lviii FISHES OF ILLINOIS 



suspended silt, never clearing even at the lowest stages; and the 

 same is true of most of its tributary streams, especially those of the 

 lower Illinoisan glaciation. 



VERMILION RIVER 



Vermilion River drains an area of about 1,500 square miles in 

 Ford, Champaign, and Vermilion counties in Illinois, and a small 

 section of Fountain and Warren counties in Indiana. It rises only 

 a few miles from the source of a river of the same name which flows 

 northwest into the Illinois, to distinguish it from which it is often 

 called the Wabash-Vermilion or the Big Vermilion. Its course is 

 generally south and east, and it empties into the Wabash 10 miles 

 beyond the Indiana line. It has a length of about 81 miles, and a 

 fall of 320 feet. Its source is in the midst of the Bloomington 

 morainic system at an elevation of 800 feet. It flows thence south- 

 ward between two ridges, known as the Roberts and Melvin ridges, 

 and passes through the latter ridge, falling 70 feet in this distance of 

 17 A miles. At this point it receives a tributary of about the same 

 length from the west, which is known as the West branch of the 

 Middle Fork. This branch also rises at an elevation of 800 feet and 

 drains a sag or narrow plain between the Melvin ridge and the outer 

 moraine of the Bloomington system. From this union the stream 

 takes a southeastward course across the northeast corner of Cham- 

 paign county and into Vermilion county as far as Potomac, where it 

 turns abruptly southward and passes through the outer ridge of the 

 Bloomington moraine. A few miles farther south it receives its 

 larger western tributary, the Salt Fork, and the united stream then 

 flows east for about 6 miles to Danville, takes again a southeast 

 course, and follows this direction to its mouth. 



Salt Fork rises in western Champaign county at an altitude of 

 740 feet and flows south and then east for a distance of 50 miles. 

 It drains a plain in eastern Champaign and western Vermilion 

 counties, lying between the Bloomington and Champaign morainic 

 systems. 



North Fork rises in northern Vermilion county at an elevation 

 of 720 feet and flows southward for a distance of 37 miles, emptying 

 into the Vermilion at Danville. It drains only a small area among 

 the ridges of the Bloomington system. 



The entire drainage system of the Vermilion is independent of 

 preglacial lines, the drift over this region being so deep as to cover 

 completely the old rock divides. The river and its branches have 

 narrow valleys, and in the upper courses the banks are only from 10 



