NORTH, OR LYKENS VALLEY, FORK.
Passing west of Tremont and entering the basin of the North Fork, or Bear Valley, we soon lose all traces of the upper or red-ash seams; and the lower, or white-ash, also terminate with the measures in which they exist, as they successively rise to the surface. As we have stated, all our coal-fields exist as long, narrow troughs, with their extremities rising, like the ends of a canoe, to a point at the surface, as plainly illustrated in figure 22, representing the east-and-west undulations of the Wyoming basins. While the central portions of the field contain 15 seams, the ex tremities contain but one; and while the lowest bed at Pottsville may be 3000 feet deep, the lowest on the end of Short Mountain, west of Wicon isco, may not be over 20 to 30 feet.
The Gate vein, M, may be near the surface east of New Philadelphia and west of Swatara, but it ends near those points and traverses less than half the length of the field; and between these points and the extremities all the underlying seams come to day, or outcrop. This may be illustrated more clearly by the small diagram, figure 92. The practical—those familiar with our coal formations—will not require the aid of this figure to comprehend our description; but there are many who will require the aid of this plan, which shows very plainly why there are more coal-seams in the centre than at the extremities of the basins.
This illustration does not merely represent the outcrops of the seams in the north or Lykens Valley arm of the Southern coal-field, but is a general plan of the terminations and outcrops of the coal-seams in each basin. We have not given the parallel basins in each field as they exist side by side. It would be a mere repetition, and would tend to confuse rather than to instruct. We should be glad to see a correct representa tion of the position and outcrops of the respective basins in the First, or Southern, coal-field, for we confess ourselves unable to construct one. In fact, we know it to be impossible under present developments. An ideal plan might be constructed, representing the general features and groups of the Southern basins; but it would only be understood by those practically familiar with the peculiarities of the anthracite formations.
We may, however, convey a faint impression by comparing the basins in the First, or Southern, anthracite field to a fleet of Indian canoes laid side by side in a narrow stream. But some of these canoes should be very long and narrow, and others very short and comparatively wide; and, to complete the comparison, while they should lie seven or eight abreast in the centre, two should lie at the west end of the fleet, wide asunder, and only one at the east end.
The proportions in figure 92 are not correctly drawn, but it would be impossible to represent the formation on a natural or uniform scale. While the basin thus represented is not less than 70 miles long, it is only from a half-mile to a mile in breadth,—taking the first basin of the first coal field for instance,—and only 3000 feet deep, assuming their centres to be from 0 to 0 in the vicinity of Pottsville.
We have thus, perhaps, digressed from the subject under discussion, but have, we hope, conveyed a good idea of the general character of those terminating basins; and we shall not be required to state further why there are only two or three workable seams at Wiconisco and fifteen at Potts ville.
The Bear Valley seems to be a double basin, but in reality the measures contain three basins; they are not, however, all in Bear Valley. In fact, in Bear Gap, at Wiconisco, only one basin is shown in the valley; while the other two basins are, in a manner, under the mountains,—the south basin being under the southern base of Big Lick Mountain, and the northern basin being at or near the north base of Short Mountain.
We are aware the miners of Wiconisco think differently, and are under the impression that their coal-seams are below the conglomerate, forming a single basin from north to south under the valley and under both moun tains. But, if such is the case, all we have written is wrong, all our geology is at fault, and science has blundered seriously in the anthracite regions.