ILLINOIS RIVER DRAINAGE BASIN. 507 



southern Will counties, though at a few points it approaches 50 feet. Out- 

 side of this, as previously described, there is a broad bottom, averaging 

 about 2 miles in width, which has a low bluff of till along- the north border, 

 rising 15 to 25 feet or more above it. But on the south there are sandy 

 ridges and knolls which seldom present a definite bluff line. 1 



Yellow River has a drainage area of about 700 square miles, of which 

 probably 500 square miles are within the limits of the Maxinkuckee 

 moraine of the Saginaw lobe and outside the region under discussion. 

 This portion on the Saginaw drift is widely branching and drains the 

 greater part of Marshall County, together with small parts of St. Joseph, 

 Elkhart, and Kosciusko counties. The portion west of the Maxinkuckee 

 moraine consists mainly of its immediate channel and the outlet of Twin 

 Lakes, its course being through a sand-covered district in which the 

 drainage is very imperfect. None of this watershed can be considered 

 well drained, although the headwater portion resembles the neighboring 

 portions of northern Indiana, which, like it, are under cultivation. The 

 soil, being a sandy loam, requires less perfect surface drainage than clay 

 soils, such as characterize the drift of the Illinois lobe. 



The Iroquois River has a watershed of about 2,000 square miles, 

 though much of this watershed is very imperfectly drained by it. Fully 

 800 square miles, or nearly one-half, lies in Indiana. At Watseka the 

 river receives its principal tributary — Sugar Creek. Below Watseka are 

 three noteworthy tributaries — Spring Creek, Langum Creek, and Beaver 

 Creek. In its passage through the Marseilles moraine in the lower 5 miles 

 of its course considerable descent is made, but elsewhere the stream is gen- 

 erally sluggish, and so are the tributaries. 



The west-flowing portion of the Iroquois drains a large sandy area in 

 Indiana south of the Iroquois moraine. It passes through that moraine 

 before reaching Watseka. Sugar Creek drains the outer face of the 

 Iroquois moraine in the portion southeast from Watseka, while Beaver 

 Creek furnishes the chief drainage for the outer face northwest from 

 Watseka. The basin in Iroquois County, south of the Marseilles moraine, 



1 Many data concerning the Kankakee Basin have been collected by Prof. L. E. Cooley and pre- 

 sented in a pnper contained in tbe Report of tbe Illinois State Board of Health, 1889. The writer is 

 indebted to this report for many of the statistics above presented, as well as for those of the Iroquois 

 and Yellow rivers, presented below. 



