In the first place, the average distance of the Mammoth from the con glomerate is not over 300 to 400 feet, while the Pittsburg seam is from 700 to 800 feet. Now, as it is remarkable that the strata invariably de preciate or thin in a western direction, it would be singular and at vari ance with all our experience if the strata between the Pittsburg seam and the conglomerate should be greater at the Ohio than at the Schuylkill.
Secondly, we find the Pittsburg seam on the top of the barren measures, while the Mammoth is at their base, and the Primrose here occupies the place of the Pittsburg there. The great Mahoning sandstone seems cotemporaneous with the massive sandstone over the Mammoth ; and the Holmes, or F, corresponds with the single small seam in the "barren measures." Third, we find in the detached coal-basins lying between the anthracite and bituminous fields, the Mammoth in its proper position and character, as shown by figure 115, representing the Sullivan county coal-basin, which we give from actual and personal measurement.
We find the Mammoth also in its proper place in the Cumberland region, with the usual underlying seams; and we find, also, that the great bed of Karthause and Clearfield, in Pennsylvania, which is at the base of the barren measures, corresponds with the Mammoth in position and general characteristics; while we find the same bed on the Great Kanawha and on Coal River, in West Virginia, in the relative position of the Mammoth, and corresponding more generally with that great bed than the Pittsburg seam.
We are, therefore, forced to conclude that the first large seam below the barren measures, and on the same horizon with the Mammoth, is cotempo raneous with the latter, and that the Primrose bed, which is on top of the barren measures, and on the same horizon with the Pittsburg seam, is cotemporaneous and identical with the latter.
Under this theory it is possible to reconcile the anthracite with the bituminous formations; but it is not possible under the theory which takes for granted that the Mammoth and the Pittsburg seam are synony mous, nor under another theory, which makes the Mammoth identical with B in the Western coal-fields.*