The Mammoth bed, E, is here about 25 feet thick, and in very fine con dition, as shown by the accompanying section.
The Skidmore bed, D, is not fully developed on this property; and we could not get a perfect section.
Prof. Lesley, in his report to the company, marks the Skidmore as the "Ten-foot," and calls B the Skid more, which is also a mistake fallen into by Mr. Sheafer, from the imperfect development of the locality and the region generally, as both these gentlemen are eminently practical, and familiar with our coal-fields.
Bed C has not been developed here, but it undoubtedly exists. We have before stated that this is a comparatively small and irregular seam, but a persistent one, and en titled to a place in our columnar sections.
Bed B, the old Buck Mountain or "North vein," as here locally known, is developed in fine condition, as shown by the section. It ranges from 15 to 20 feet in thickness, producing most excellent coal. We doubt if this bed exists in any other locality in better condition.
A is found below B in its proper size and condition. It is known as the "rough vein," and is about 50 feet below B, in the conglomerate.
The vertical distance from B to E is about 250 feet, —perhaps more ; thus giving ample room for C and D. Above the Mammoth 150 to 200 feet lies the Primrose, or G; and between them is the small seam F, or the Holmes. The order in which the seams are distributed may be seen in figure 56, which conform to the positions and order of our general sections. The peciuliarity of the formation, however, gives more red-ash seams here, perhaps, than in any other portion of the Mahanoy region, as may be noticed in this transverse section.
One of the Mahanoy basins terminate west of Preston. The main or south basin is the only one continued to the extremity of the Mahanoy region, where the Ma hanoy and Locust Mountains intersect. The north basins die out about midway between Locustdale and the western termination of the south basin, or overlap the Locust Mountain.
We may here remark the existence of the third basin at Preston as drained by the Big Mine Run, opposite Ashland, which may be called the Centreville basin in that vicinity; but this basin properly belongs to the Sha mokin region, rather than to this portion of the Mahanoy since they are divided at Locustdale by the Locust Mountain, and drained by different streams running reversely. But on the Big Mine Run and on the Preston property the Locust Mountain becomes simply Locust Ridge, which is overlapped by the coal, and the mountain-range north of Locust Ridge there receives the name of Locust Mountain. The same occurrence
takes place west of Locustdale, or at Locust Gap, where the coal again overlaps the dividing ridge, as it does to the east. The name applied to this dividing ridge is geologically and topographically a misnomer. It takes its rise at the eastern end of the basin, and divides the Shenandoah from the Mahanoy, as the Locust Ridge, and runs parallel with Locust Mountain as far as Big Mine Run under this title, and nearly as far as Mt. Carmel, in fact. But from Big Mine Run this ridge, which rises and sinks alternately, is dignified with the name of " Locust Mountain," though that mountain really exists a mile to the north, and continues in a direct line many miles to the west, parallel with the ridge which from Big Mine Run usurps its name. But, more singular still, on crossing the coal-field these hills obtain a title to the Mahanoy Mountains; and that long range which bore the name of Mahanoy appropriately, resigns it to this usurping ridge.
The topography of the field does not justify this change of names, and the geological formations are distinctly opposed to it, since the axes of both synclinals and anticlinals are parallel and cross the ridge obliquely where it traverses the field. The name may have been locally and primitively applied ; but it is nevertheless a misnomer, and tends to confuse both the topography and geology of the section.
Figure 58 is a representation of the field at or in the vicinity of Locust dale. It is generally considered as composed of two basins; but the north basin is really divided into two distinct basins or synclinals. We may here notice, in order to make our description plain, that the Locust Ridge, on the right, divides the Mahanoy from the Shamokin region at this point by an unusual elevation of the conglomerate and red shale; while both east and west, at Locust Gap and Preston, this elevation is depressed, and the coal overlaps the mountain, forming a continuous field. The north basin is here separate and distinct from the Mahanoy region, and forms the south basin of the Shamokin region, as illustrated in figure 61, representing the West Mahanoy and Shamokin regions, c being the Locust Mountain, so called.