Just at the south end of Pelsall Heath, the Bottom coal, which up to that pot has been worked continuously as a single twelve-foot coal, begins to separate into two coals, which about a mile or so farther north are as much as 15 yards (45 feet) apart. These two coals were formerly gotten along their outcrop at the Brown Fills, under the name of the Shallow and the Deep coal. The Deep coal itself is also, a little farther north, beginning to separate into two coals.
The Fire-clay coal has been worked continuously from Bilston up to Bentley, and thence by Goscott to Pelsall, but on reaching the latter place it apparently begins to change its quality and character, and further north is known only as the Cinder coal.
The New Mine coal crops out a little before it reaches so far north as the Great Bentley fault, and when thrown in by that fault, it is found to be separated into two, called at Bentley the Three-foot and Five-foot, but known farther north as the Yard and the Bass coal. That these two coals are in reality the two separated parts of the New Mine coal is shown by the fact that at Bentley they have the Sulphur and Heathen coals next above them, and the Fire-clay coal next below them.
With this tendency to split up into separate coals as we proceed towards the north, clearly proved to exist in the lower beds which run continuously in the ground, we can the more readily allow the probability of a similar tendency in the upper beds, which now only occur in localities more widely separated from each other in consequence of the removal of large portions of the measures by the denudation that has acted over the intermediate space.
In consequence of the denudation having removed so much of the upper measures it is difficult, perhaps impossible, to identify the beds of those upper parts of the two districts with the same precision that we can the beds in the lower measures. It is, however, very remarkable that if we add together the average thickness of the coals in the Wyrley and Essington district, commencing with the Old Robins coal, and including the Essington four-foot or Bentley Hay coal, which there lies next above the Heathen coal, we shall, if we omit the partings, get a thickness of a little over thirty feet (about thirty-three feet), which agrees quite as closely with that of the Thick coal as we could expect.
Whether the Brooch coal of the district south of Bilston, be represented by the Essington sixth coal, or whether the fifth and sixth coals of that locality be new coals, and the third and fourth represent the Brooch, is perhaps a moot point.
If the Old Robins coal be really the top of the Thick coal, or the same as the Flying reed coal, then the Essington sixth coal is at rather a less height above it than the Brooch is above the Thick coal in the southern part of the field. Bearing in mind, however, the tendency to thicken and increase towards the north which the measures below exhibit, we should expect the height to be greater, and should be more inclined, perhaps, to look upon the fifth and sixth coals of Essington, either as themselves the representatives of the Flying-reed, or upper part of the Thick coal, (which will
