quartzose gravel of the Drift period. Just south of the town it must be cut off by the fault which runs east and west from the south side of "the Moat." This fault is known in the Coal-measures to have a downthrow to the south of 120 feet. Its extension to the east is partly hypothetical, as from Walsall race-course no rock is seen at the surface either southward or eastward for at least a mile and a half.
In tracing the Thick limestone to the north it is seen to bend round and to be cut off by a small fault, a downthrow to the north, near "the Butts." Partly by reason of this downthrow, partly from the rise of the ground, the lower Coal-measures with the Blue flats ironstone here overlap the limestone, and run some distance to the east of its outcrop, till the gradual fall of the ground allows the Silurian shale to come to the surface again.
Near Rushall Castle is another little fault throwing down to the north, but here the Thick limestone again crops to the surface, in consequence of the denudation of the Coal-measures, and has been worked in quarries towards the north-east as far as Linley. In some of the quarries between Rushall Castle and the Halfway House the Coal-measures may be seen on the west side of the excavations resting on the Silurian shale; but the Coal-measure boundary shortly strikes north, while the Silurians strike north-west, in consequence of which at Daw End the Upper or Little limestone comes out from under the Coal-measures, and may be traced by a line of old quarries running in a curved line down towards Ketton's garden. In the canal near here a small supplementary band of limestone is found between the two limestones, and towards the Halfway House a short band of limestone was worked below the Thick limestone. These masses are called "Self lumps;" they are large lenticular masses, in which the calcareous so far prevails over the argillaceous matter as to form good workable limestone.[1] North and east of Daw End the Silurian rocks are altogether cut off by a great fault, which we may call the Daw End and Linley fault, running north-west and south-east, throwing down to the northeast and bringing in the Coal-measures in that direction.
In this Coal-measure tract was sunk the Trial pit at Aldridge (see Vertical Sections. Sheet 16, No. 4), and another pit between Aldridge Lodge and Hill End. This latter pit. I was informed by Mr. Roberts of the Butts, was 62 yards deep, and that three measures of coal and two of ironstone were passed through, the whole dipping east-southeast at an angle of 25°.
Starting from the Walsall and Daw End limestones, and traversing the ground to the east, we find here and there small openings or cuttings in the shale below them, but we do not get much information till we come to the banks of the new canal running from Longwood Wharf south-south-west by Ginity Graves and the Bell to the Tame Valley canal that runs by Bustleholme Mill and Ray Hall. All down this canal are cuttings in Silurian shale or "bavin," for the most part as nearly horizontal as possible.[2] East of it, about Hay Head, we get another limestone rising from underneath this shale at an angle of about 10°, running from the fault near Aldridge Lodge down to Daffodilly, where it begins to curve and dip at a high angle, finally ending against the "red rock" near the Skip, its last piece dipping south-west at 35°. East of this, which is locally known as the Barr limestone,
- ↑ It must be borne in mind that all the Silurian shale near these limestones is more or less calcareous, and full of calcareous lumps and nodules.
- ↑ In cutting this canal a number of fine fossils were discovered, especially heads of Eucalyptocrinus and Echinoencrinus, also many fine and rare brachiopods.
