CHAPTER X.
Position[1] and Lie or the Rocks.
General Description.
The South Staffordshire coal-field seems like an island of Palæzoic rocks rising up through the secondary New red sandstone plain of the centre of England. These rocks appear at the surface partly in consequence of their being elevated to a higher level than the Palæzoic rocks immediately adjacent to them, which are still covered by the New red sandstone, and partly in consequence of the New red sandstone, which once covered them also, having been removed by denudation.
The general form of the Palæzoic district is that of a rather rude and irregular spindle-shaped band slightly bent so as to have both its sides convex to the west, and terminating in a point both to the north and to the south.
These points are at Barnt Green, which forms the southern termination of the Lower Lickey range, and at "Brereton Coal Pits," near Rugeley. They are very nearly 26 miles apart, and bear about N. 7° E, and S. 7° W.[2] from each other. Neither this line, however, nor its bearing, is of any importance, or requires further notice in the description of the district.
There are, however, two lines which can be drawn within the Palæzoic area which are worthy of notice in themselves, and indicate bearings that are very important, giving us, indeed, the key to the structure of the district.
The first of these lines runs from Barnt Green to the termination of the Sedgley Silurian ground near Parkfield school, south of Wolverhampton. This line is 14½ miles long, and bears as nearly as possible N. 22° W., and S. 22° E.
The second line starts from the south-west angle of the coal-field near Pedmore, and terminates at the Brereton coal-pits before mentioned. It is 22 miles long, and bears N. 23° or 24° E. and S. 23° or 24° W.
These two lines intersect m the town of Dudley, where they cross each other at angles of about 45° and 135°. A line bisecting the angle of 45° would run as nearly as possible north and south. A line bisecting the angle of 135° would be as nearly as possible east and west.
The first line runs along the ridge of the Lower Lickey, and is parallel to the general direction of the boundaries of the southern
