WOODFORD COUNTY. 335 



first settlement of the county, and the process of denudation is continually 

 going on. 



The principal varieties of timber noticed on the level portions of the tim- 

 bered lands were white, red, black and laurel oak, and shell-bark and bitternut 

 hickory, and along the slopes of the bluffs and in the valleys of the small 

 streams, there are, in addition to those above mentioned, sugar and white 

 maple, box elder, black walnut, butternut, white and red elm, mulberry, wild 

 cherry, sycamore, cottonwood, white and blue ash, hackberry, and red-bud, 

 with an undergrowth of sumac and hazel. 



On the bottoms of the Illinois river, we find white elm, willow, buckeye, 

 black ash, cottonwood, and in the dryer portions the common varieties of oak 

 and hickory, sycamore, and a few other kinds. 



/ 



Surface Geology. 



This comprises the usual subdivisions of the Quaternary, Alluvium, Loess 

 and Drift. The most extensive alluvial deposit in this county is on the west- 

 ern border, along the Illinois river. It extends from the north line of the 

 county to Spring Bay, with an average width of about two miles. South of 

 Partridge creek, it becomes narrower, and gradually decreases in width, till at 

 Spring Bay the bluff comes nearly to the river, leaving but a very narrow strip 

 of bottom land. Along the river much of this land is wet, and only valuable, at 

 present, for its timber, as it is subject to overflow at every considerable rise of 

 the river. Occasionally there are low ridges that run nearly to the river, and 

 here the land, together with that nearer the bluff, is valuable. The soil is a 

 black, peaty loam, somewhat mixed with the sediment deposited at high water, 

 and occasionally with fine gravel and sand. It is very fertile and produces 

 large crops when sufficiently raised above the river. 



Along the valleys of the small water courses, there are generally some allu- 

 vial dsposits, but they are quite limited in extent, seldom exceeding a few rods 

 in width. The soil is a dark colored loam, intermingled with sand and gravel. 



Loess. In township 28, range 2 west, on Richland creek, a deposit of sandy 

 clay was found which contained fresh water shells, probably of existing spe- 

 cies, but this bed appeared to underlie the yellow clays of the Drift, and will 

 be noticed under that head. It is probable that the Loess caps the bluff of the 

 Illinois, at least in places, but no point was observed where it could be identi- 

 fied with certainty. 



Drift. The entire surface of the uplands of the county are covered by ac- 

 cumulations of this age, which attain a thickness of from fifty to one hundred 

 and twenty-five feet. These deposits comprise a series of yellow, brown and 



