66 44 33 17 Bituminous shale, with thin beds limestone... 57 19 Hard silaceous rock.... 20 Fine-grained sandstone... 65" As nearly as the limits of the formations can be made out from this section, I think that at least that portion between the base of the alluvium and drift, and the bituminous shale and limestone of this section, number seventeen, may be referred to the coal measures. The remainder is Devonian, with perhaps some of the upper beds of the lower carboniferous. The exact equivalent of the two beds of the coal passed through, may, perhaps, not be stated with certainty. The lower one, however, is probably No. 1, of the Illinois river section. The greatest depth reached in the boring was seven hundred and seventy-four feet, and the lowest rock was a gray porous limestone, the fragments of which, brought up by the instruments, were exactly similar in appearance to some of the upper limestones of the Niagara group, exposed in the northern part of the State, with which this formation may doubtless be properly identified. The coal seam which is worked in this immediate neighborhood is No. 4, as has already been stated. A good exposure of this coal may be seen near the track of the Toledo, Peoria and Warsaw Railroad, at a point of the bluff where the road enters the valley of Farm creek. It is here immediately overlaid by loess and drift, and is about four feet in thickness, the same as its average in other localities thereabouts. It is worked in various places, both in the river bluffs and for a mile or more up the valley of Farm creek, by horizontal drifts into the hill sides, some of which, in their various branches, are of considerable linear extent. The beds overlying the coal are not exposed to the surface at any point north of Farm creek, but the seam is generally found to have a roof of sandstone or sandy shale in the interior portions of the drift. Along the Illinois river bluffs, between Fon du Lac and Wesley City, there are several points where coal is now, or has been, worked, and there are a few exposures of the overlying sandstones in the bluffs near the main wagon road. South of Wesley City there are scarcely any exposures on the river face of the bluffs, but up the side ravines they are more numerous. In one of these ravines, some distance from the road, on the land of Mr. Davis, I observed the following succession of beds in a vertical exposure for about sixty rods along the sides of the bluffs: 1 Shale, passing downward into slate.........25 feet. It seems to me that the vein of coal observed here is still above both the seams which are worked in this region. The distance between this and the next vein below it, I should judge to be not more than forty or fifty feet. The limestone which always overlies the coal No. 6, is entirely wanting here, although, as may be seen by the section, a bed of limestone occurs below its under clay, and farther down the creek. Below the exposures from which the above sections were made up, numerous thin beds of limestone may be seen intercalated in the sandstone outcrops. These limestone bands seem to be somewhat fossiliferous, but no good specimens were obtained. In the northeastern part of section twentyfour, township twenty-five, range five, on a northern fork of Lick creek, I noticed a quarry in a ledge of soft, light gray and brown micaceous sandstone, generally thin bedded and shaly, but in some places with beds thick enough to answer for building purposes. The total vertical thickness of the exposure was less than twelve feet. Passing farther down the branch, in a general westerly and southerly direction, we find the hillsides along the banks strown thickly with fragments of similar sandstone, indicating the probable existence of the same beds but a short distance under the soil. a point on the immediate bank of the creek, near the centre of the section, I observed an exposure of about twenty feet of sandy and argillaceous shales, containing a thin seam of coaly matter, not over one or two inches in thickness at its best development, and from that down to nothing. About half a mile farther east, near At له the centre of the eastern line of the section, alongside of the road which crosses the creek at this place, and well up the bluffs, I observed the outcrop of a coal seam which had been worked to some slight extent, and which I take to be the upper workable vein of this region: No. 6 of the Illinois river section. The whole exposure of this point presented the following section: Farther to the eastward from this point, and higher in the bluffs, I observed limited exposures of reddish, shaly sandstones, or arenaceous shale, which seems from its position to overlie the uppermost beds of the above section. In the vicinity of Pekin there are but few natural exposures of the underlying rocks, but the lower coal is mined at several points in the neighborhood of the city. The coal is generally overlaid by black slate. Above the slate there is generally from twenty to forty or fifty feet of sandstone, or sandy shales, according to the locality of the shafts, on the edge of the bluffs, or farther up towards the rolling uplands. This sandstone may be seen in the bottom of the ditches at one or two points on the Fremont road, about a mile east of the city of Pekin, and in the vicinity of the principal coal mines. At Mr. Hawley's place, about five miles southeast of Pekin, a shaft was sunk, which passed through both the upper and lower coals, affording a section of the intermediate beds, which, as reported to me, were as follows: About two miles east of Mr. Hawley's place, in the southwest quarter of section twenty, township twenty-four, range four, on a branch called Lost creek, there is said to be another exposure of brownish sandstone, of very limited extent. I failed to find the locality myself, but if sandstone occurs here, it may be that overlying the lower coal, or possibly the higher bed not represented in the above section. In the central and eastern part of Tazewell county there are few localities where borings, etc., have been made, but satisfactory records of the variation of the strata could not in all cases be obtained. At Rapp's Mills, near the centre of the north line of section twenty, township twenty-four, range four, a shaft was sunk to the depth of eighty-five feet, but, as it was reported to me, it struck limestone at that depth. If this be the case, it is very possibly the limestone overlying the upper coal, but without more reliable data it is impossible to speak with certainty. The shaft was abandoned before completion, on account of the difficulty in keeping it free from water. At Delevan, in the southeastern portion of the county, a boring was made, which was reported to have passed through sixty feet of sandstone, and below that seventy-five feet more of arenaceous and argillaceous clay shales. No coal was reported in this boring. In In Mason county there are no natural exposures of the older rocks, and as far as I can ascertain, no good artificial sections afforded in shafts, wells or borings. Passing eastward, however, into Logan county, we find along Salt creek, some distance above Middletown, a few tumbling masses of bluish limestones, which have evidently come out of the bluffs, but no good exposures. southeast quarter of section thirteen, township nineteen, range four, a boring was made in the side of the bluffs by Messrs. Boyd, Paisley & Co., of Lincoln, which passed 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 stated also 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 thick 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 exactness the place in the series of this seam of coal, though it is undoubtedly among the measures of the upper beds. At Rankin's mill, about two miles farther up the stream, in the northwest quarter of section 7, township 19, range 3, the creek flows over a bed of limestone, which is also quarried at one or two places on the southern bank. The rock is a light gray or bluish gray, irregular bedded limestone, and contains a few of the common coal measure fossils, of which Spiriffer, Cameratus, S. Lineatus, 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, 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 is continued by a 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 this district. There remain, however, various shafts, borings, &c., which, over the larger portion of the territory, afford us the only means whatever of ascertaining the character and the 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 afforded the following section after passing through about seventy feet of soil and drift: I Light blue arenaceous shale..... 2 Hard blue limestone, containing corals..... 4 Coal...... 5 Fire-clay... 6 Arenaceous shale...... 6 feet. 3 66 O 10 inches. I 6 66 6 feet. The black slate which had been taken from the shafts was too much decomposed at the time of my visit for me to obtain from it any very well preserved fossils, although among the rubbish I observed various indistinguishable fragments of what had apparently |