THE SHAMOKIN REGION.
This, as we before stated, is the western end or portion of the Middle coal-field, and is perhaps the "largest half," though the field is nearly equally divided by the Locust Ridge or so-called Mountain. The eastern or Mahanoy region is estimated to contain 41 square miles of coal area; while the western or Shamokin region is put down at 50 square miles of coal area, —the total area of the field being 91 square miles. This portion of the field is wider in its centre than the eastern portion, and the undulations are more numerous, but they are not generally so abrupt or their angles so great. There are exceptions; but the basins, as a rule, are neither as deep nor as steep in their dips as those of Mahanoy. The accompanying illustration, figure 61, will portray this difference as compared with figure 51.
Figure 61 represents a section across the western end of the Mahanoy region and the central portions of the Shamokin region. The Mahanoy Mountain is on the left; a is the Locustdale basin, west of that point; b is the Bear Ridge anticlinal; and c the Locust Ridge, or so-called Moun tain; d is the central or deep basin of the Shamokin region ; and e the location of the town of Shamokin; while the mountain on the right end of the section is the Shamokin Mountain. The breadth of this portion of the field, or the Shamokin region, is from c, or the Locust Mountain, to the Shamokin Mountain, a distance of three miles or over.
Though the basins of this section are less in depth than those of Ma hanoy, and more uniform in dip, with lesser angles of inclination, their "strike" or prolongation on uniform axis is much less regular and reliable, and the size and character of the veins are depreciated. The coal is gene rally very good, but the veins are smaller, and, consequently, less produc tive, in the central and western parts of the region. But in the southern part, or north side of the Locust Mountain, they have the same dimensions and excellence which distinguish them on the south side of the mountain; but they depreciate in size and character to the north and west. The coal becomes softer, particularly at the western extremity, or at Trevorton, where it assumes the character of a semi-anthracite. But though the seams are less in size, they are more in number, and have the appearance of having, in some instances, been divided. This is manifestly the case with
the Mammoth, which is here known as the "Twin veins." There are also several indefinite, irregular, and unreliable veins in the conglomerate below the position of A; but to these we shall pay no attention, because they are merely local deposits and have no uniform existence or consistent place in the anthracite coal measures.
We are guided more by the developments and investigations of William H. Marshall, Esq., of Shamokin, and the practical experience of the older operators, in regard to the formation of this region, than by the geology of the field by 'Professor Rogers. But we may here state a fact which our readers may notice. We have followed no predecessor, and copied no stereotyped opinions or theories, but have, with much labor and perse verance, collected the data we have used from hundreds of practical sources, and have endeavored to evoke system and uniformity out of the heretofore confused and diversified character given to our coal-fields. We have thoroughly identified the seams, and shown a consistent uniformity throughout the anthracite regions. Yet we must confess an uncertainty and doubt in our classification within this region. The veins are less characteristic, and present few of the identifying types we meet in other regions; but this peculiarity is perhaps more local than general, and our lack of personal familiarity with the entire region may prevent a proper appreciation. As formerly stated, we have every reason to believe the coal-seams are consistent throughout the anthracite regions, and occupy, respectively, a uniform place in the coal measures. We have, therefore, taken the Mammoth or Twin veins as a base, and applied our nomen clature here as elsewhere, omitting the seams found in the conglomerate below A, since those veins are not consistent even here, and are not found generally in any other portion, of the anthracite fields. Rogers makes E, or the Twins, his eighth and ninth veins, independent of a small, irregular seam found far down in the conglomerate, which he names "zero." We have not represented the two lower seams as found at Trevorton or Zerbe's Gap, and have only traced the third and fourth in the conglomerate below A.