On the Wisconsin River Improvement 145' 



Wisconsin rivers, and is confirmed by their appearance. From 

 the foregoing we infer that the Wisconsin River was 

 in the trough of what was formerly a far mightier stream ; that 

 the ancient river was not on'y greater in volume, but cut deeper 

 into the bed through which it flowed ; that this ancient bed is 

 composed of the silurian or older rocks and is silted up many 

 feet deep. Such are a few of the facts which geology lays be- 

 fore the scientific engineer to guide him in making his plans for 

 water improvements. A knowledge of the old channels of 

 our rivers would have prevented the folly of making a canal 

 through the solid rock in order to avoid the falls of the Ohio 

 at Louisville, instead of digging through the drift of the old 

 channel of the river. Instead of probing with an iron rod 

 every inch of the bed of the Mississippi before we can deter- 

 mine the practical depth at which firm rock may be reached, 

 geology steps in and tells us it will be found at a depth of at 

 least 60 to 100 feet through the sand, with two remarkable ex- 

 ceptions at the rapids, one at Keokuk, the other at Hock 

 Island. Tiiese exceptions are readily accounted for, when we 

 know that the whole valley of the Mississippi was covered with 

 an extension of the Gulf since the glacial period as high up as 

 Savannah or Dubuque. That the silt brought in by the Des 

 Moines river in the one case, and the Iowa and Rock rivers in 

 the other, during this period, filled up entirely the valley cut 

 out by the great glacial river, and that when the land rose 

 again the Mississippi could not at these points regain its old 

 bed, so it had to cut a new one, which is not yet completedr 

 There is no doubt that Lake Erie had formerly an outlet past 

 Fort Wayne, Indiana, and down the Wabash valley, which in- 

 dicates the natural course for water communication between 

 the lake and the Ohio river. 



From these general remarks which will be recognized aa^ 

 germane to my subject, I will now turn to its special consid- 

 eration. The main features of the Wisconsin river are com- 

 mon to northwestern rivers. First, there is a high bluff ott 



