Besides these four, there are two very well marked, although only small troughs, which are known in the northern part of the field. The one is that of the High Bridge in the Pelsall district, and the other that which we may call the Rising Sun Trough, down the centre of which Watling Street runs from the old inn called the Rising Sun to the eastern boundary fault.
CHAPTER XI
Position and Lie of the Rocks.
Detailed Description.
The preceding chapter is intended for the use of the general geological reader, who wishes to gain merely a general notion of the structure of the district; read with the maps before him it may be sufficient for his purpose.
In this chapter it is intended to describe in a little more detail the features there sketched out, and to give some of the data on which the descriptions are founded.
We will first of all describe the main line of division before mentioned in Chapter X,. commencing with the northern part of it, namely, the Dudley and Sedgley anticlinal.
MAIN LINE OF DIVISION OF THE COAL-FIELD.
The Dudley and Sedgley anticlinal is not a simple one, but very complex. There is one general broadish area of elevation which may be said to be defined by the outcrop of the Thick coal. Ranged, however, on this wider and gently-elevated region there are three smaller areas that have each suffered from a maximum intensity of elevating force, namely. Dudley Castle Hill, the Wren's Nest, and the Sedgley district, including Hurst Hill. The axes of these three areas of Maximum disturbance do not run parallel to the general axis of the elevated tract, but cross it very obliquely, running nearly true north and south. They would thus appear to be the result of the nearly equal action of the two prevailing lines of disturbing force before mentioned, as they run in a direction equidistant between them.
Dudley Castle Hill.—At Dudley Castle Hill the two bands of limestone rise boldly out on the south, at angles varying from 25° to 30°, curve round with great symmetry and regularity on each side, and stretch off to the north in a narrow ridge, the sides of which dip east and west respectively from its central portion, see Fig. 18. As they run north the inclination of the beds increases to 50°, and the two pieces of the lower limestone nearly meet each other on the crest of the ridge. On the east side the limestones begin at Shirts Mill to curve regularly round towards the north-west, dipping north-east, and then towards the west, dipping north at 10°, but are then suddenly cut off by a fault. The limestones on the west side are cut off by a fault
