254 GEOLOGY OF ILLINOIS. 



The fire clay, No. 35, is, in some places, very largely developed, as on Tros- 

 per branch, about four miles northeast of Georgetown, where, below the open- 

 ing of the coal seam, on the northeast quarter of section 22, township 18 north, 

 range 11 west, I measured fifteen feet of clay in several alternating bands, 

 with from three to four feet of nodular, argillaceous limestone, and was not 

 certain that I had then reached the bottom of the bed, since the outcrop below 

 was not exposed. The clay is here much variegated with streaks, blotches 

 and beds of light blue, dark drab 3 dark brick-red, crimson and purplish tints, 

 the red portions furnishing the boys with an unlimited supply of " keel." The 

 accompanying nodular bands of limestone occasionally contain fragments of fos- 

 sils, but nothing characteristic. Possibly, some of the lower of these bands 

 may be the practical equivalent, of the fossiliferous limestones at the Slip-bank, 

 below the Horse Shoe of the Little Vermilion, which, however, lie some thirty 

 feet below the coal seam, the intervening beds being mainly fire clay and shales, 

 with some sand, and a few ironstones. The nodular limestones accompanying 

 the fire clay of this seam, at Pettys's ford of the Little Vermilion, about four 

 miles below Georgetown, have recently been found to contain considerable 

 numbers of small land snails of two species, one apparently identical with the 

 Pupa vetusta of the Nova Scotia Coal Measures, and the other, possibly a Zo- 

 nites, but smooth. 



The beds numbered 33 in the section, are exceedingly variable. The upper 

 layers, which are generally rather soft, contain, near and opposite Danville, 

 from one to five bands of a very hard, calcareous sandstone or silicious lime- 

 stone, varying from six to eighteen inches in thickness. Where exposed to 

 the weather, these are very hard and tough, but are softer below the surface. 

 Perhaps fifteen feet below the level of the floor of the coal, we find, at Leon- 

 ard's quarry, a mile or so below Danville, a thick bed of gray, highly ferrugi- 

 nous sandstone, which is in much favor as a building stone. The bed ig not 

 constant, running into sandy shale within a short distance. The lower beds 

 of this member of the series are all soft shales, of no practical value, and are 

 entirely destitute of fossils. For some distance below Danville, they form a 

 set of high bluffs, reaching seventy or eighty feet at least. 



After passing below Kyger's mill, near the mouth of Grape creek, the black 

 limestone and shales of Nos. 35 and 36, come above the water, and continue to 

 form the prominent feature of the river banks to below the State line. They 

 deserve notice only as indicating the level of coal No. 5, which is here wanting, 

 though it begins to make its appearance at White's mill, on the Little Ver- 

 milion, four miles above Newport, with a thickness of four inches, and contin- 

 ues along the outcrop southward, with a general thickness of ten or eleven 

 inches, nearly to Clinton, where it dips below the river level. At Hawley and 

 Hett's bank, on Norton's creek, about four miles above Clinton, it is locally 



