KANKAKEE AKD IROQUOIS COUNTIES. 237 



direction; but further consideration of the summit-levels of the Wabash has 

 shown that that stream would have given exit to the waters of Lake Erie at all 

 times when its elevation would have approached that of Lake Kankakee. 



The sands of these old river or estuary bottoms, are mostly quite pure silex, 

 and blown about by the winds. Judging from the material, it would seem 

 probable that at least the larger part of them originated from the disintegra- 

 tion of the sandstones of the base of the Coal Measures, which formerly covered 

 the larger part, if not the whole, of this county, together with an extensive 

 region on the upper Iroquois. They therefore have little fertility, except what 

 is due to the small quantity of river-silt deposited with them, and the debris 

 of the small amount of vegetation which has thus far grown upon them. They 

 are in some places entirely barren; in others, they are covered by a thin growth 

 of oaks and hickories. The present river bottoms are of course well covered 

 with a great variety of timber, being very fertile. 



The remainder of the county is rich, rolling prairie, covered with the char- 

 acteristic deep, black, mucky soil which produces such heavy growths of all 

 sorts of vegetables. This is based upon generally thin clay-beds of the " Loess," 

 and this upon the sands, gravels, and heavy boulder-clay of the Drift period, 

 which latter bed is, in at least one case, one hundred and sixty feet thick. In 

 a well sunk at Sheldon, the gravel above the boulder clay was found com- 

 pacted into a coarse sandstone. At a shaft and boring made in 1865, by Mr. 

 John Faulds, of Vermilion county, between Onarga and Oilman, the following 

 section of these surface deposits was obtained : 



FEET. 



Blue and red clay 98 



Sand and soft sediment 140 



Hard pan 10 



Hard stony clay 20 



Total 268 



At this depth limestone was encountered, and the boring stopped. This 

 may have been only a boulder, but was more probably a solid bed of the Niag- 

 ara group. A boring made in 1866, between Onarga and Spring creek, is said 

 to have reached a depth of four hundred feet without encountering any solid 

 rock. These and other borings in this region have indicated the existence of 

 an old channel running through the county, which is nowentirely filled with 

 the Drift deposits. Examinations in adjoining counties have shown that this 

 is the continuation of the valley now filled by Lake Michigan. Its course is 

 southward from the southern extremity of the lake, trending a little westwardly 

 (though still passing to the eastward of Momence, in Kankakee county), until 

 near the northern line of Iroquois, where it bends more strongly to the west- 

 ward, and passes on to the southwest corner of the county, with its eastern 



