BROAD TOP COAL-FIELD.
propose to include this small coal-field with the bituminous rather than the anthracite formations, though it occupies a place between the two, and, strictly speaking, is an independent field, belonging to neither the one nor the other, and is a peculiar semi-bituminous coal-field. Its coal is lustrous in appearance, like the anthracite, but square-fractured, like the bituminous: its place in our geology identifies it more nearly with the Western formations than with the anthracite. But, however we assign it, both bituminous and anthracite belong to the great Appalachian basin, and were the formations of the same era, the results of the same causes, and found in much the same conditions.
The Broad Top coal-field* is limited in area, but the accompanying vertical section demonstrates the amount of coal it contains to be in excess of the same area in any other outlying basin of the great bituminous forma tion. It contains four workable seams of fair dimensions,—larger, in fact, than the general size of the bituminous seams in other regions.
We fail to find, however, the "Big vein" of Cumberland and the Main moth of the anthracites; but the place it should occupy is filled by two seams, evidently synonymous with the Mammoth, which, as before observed, splits in its westward course. We think the coal presented in figure 113 is identical with the white-ash coal of the anthracite fields.
though we have named them, perhaps, differently. A is undoubtedly the counterpart of that given on or near the conglomerate as the bottom seam in the anthra cite regions. B we cannot fail to recognize as the Buck Mountain bed; while the next overlying seam, which is only one foot thick, must be C, or Gamma, of our nomenclature. It is always a small seam, seldom work
able, and often, even in the anthracite regions, as thin as it is here.
C, in figure 113, occupies the place of D, and is really the Skidmore. The seams marked D and E are un doubtedly the Mammoth; while the small intermediate seams may be splits of the same, or leaders, which we often find in the same ground in the anthracite regions.
The small seam, F, above the Mahoning sandstone— which is here 25 feet thick, and which is identical with the massive sandrock always found between E and F—is identical with the "Holmes." It overlies the Mammoth everywhere in connection with the great sandrock, known in the West as the 31a/toning sandstone, and is the only regular seam to be found in the "barren measures." It is always small, seldom exceeding four feet in the anthracite regions, and not often over twelve inches in the bitumi nous fields. It overlies the great bed of Karthause, and underlies the Pittsburg seam in the same manner as it exists above the Mammoth and below the Primrose in the anthracite measures.
In the Broad Top region the great Pittsburg seam is tand on the higher elevations, but too near the tops of the mountains, and covered by too small an amount of the overlying measures to be generally workable. We have not been able to get its exact position and dimensions, but understand its place to be about 400 feet above E, which is its proper position.
The following brief and concise account of this coal field is from the pen of John Fulton, Esq., the able engineer of the Huntingdon & Broad Top Railroad Com pany. .