12 DRIFT DEPOSITS OF ILLINOIS. 



mence; the exact location of its eastern bank is unknown. 

 From this point the course of the channel is not certain; but 

 it proba.bly keeps near the State line until it nearly or quite 

 reaches the valley of the Iroquois, then runs westerly to the 

 valley of Spring creek, having a depth of one hundred and 

 sixty feet near Sheldon (as reported by H. S. Wing, Esq., of 

 Kankakee City,) and then turns south with a depth of two 

 hundred and sixty-eight feet between Onarga and Oilman, of 

 'over four hundred feet' between Onarga and Spring Creek Sta- 

 tion' and of 'over three hundred feet' between Paxton and Ean- 

 toul, as reported by John Faulds, Esq., of Catlin, Vermilion 

 county." 



"As the western bank w r as found at Chatsworth, Livingston 

 county, with its top eighty-eight feet and its bottom two hund- 

 red feet below the surface, thus giving a width of fifteen miles 

 or more, it is evident that the softer materials of the Devon- 

 ian, Sub-carboniferous, and Coal Measure shales and sandstones 

 have afforded less resistance to the denuding agent than the 

 solid Silurian limestones which confined it to less than seven 

 miles at Momence. Champaign and Urbana, in Champaign 

 county, are located over this old channel, and from one hund- 

 red and seventy-five to two hundred and twenty-five feet above 

 its floor, but are probably near its eastern border. Here and 

 at Chatsworth we find, among the drift-beds, a single layer of 

 old mucky soil, with leaves and trunks of trees. At Blooming- 

 ton, in McLean county, the channel is two hundred and fifty 

 feet deep, and the beds which fill it include two beds of old soil, 

 which I am inclined to accept as indications that this point is 

 near the middle of the old valley, or at least near its principal 

 channel." 



Dr. Bannister, in his report on the northwestern counties of 

 the State, gives no artificial sections of the drift, but he gives 

 the following as an approximate section of this deposit in the 

 bluffs of Lake Michigan, near Lake Forest: 



Ft, In. 



Clay 10 to 14 



Hand and clay intermingled 9 to 12 



Clay 1 to 1 C 



Sand 1 



Clay 50 



Maximum 78 6 



