THE TOPOGRAPHY AND HYDROGRAPHY OF ILLINOIS XXV 



bottoms, which in some places spread out to a width of 3 miles. Its 

 earthen banks are low and rounded, and covered with heavy tim- 

 ber. 



KISHWAl'KEE RIVER 



Kishwaukee River is formed by two branches which unite about 

 12 miles above its mouth. The northern branch rises in the Wis- 

 consin moraine in central McHenry county, and the southern in the 

 same moraine in southern DeKalb county. Each of these branches 

 is about SO miles long, the whole system draining about 1,266 square 

 miles. The lower part of the river lies in drift of the Iowan age, while 

 the upper parts are in that of the Wisconsin age. The northern 

 branch falls about 25 feet in the first 3 miles, and below this the 

 descent averages two and a half to three feet per mile. The south- 

 ern branch is a little swifter, with an average fall of about 4 feet per 

 mile. The waters of this river are very clear compared with those 

 of the Pecatonica. The banks of the river are not precipitous, al- 

 though rising 40 to 50 feet high at some points. The entire river 

 valley is low, undulating, semi-prairie country, more or less wooded. 



GREEN RIVER 



Green River and its basin are quite distinct in their character 

 from the other tributaries of Rock River and their basins. The 

 drainage basin of Green River covers about 1,131 square miles (10th 

 Census) , all of which lies on a lake-plain of sand and gravel outwash 

 from the Wisconsin glacier, the river following for most of its course 

 the northern boundary line of the Wisconsin terminal moraine. The 

 surface soil consists of peat, underlaid by sand and gravel. Through 

 this the streams have found difficulty in making their way, unable to 

 cut definite channels through it down to base level. The country 

 consequently remains very imperfectly drained, and the waters gath- 

 ering between the sand-hills have formed great peat marshes and 

 bogs. Much is being done in late years, however, toward reclaiming 

 these swamps by means of extensive tiling and ditching. The fol- 

 lowing description represents the condition of this region before this 

 work was so far advanced as it is at present. 



Green River is about 100 miles long, extending from eastern Lee 

 county southwest across the corner of Bureau county and then west 

 through Henry county to its northwest corner, there emptying into 

 Rock River. Its headwaters are found in the elevated moraine 

 forming the border of the Wisconsin drift in southeastern Lee 

 county, and stand 950 to 1,000 feet above tide. The eastern stream 



