MODIFICATION OF GREAT LAKES BY EARTH MOVEMENT. 361 



pass is about 8 feet above the mean level of Lake Michigan and 5 feet 

 above the highest level. Iu five or six hundred years (assuming the 

 estimated rate of tilting) high stages of the lake will reach the pass, 

 and the artificial discharge by canal will be supplemented by an inter- 

 mittent natural discharge. In one thousand years the discharge will 

 occur at ordinary lake stages, and after fifteen hundred years it will be 

 continuous. In about two thousand years the discharge from Lake 

 Michigan-Huron-Erie, which will then have substantially the same 

 level, will be equally divided between the western outlet at Chicago 

 and the eastern at Buffalo. In twenty-five hundred years the Niagara 

 River will have become an intermittent stream, and in three thousand 

 years all its water will have been diverted to the Chicago outlet — the 

 Illinois Eiver, the Mississippi River, and the Gulf of Mexico. 



