"The division of the Bunter beds into three sub-formations was first made out by Mr. Hull while mapping the New red sandstone near Coalbrook Dale, and I considered it so important that, with the approval of the late Sir Henry De la Beche. I instructed the members of the Survey engaged on the New red sandstone to map all the subdivisions, more especially as in doing so we had a means of detecting a number of the faults that traverse the country.[1] This accordingly has been done from the south end of the Malvern hills to Lancashire and Nottinghamshire, and the sub-formations have been found always to maintain the same order of superposition, although occasionally one or more members may be absent. In general they are easily distinguishable from each other, except when the Upper and Lower Red and Mottled sandstones chance to be brought together by faults. All of them occur in the district described in this Memoir."
Keuper.—The Red Marls—This subdivision is principally composed of marl of a dull red colour, with occasional thin bluish shaly beds, containing sometimes small layers of bluish-white sandstone a few inches thick. In the bottom part of the marls occur local beds of sandstone some feet in thickness, sometimes brown, sometimes yellow or white, containing few or no pebbles, generally rather shaly, and not often marked by oblique lamination. The marls are likewise generally shaly, and are sometimes slightly arenaccous, especially in the lower beds. Like all marls, they, when dry, frequently crumble into small cuboidal fragments.
In Staffordshire neither the gypsum nor the salt of this subformation is very abundant. Beds of gypsum may be seen cropping to the surface in several places about Tutbury and Uttoxeter, and the substance is met with elsewhere in wells and pits. The salt is only known by the occurrence of brine springs, which are met with at two places, one at Silkmoor, 1½ mile south of Stafford, the other at Shirley Wych, near Weston-upon-Trent. At the latter place there is a shaft sunk to the depth of 414 feet, of which Mr. Hull procured the following section:—
| FT. | |
| Drift sand and gravel | 54 |
| Gypsum | 6 |
| Red marl | 354 |
| 414 |
It is probable, therefore, that the total thickness of this subformation cannot be much less than 600 feet.
Waterstones.—"At the base the Red marl passes into or rather alternates with beds of white and brown sandstone, formerly considered the uppermost part of the Bunter beds, but now placed by the survey as the lowest member of the Keuper series, and called the Lower Keuper sandstone or Waterstones. These strata are the
- ↑ This may some day throw much light on the mode of working the coal below, should it ever be searched for and found.
