Between these two last faults, on the north-west side of the ridge, a piece of the upper limestone only reaches the surface, just as a similar piece did between the two faults on the north-west end of the Castle Hill.
In the valley between the Wren's Nest and the Castle Hill repose the lower beds of the Coal-measures, the Bottom coal running some distance into it, both from the north and south ends of it.
Coal-measures likewise stretch between the Wren's Nest and the Sedgley Silurian district, but these are only the sandstones forming the base of the formation, and they lie only on the higher parts of the ground, the bottom of the valley north-west of the Wren's Nest showing Silurian shale at the surface.
The Sedgley District is rather a complicated one.
Hurst Hill.—On the east side of it is Hurst Hill, where the Wenlock and Dudley limestones rise into a long oval anticlinal ridge, like those of the Wren's Nest and Castle Hill, but not so perfect. At the southern end the two limestones bend round and abut against the base of a piece of the upper limestone, a fault running between the two; this piece of the upper limestone must be cut off each way by faults, and a fault dropping down to the west runs along the whole of the remainder of that side of the ridge, preventing the appearance of the limestones. On the eastern side the beds strike north, dipping cast at a high angle, they are broken through by a small east and west fault just south of the Cann Lane road, but from that spot strike still north till they curve round the northern end of the ridge, and dip in that direction.
They have been followed under ground north of the hill for 200 or 300 yards, dipping generally north at about 30°, and ending towards the west against a fault which runs about north-north-west, and which must be a downcast to the west.
Sedgley Beacon.—West of Hurst Hill is a rising ground formed of the Ludlow rocks, containing the band of limestone before described as the Aymestry and Sedgley limestone. These at first dip west at an angle of 10° to 20°, forming a pretty bold escarpment towards the east known as Sedgley Beacon Hill. The limestone, however, soon rises again to the west, and forms a cap to the high ground south of Sedgley, and after undulating a little in various directions, finally crops out on the west side of the hill, dipping cast at 10°. North of Sedgley this cap does not appear, the Silurian beds forming a basin instead of a cap, and only cropping out on the west side of the Wolverhampton road, where they dip pretty regularly to the east at an angle of 20° for about half a mile. 'They then appear to curl over for a short space, and dip north-west at 35°, but I believe this is only a local flexure, and that the limestone beds curve round from this point to meet those of the Beacon Hill quarry. About one third of a mile north of that, however, the limestone again appears suddenly at the surface, dipping north-east at 60°, its northern end curving round till it dips north and north-north-west, at 15° and 20°, and then suddenly ending. 'The faults drawn on the map are the most obvious explanation of this peculiar position of the rocks, though with the exception of the one on the west side of Hurst Hill, they are all put in hypothetically. In the hollow of the Silurian rocks north of Sedgley the sandstones forming the base of the Coal-measures again occur, as shown on the map. About half a mile south of Sedgley the Silurian rocks must be cut off by an east and west fault, a downcast to the south, which brings in the Coal-measure sandstone on their level.
Turner's Hill.—These lower sandstones spread over the ground from Upper Gornal, by Ellows Hall, to Lower Gornal, undulating in various
