Below we give two sections of the Primrose or G, one being the general type of the 1VIahanoy, and the other of the Schuylkill.
The average size of the Primrose appears to be about 12 feet in the Mahanoy basins. At some points it is larger, and generally in very good condition.
Mr. Francis Daniel, of the McNeal Coal Company's Mines, in the North Mahanoy basin, gives the Primrose vein as 16 feet thick in that locality, with 15 feet 6 inches of pure coal, and not over 6 inches of slate.
An enlargement of the Mammoth takes place at this point, which is nearly equal to the famous Lehigh quarry, and similar to the Mammoth at Miller's Shenandoah City colliery, or at the New Boston mines on the Broad Mountain, of which we have given an illustration in the description of that basin.
These great enlargements in the Mahanoy basins are generally on the north dips, where the veins are perpendicular and often double. We give the two sections of the Mammoth as proved in these two collieries. At the Shenandoah City colliery the operations are on the inverted north dips, and an enormous thickness of coal here exists in a very limited thick ness of measures. The veins are nearly perpendicular, but dipping to the south, though they are partly north-dipping veins. They are in the second or south basin, in the Shenandoah Valley. Of course, all the veins in the basin have a south dip in consequence, but the north dip is doubled back on the south dips, so that all the veins in the basin have the appearance of south-dipping strata. The accompanying illustration, figure 54, will clearly express this peculiarity.
This peculiarity, we may here state, is not confined to this locality. It is found in the vicinity of Mahanoy City, at the McNeal colliery, north of Locustdale, below Ashland, and in many other parts of the Mahanoy re gion. It is also a form of basin frequently met with in the Pottsville dis trict, and, in fact, throughout the Southern coal-field. It is not generally favorable to the condition of the coal or the economical working of the veins ; but sometimes the coal is found unaffected in quality by the increase in quantity, and the vein in good workable state, though greatly changed from its original and ordinary position.
This feature of the anthracite formation is but imperfectly understood by our miners, and frequently occasions much trouble. It gave an imaginary existence to the mythical jugular, and men are still found who are willing to spend their money on the strength of their faith in its reality, though abundant proof has existed during the last ten years that the jugular is simply an enlargement of the Mammoth, on the principle set forth.
This "vexed question" will be more fully explained under the head of "faults and irregularities." It will be noticed on the accompanying map of the anthracite coal-fields that a slender point of the Mahanoy basins extends far to the east and parallel with the Lehigh basins, and may, perhaps, more properly belong to that group than to the Middle coal-field, though the entire cluster is often included in this field. This point or slender finger of coal extends across the Catawissa Railroad towards the extremity of Head Mountain. A considerable body of coal exists in the most eastern basin, which is several hundred yards in breadth and probably seven hundred feet in depth. Messrs. A. Grey & Co., of Wilkesbarre, commenced to develop this basin in 1864: The coal on the south dip is imperfect, and the vein—probably the Buck Mountain—stands perpendicular,—the thickness of which was not known during our visit, but must have been over 20 feet. If the coal prove good, there is a considerable body Of it in the basin.
Farther towards the centre of the field, and on the west side of the Catawissa Railroad, two narrow parallel basins have been proved on the lands of Alter & Ste phens. Two of the lower veins are here found in work able condition.
It does not appear that the coal-basins are continuous at the eastern extremity, though the middle fork of the Mahanoy formation extends throughout. The con glomerate comes to the surface, however, at several points on this slender extension, and interrupts the continuation of the coal-basins. The extension is there fore formed by a succession of narrow and parallel basins, containing only the lower beds, which deepen, widen, and become continuous as they approach the waters of the Mahanoy.