THE GATE.
This is the upper reliable seam in the anthracite regions, and is perhaps the most valuable of the strictly red-ash veins above the Primrose. It is extensively worked, and has been mined to a great depth at several distinct and distant localities,— for instance, at the York Farm, by George H. Potts; at the Old Salem colliery, near Port Carbon; at the Novelty colliery, below New Philadelphia, and several other points, —and has generally been found consistent, uniform, and less troubled with faults than most of the red-ash beds of an earlier formation,—a singularity that we can scarcely account for except by the theory of "gradual depres sion." This seam ranges from 4 to 16 feet in thickness; but its usual and best condition is from 5 to 10 feet. The south dips, though more consistent in size, are generally the smallest in diameter; while the north dips are usually of greater dimensions, but generally not so reliable or regular. A singular feature of this seam is the fact that a north dip is seldom found on the surface or at its outcrops. This feature, however, to a limited extent, prevails with the veins immediately below it, and to the same extent to the one above it. This is readily explained by referring to figure 74, where it may be noticed that all the north dips incline at first to the south in the first basin; and this feature governs the upper seams to a greater extent than our section represents, even in the third and fourth basins. In fact, nearly all the north dips in the Pottsville district are either inverted or perpendicular : consequently, the outcrops of nearly all the seams would appear as if they were dipping to the south; and this feature originally, or when this field was first developed, was a great mystery to geologists and miners. Those who knew little or nothing of geology supposed that we had as many distinct seams as we had outcrops, and that instead of 14 workable beds we had 140 or more. Whether they all united in a great mass below, terminated in needle-points, cut each other off; or dipped under the Sharp Mountain and came up in some other unknown country, were debatable questions which were often argued, but we believe never satisfactorily settled or concluded.
We believe that M was first worked at Centreville, under the name of the "Sphon," and subsequently at Pottsville, in the Gate ridge, under the name of the Gate ; at the Salem colliery, near Port Carbon, as the Salem ; at the Delaware mines, as the Peach Mountain ; and at the Mill Creek colliery, as the Lewis. At each of these points this vein was worked in
different basins and on different dips, and under different names as distinct seams. Even now many of our old and intelligent miners are slow to credit the fact. To them it seems inconsistent that the Gate and Salem can be the same vein, since they both appear to dip in the same direction and are apparently in the same basin. It is difficult to convey an intelli gent impression of the inverted dips in our anthracite basins to the minds of men accustomed to the uniform and gentle undulations of the English coal-fields; but we hope our illustrations will convey the idea more successfully than our simple descriptions.
This feature of inverted dips has not only mystified the formation in the southern or deep basins below the red-ash seams, but has been the cause of much confusion and error in connection with the Mammoth in the white-ash or northern basins. Thus, the inverted dip of the Mammoth at Coalcastle, as illustrated in figure 75, gave rise to the fabulous Jugular bed which has been the means of draining the pockets of many. But the Jugular has never been found; though some are still driving tunnels in search of it. They may be rewarded by the discovery of the Buck Mountain, or B, in a workable condition ; but, as the famous Jugular is a myth, its believers will never be rewarded for their faith.
The Gate, or M, has, of course, less range than the Tracy, or K, before described, and probably does not cover more than 60 square miles of area throughout the anthracite regions. Its superficial area, however, is less than its real area, if horizontally stratified, since the basins in which it exist are contracted to less than half their original dimensions, until the veins are frequently " on end," instead of being in a naturally stratified basin. At the Roads Shaft colliery, near New Philadelphia, M is found dipping at the rate of 80° south, while in the Sharp Mountain, opposite, this bed is perpendicular and frequently inverted. It is almost impossible, under such circumstances, to tell how deep the basin may be, or how wide it originally was. But this contraction does not take place in shallow basins ; for, instead of being depressed, they are lifted by the contracting forces, and we may thence conclude that all perpendicular dips having long axes must belong to deep basins.
The Gate at the Roads colliery will average 10 feet thick, with 7 feet bottom bench, and a 2 feet top bench, divided by a foot or more of slate.