XXV111 FISHES OF ILLINOIS 



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 1,000 square miles 

 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 gathering 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 following description rep- 

 resents the condition of this region before this work was so far 

 advanced as it is at present. 



Green River is about 93 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 descends rapidly, 25 feet in a mile, to the 

 sandy plain outside the moraine. There it soon enters the Inlet 

 swamps lying about 775 feet above tide. These swamps are 

 10 miles long and 2 to 5 miles wide. Through them the stream 

 has no definite channel but seems to be entirely lost. They are 

 mostly covered with a dense prairie grass among whose roots a 

 thin sheet of water is concealed in the wet seasons of the year. 

 Towards the center the water is deeper and patches of cattails 

 and rushes abound. From the western edge of this area, two 

 to three miles southeast of Lee Center, the surplus waters of the 

 swamps are gathered into a stream with a well-defined channel. 

 This leads westward for 15 miles to another wet area, the 

 Winnebago swamps, making a descent of about 3 feet per mile. 

 These swamps are very similar to the Inlet swamps but much 



