100 feet; it increases soon to 3 or 4 inches in 100 feet, and at 

 Central avenue it is about 5 feet in 100 feet." " 





" WInchell : Op. cit., p. 336 and plate Y. 

 " WInchell : Op. cit, p. 291. 



