XXX FISHES OF ILLINOIS 



This driftless area of northwestern Illinois contains about 

 1,030 square miles, and includes all of Jo Daviess county, two 

 thirds of Carroll county, and a part of Stephenson. The surface 

 is rolling and somewhat broken, with a general elevation vary- 

 ing between 700 and 1,000 feet, but rising in mounds and flat- 

 topped hills to the highest point in the state, an elevation known 

 as Charles Mound, in Jo Daviess county, 1,241 feet above the 

 level of the sea. The surface rock of this district is mainly 

 Galena-Plat teville, with Maquoketa shales and Niagara lime- 

 stone capping the higher hills. 



The principal streams of this region are Galena River to the 

 north and Apple and Plum rivers farther south. Many addi- 

 tional smaller streams run down from the hills and bluffs to 

 open directly into the Mississippi. 



GALENA RIVER 



Galena River, called Fever River on many maps, rises 

 chiefly in Lafaj^ette county, Wisconsin, which state contains 

 also nearly 135 of the 197 square miles of its drainage basin. 

 It runs with a rather rapid course through the hilly country 

 of western Jo Daviess county, often over a rocky bed, becoming 

 comparatively broad and sluggish as it crosses the Mississippi 

 bottoms west of the town of Galena to empty into the Missis- 

 sippi River. 



APPLE RIVER 



Apple River rises in Lafayette county, Wisconsin, and flows 

 southeast, then southwest and finally south, emptying into the 

 Mississippi in northern Carroll county, Illinois. It has a length 

 of about 45 miles and drains an area of 270 square miles. It 

 crosses the state-line at an elevation of about 950 feet, while its 

 mouth has an altitude of only 588 feet. In Jo Daviess county, 

 the upper channel of the river is narrow and the banks are 

 steep and 150 to 200 feet high. In the lower part, the valley 

 becomes broader and the banks recede until, in Carroll county, 

 the river enters the broad bottom-lands of the Mississippi. 



Except for the headwaters of the eastern branch, the entire 

 basin lies in the driftless area and therefore maintains its pre- 

 glacial course. It has, however, received a marked accession of 

 drainage because of the blocking of a preglacial tributary of the 

 Pecatonica. This diversion occurs just below Melville, and for 

 about 3 miles below this point the stream is in a gorge but little 

 wider than its bed. The small preglacial Apple River is then 



