CALHOUN COUNTY. 17 



sufficient thickness to be worked. On Mr. Wm. Love's place, the northwest 

 quarter of section 10, township 13, range 2 west, the gray concretionary lime- 

 stone which is found sixty-five feet above the coal at Williams's mine, outcrops 

 on the south side of the hill, about a quarter of a mile south of his dwelling ; 

 and probably the whole thickness of the measures, as developed in this county, 

 are to be found here, though there is no exposure of the beds below this lime- 

 stone in this vicinity. Coal has been found on the southeast quarter of section 

 26, on the northeast of 36, and on the northeast of 24, township 13, range 2 

 west, and the Coal Measures, probably, underlie fully one-half of the highlands 

 in township 13, ranges 1 and 2, in this county. 



Quaternary System. This system is represented in Calhoun county, by the 

 three most common divisions, Alluvium, Loess, and Drift. The alluvial de- 

 posits are mainly restricted to the bottom lands which skirt the Illinois and 

 Mississippi rivers on three sides of the county, except between Gap au Ores 

 and Milan, where the limestone bluffs jut boldly out to the river's edge. On 

 the eastern side of the county, from the mouth of the Illinois river to Monterey, 

 the bottom lands average nearly three miles in width, but above Monterey they 

 grow narrower, and range from a quarter of a mile to a mile and a half in 

 width. A considerable portion of these bottom lands are prairie, and are the 

 only natural prairie lands in the county. In the northwestern portion of the 

 county, there is a belt of bottom land, lying between Bay creek and the Mis- 

 sissippi river, which is about four miles wide at the county line, but grows 

 narrower to the mouth of Bay creek, where it is not more than half a mile in 

 width. The most of these bottom lands are dry enough for cultivation, and 

 are among the most productive and valuable lands in the county. 



Drift. The drift deposits in this county, probably nowhere exceed forty or 

 fifty feet in thickness, but they cover nearly all the uplands in the county, ex- 

 cept at some points along the summit of the bluffs, from whence they have 

 been removed by denudation. They consist of brown clays, some of which are 

 quite free from gravel, with some bluish beds containing gravel and boulders 

 of considerable size, but good exposures of these beds, except a few feet of the 

 upper portion, are seldom to be seen, as there are no railroad grades, or other 

 artificial cuts through this formation in this county. Where the yellow clays 

 of this deposit covers the surface, they form a heavy clay soil, rather hard to 

 work, but quite productive where there is a natural surface drainage. 



Loess. This formation consists of buff, brown, or ash colored, marly clays, 

 or sandy marls, usually quite distinctly stratified. It caps the river bluffs in 

 nearly all parts of the county, and is also frequently found filling the lateral 

 valleys by which the bluffs are intersected. Just below Grilead, the bluffs, as 

 well as the hills, for a mile or more back from the bluffs, are composed mainly 

 or entirely of Loess, which is here from fifty to seventy-five feet in thick- 

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