184 GEOLOGY OF ILLINOIS. 







In Mason county there are no natural exposures of the older rocks, and, as 

 far as I could ascertain, no good artificial sections are afforded in shafts, wells, 

 borings, etc. Passing eastward, however, into Logan county, we find along 

 Salt creek, some distance above Middletown, a few tumbling masses of bluish 

 limestone, which have evidently come out of the bluffs, but no good exposures- 

 In the southeast quarter of section 13, township 19, range 4, a boring was 

 made in the side of the bluff, by Messrs. Boyd, Paisley & Co., of Lincoln, which 

 passed through one hundred and thirty feet of alternating beds of limestone, 

 and arenaceous, and argillaceous shales, passing through the Drift and surface 

 deposits at the depth of only fifteen feet. A seam of coal was also stated to 

 have been met with near the bottom of the boring, but its thickness could not 

 be satisfactorily ascertained. I also heard it stated that a seam of coal about 

 two feet in thickness, had been worked by the early settlers of the county 

 in this vicinity, and afterwards abandoned on account of its poor quality. 

 No traces of the outcrop, or the old workings, are now visible, and I am not 

 able to state with any degree of exactneas, the place in the series of this seam 

 of coal, though it is undoubtedly among the upper beds of the Coal Measures. 



At Rankin's mill, about two miles farther up stream, in the northwest quar- 

 ter of section 7, township 19, range 3, the creek flows over a bed of limetone, 

 which is also quarried at one or two places on the southern bank. The rock is 

 a light gray, or bluish-gray, irregjular bedded limestone, and contains a few of 

 the common Coal Measure fossils, of which Spirifer cameratus, S. lineatusi 

 Athyris subtilita, and a few others only were collected. Its thickness here, as 

 ascertained by means of a well dug in one of the quarries, was eleven feet j 

 and underneath it was found four feet of black slate, underlaid by seventeen 

 feet of fire clay, and then six feet of limestone. The hole was continued by 

 boring to a depth of eighty feet from the surface, at which depth a seam of coal 

 was struck, the thickness of which I was unable to ascertain. This, or a similar 

 bed of limestone, outcrops on Lake Fork of Salt creek, in section 23, township 

 19, range 8, in a ledge about three feet high, which has been quarried to a slight 

 extent at one point, near the center of the section. 



The above comprises all the natural exposures within the limits of the district. 

 There remain, however, various shafts, borings, etc., which, over the larger por- 

 tion of the territory, aflbrd us the only means whatever of ascertaining the 

 character and thickness of the underlying beds. Of these, with one or two 

 exceptions only, the shafts alone furnish sufficiently reliable sections of the 

 strata, and as yet but two or three have been sunk. At Lincoln, the shaft 



NOTE. Since this report was written, the shaft at Lincoln has been completed down to the 

 coal, but we have not been able to get any response to our application for a copy of their jour- 

 nal, and consequently cannot state definitely the thickness of the coal seam, or its depth 

 below the surface. A. H. w. 



