KENDALL COUNTY. 137 



crab-apple, and other small trees. The soil of the timbered tracts is generally 

 light colored, sometimes sandy, or gravelly clay, often somewhat darkened in color 

 by an admixture of vegetable matter. On the prairies, the soil is mainly a 

 dark colored mould, but containing in some places a proportion of sand and 

 clay, especially near the borders of the streams and woods. The depth of this 

 soil varies from one to three feet. 



The deposits of the Drift epoch in this county, are in all respects a continu- 

 ation of the region adjoining on the north, and over the greater portion of it, 

 will probably average very nearly the same thickness, viz : from fifty to one 

 hundred feet. In the extreme southern portion of the county, there are dis- 

 tricts where these deposits are comparatively quite thin, but over by far the 

 greater part, they are seldom passed through by even the deepest wells. Ex- 

 cepting the Fox river, and the AuSable, none of the streams cut down to the 

 older rocks for any great part of their course, although they sometimes have 

 cut ravines sixty or eighty feet belew the general level of the country. The 

 beds of this age consist here, as elsewhere, of blue and yellow clays and hard- 

 pan, with occasional seams of quick-sand and gravel, and frequent boulders. 

 In two places in this county, I have noticed faint glacial striae on the exposed 

 surface of the underlying beds of the older rocks. One of these was on Big 

 Rock creek, near the southern half of section 1, township 37, range 6 east, 

 where the top of the uppermost strata of an exposure of Niagara limestone 

 was worn smooth and covered with faint scratches, running in the direction 

 south 60 east. The other locality, was in about the center of section 9, town- 

 ship 35, range 8, where a ledge of limestone of the Cincinnati group, appears in, 

 the bed of the AuSable creek. At this point the direction of the striae was 

 different, being about southwest. 



Along the Fox river, the materials of the Drift appear to have undergone a 

 sifting, and reasserting process, by the action of the river, the bluffs frequently 

 presenting sections of roughly stratified sand, coarse gravel and boulders, with 

 sometimes a bed containing fossil fresh water shells of existing species. A 

 good section of this modified Drift material, is afforded by the cutting down of 

 the bluff for the grade of a road near the center of section 4, township 36, 

 range 6, about ten and a-half miles south of Piano, where also a bed of shell 

 marl is to be seen, intercalated between very irregular layers of sand, gravel 

 and limestone boulders. 



Of the older geological formations, we have the following named in descend- 

 ing order: 



1. Coal Measures. 



2. Niagara Group. Buff, drab, and brown impure limestones, with frequent 

 nodules of chert. Aggregate thickness in this county, probably between fifty 

 and seventy feet. 



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