under the New red sandstone, either in consequence of their continued dip, or from their being suddenly thrown down by downcast faults in those directions.
If now we return to the high ground stretching through the Clent Hills and Frankley Hill, and descend its northern slopes towards Halesowen, we shall see that the beds of Permian rise gently to the north, and that at the foot of the slope the Coal-measures appear from underneath them. These Coal-measures consist, first of thin grey shales and clays, then of the Halesowen sandstones, and then of red clays, each successively rising out to the surface towards the north as we descend into the valley of the Stour.
We are here fairly within the coal-field which thence runs off continuously to the northward, or a little cast of north, between its boundary faults, till we arrive at Hednesford and Brereton. The boundary faults are sometimes single large downthrows bringing the New red sandstone into direct contact with the Coal-measures, and are sometimes more complex, allowing of the appearance of more or less of the Permian rocks between the Coal-measures and New red sandstone.
At Hednesford and Brereton the two boundary faults seemingly run off into the New red sandstone, and over the space between them the Coal-measures are apparently covered by an overlap of the New red sandstone resting unconformably upon them. It is probable, however, that the Coal-measures are here, either let down by faults, or largely eroded under the New red, which formation probably thickens much more rapidly to the north than would be supposed by the mere inclination of the beds.
The coal-field then is a narrow plateau of Coal-measures bounded both on the E, and the W. by downcast faults, covered on the north by unconformable New red sandstone, and dipping on the south under apparently conformable Permian rocks.
The coal-field itself may be divided into two parts, each of which may be again subdivided into two.
The principal line of division in the coal-field is that which runs from Parkfield a little south of Wolverhampton, through Sedgley. Dudley, and Rowley, to the Leasowes. This line forms a broad anticlinal ridge from Parkfield to Dudley, round which ridge the coals all crop out, and on which the Silurian rocks rise to the surface at four places. Three of these, namely. Dudley Castle Hill, the Wren's Nest, and Hurst Hill form long oval elevations of the Dudley limestone, the axes of which run north and south, with the beds curving round at very high angles, but more broken by transverse dislocations than they seem to be at first sight. The fourth, namely, the Sedgley ridge, is a broader and more irregular synclinal flexure, the axis of which is likewise north and south, and which is also broken by faults.
