PAPERS OX GEOLOGY AND GEOGRAPHY 375 



streams of tlie region necessitated concrete aqueducts 

 through which the canal was carried above them. The 

 earth material encountered was mainly morainal. No 

 rock excavation was necessary except near the upper 

 entrance to the canal around the rapids in the lower 

 Eock River. The position of the C. R. I. & P. railroad 

 necessitated in many cases canal building at a higher 

 level than originally planned, and the circumventing 

 of the rapids near the mouth of the Rock River 

 introduced the use of high embankments to maintain 

 canal level with regard to flood conditions and to slack 

 water. The swampy condition of summit level, a region 

 overlying a former peat bog interspersed with pockets 

 of quicksand, introduced the lining of the canal with 

 planks and clay in order to maintain a channel. The 

 construction of the feeder had as its most serious prob- 

 lem the location of the dam in the Rock River from above 

 which the canal water could be taken. Consideration of 

 the eifect upon previous power constructions in the Rock 

 River resulted in the locating of the dam at Sterling, 

 and the carrying of the canal feeder southward along 

 the divide. 



Although authorized in 1890, actual construction of 

 the canal did not begin until July, 1892, with the building 

 of the section around the rapids in the Rock River near 

 the town of Milan. This section, four and one-half miles 

 in length, was opened to tralBfic on April 17, 1895 at a 

 cost of #547,229.93. A dam in the river above the rapids 

 afforded slack water transportation from the eastern end 

 of the Milan section of the canal to Colona, where the 

 main line of the canal joined the Rock River. "Water 

 from the Rock River was turned into the feeder in the 

 fall of 1907, and on Xovember 15th of that year, the 

 first vessel passed from the Illinois River through the 

 entire length of the canal to the Mississippi. The actual 

 cost of construction was 17,319,563.39, a figure almost 

 double the early estimates. 



"Immediately upon the completion of the canal", said 

 its chief engineer in 1908, ' ' people began to look for the 

 effects its promoters had assured would result from its 



