ELEVATION AND DEPRESSION OF THE COAL MEASURES.
The common level of the Illinois coal measures is above the Mississippi at St. Louis, which is 381 feet above sea-level, and the total thickness of the coal-strata is 900 feet; add to this the thickness of the Tertiary and drift, which is 350 feet, and we find the elevation of the highest points in Illinois within the coal-field to be 1631 feet above the Atlantic or the Gulf of Mexico, or the elevation of the coal measures to be 1281 feet above tide. The highest point on the Illinois Central Railroad is 1095 feet above the sea-level.
The Illinois or the Great Central coal-field in Kentucky and Illinois is the lowest point of the Mississippi Valley where coal is found; the deepest basins, however, exist in the Alleghany coal-field,—perhaps on the Big Sandy, in Kentucky. The following table represents the levels at which coal exists in the great Appalachian basin. By comparing this table with figure 117, it will be seen that the theory of elevation must be erroneous and singularly unequal; while that of depression, and contraction from volcanic ;action and condensation, answers every coincident and fits every circumstance, without the aid of miracles or natural phenomena, earth quakes, &c., which are unnatural and not natural processes, as described.
The coal measures of Illinois are stated by Prof. Wilber at 900 feet, which we presume to be nearly the maximum thickness, since it is not probable that the Pittsburg seam has any existence in Illinois, except in the highest portions of the southern part of the State. The deepest vertical section given in the Kentucky survey is about 1500 feet, embracing all the seams found in the Alleghany coal-field. If the Pittsburg seam exists, at all in Illinois, it must be on the highest points and to a very limited extent. Generally the workable seams lie below the Mahoning sandstone, and may safely be identified with B, E, and one of the cannel seams, which we cannot place. In the northern portion of the State only one workable seam is found, which is identical with B, or the seam worked by the Buck Mountain Coal Company on the Lehigh.
The principal mines of Illinois are located at Lasalle, St. Johns, Duquoin, Belleville, Danville, Rock Island, Carbon Cliff, Sheffield, Kewanee, Col Chester, Fairbury, Braceville, Morris, Caseyville, and Alton. The total amount mined and consumed per annum is stated by Wilber to be 650,000 tons. We presume the consumption, however, to be fully 1,000,000 tons, including the local consumption, which is not estimated above.