138 Geology of Upper Illinois. 



Avidth and depth of the Des Plaines valley, and the immense 

 diluvial accumulations it contains below Juliet. 



Route of the Michigan and Illinois Canal. 



No internal improvement in the country will surpass in com- 

 mercial importance the canal which is to unite the waters of Lake 

 Michigan and Illinois river, since it will complete the navigable 

 route from the Gulf of St. Lawrence to the Gulf of Mexico, and 

 open a water communication, so to speak, from the Rocky moun- 

 tains to the Atlantic coast. The cost of the undertaking in some 

 degree keeps pace with its importance ; for although neither the 

 line of its extent, nor the amount of its lockage, is great, still the 

 difficulty which grows out of obtaining an adequate supply of 

 water for the summit division of the route, renders it the most 

 expensive work of the kind ever projected. It is indeed a fortu- 

 nate circumstance as affecting the certainty of its completion, 

 that the means for defraying its construction are already in the 

 possession of the State, the general government having given the 

 alternate sections of land for five miles on each side of the canal 

 to the State of Illinois, to be appropriated to this important under- 

 taking. 



Before speaking of the geological features of the country over 

 which the canal passes, a brief sketch of the route it takes, and 

 the nature of the difficulties it has to encounter, will be given, 

 inasmuch as such a notice will serve in some degree to explain 

 the topographical features of the region. 



The canal passes up the south branch of the Chicago river a 

 distance of four miles, thence over the level prairie in a direct 

 line eight miles, to the valley of the Des Plaines river, down the 

 valley of this stream, past the mouth of the Kankakee, to the 

 banks of the Illinois, whose border it pursues for a distance of 

 fourteen miles below Ottawa, where it enters the river. Its 

 length is one hundred and two miles ; and it is constructed with 

 a breadth of sixty feet at the water surface, and a depth of six 

 feet. The lockage is all downwards, and amounts to one hun- 

 dred and forty two feet. 



Before adopting the present route, an attempt was made to ob- 

 tain a supply of water for the summit division, from the Des 

 Plaines, the Calumet, and the Fox rivers ; but on running a level 



