Page:The South Staffordshire Coalfield - Joseph Beete Jukes - 1859.djvu/152

194 east, there comes out at Hay Head, near Barr, a lower limestone than has been seen in any other portion of the district.

A little to the east of that Barr limestone or of the beds which represent it, the May Hill or Llandovery sandstone, which lies next below it, makes its appearance, and would be much more largely exhibited if it were not immediately cut off by the boundary fault a little to the east of Shustoke Lodge, while near Hay Head it is concealed by a thin skirt of Coal-measures lying unconformably upon it, before both are thrown down by the boundary fault.

South of the true coal-field lies the Silurian district of the Lickey, where these same sandstones rise up from beneath the shales containing the representative of the Barr limestone. These also were elevated and denuded before the Coal-measure period, as we find thin Coal-measures resting directly upon them. It appears then that previous to the deposition of the Coal-measures there was here a broad and generally level plain of Silurian rocks {whether above or under water), the beds of which had a slight dip to the west, and cropped out successively towards the east, at the surface of the plain. The boundary of the Ludlow formation must have run somewhere along the line before mentioned, that of the Wenlock nearly along the line of the eastern boundary of the coal-field, while the Llandovery rocks spread some distance farther to the east. If any of the outcrops formed escarpments, they must have been low and gently sloping.

That this gradual rise to the east was continued yet further in that direction beyond the bounds of our district, is rendered probable by the fact of rocks still older than the Upper Silurian (perhaps older than any Silurian) appearing in the Warwickshire and Leicestershire coal-fields, with the Coal-measures resting directly upon them. It is, indeed, highly probable that all this tract of country, together with much of the adjacent district from Montgomeryshire to Leicestershire, became dry land after the close of the Silurian period, rising, perhaps, very slowly, and undergoing a very gradual and long-continued process of degradation as it passed through the destructive plane of the sea level; and that it remained above the waters during great part of the period marked by the formation of the Old red sandstone and Carboniferous limestone, and that accordingly those two rocks were never deposited upon it.

However that may be, we find that when the Coal-measures of South Staffordshire came to be formed, their earliest beds were deposited on a rather rough and cliffy (see p. 80, and Fig. 11), but generally horizontal surface, and that the dip of the Silurians, though still markedly to the west, was so slight that their beds could not at any one place have been seen sensibly to differ in inclination from the horizontal or pearly horizontal beds of the Coal-measures. We have already, in examining the base of the Coal-measures, seen the way in which at particular spots the lower beds of that formation filled up hollows in the Silurian rocks and obliterated their little pre-existing cliffs, and thus formed