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VI.—Notes on the Geology of the Brown Clee Hill, in the County of Salop.

BY ROMLEY WRIGHT, ESQ.

Employed on the Ordnance Trigonometrical Survey of England.

[Read Dec. 18, 1838.]

THE old red sandstone which forms the base of the Brown Clee Hill*, gene­ rally dips from 5° to 10° to the east and south-east. Its lowest beds are re­ markably soft and clayey; but through a large portion of the counties of Hereford and Salop, it almost invariably contains one or two beds of lime­ stone., provincially called cornstone, and much used for agricultural purposes. The old red sandstone, as it rises towards the Brown Clee Hill, instead of continuing to dip towards the south-east, gradually assumes a basin-like form ; inclining on all sides towards the centre, at an angle of about seven degrees. A bed of cornstone, about twelve feet thick, ranges almost entirely around the hill; and a second bed, also much quarried, occurs above it. From the circumstance of these two beds reposing in the form of a basin ; and from their proximity to the superincumbent coal deposit, they appear to have been considered as representatives of the mountain limestone: but 150 feet of the old red sandstone lies between these cornstones and the coal mea­ sures, and passes on the western side of the hill into a regular conglomerate. Immediately upon this conglomerate, the coal formation reposes; its greatest thickness being about 150 feet; and the dip of the beds conforms to that of the subjacent strata, or towards the centre, at angles varying from 3° to 5°. The outburst of its lowest bed, locally termed the " Bottom Rock," is marked by a soft white clay, which freely throws out springs of water. This e( Bottom Rock" has but little quartz, and in grain resembles whitish oolite. Coal has been discovered, to the amount of six feet in thickness, distributed in three different veins, namely, The Three-quarters Vein ... 1 foot 7 inches. The Batty Vein 2 feet 6 inches. And the Bottom Vein 2 feet. When worked it is chiefly by means of a windlass ; but the beds are neg- * Plate VII. 126 Mr. WRIGHT on the Geology of the Brown Clee Hill. lected in consequence of the superior quality of the coal which is found three or four miles distant, in the Titterstone Clee. There are three separate faults, ranging nearly parallel to each other in a north-east direction*. The first, which is but a few inches in width, throws up the coal veins about three feet on its south-eastern side; the second throws them up about five feet; and the third, which ranges near the centre of the superincumbent mass of basalt, called the Clee Burf, is about thirteen yards in horizontal thickness, and throws up the measures nearly nine yards. The " Wall/' as this last fault, or the basalt which accompanies it, is termed by the miners, is so hard as to require to be blasted, no tools which they possess being able to work it; but the coal in immediate contact with the basalt, is represented as not being in the least charred. It may be followed on the surface for about 400 yards, and in the prolon­ gation of this line, the measures are found in abrupt and unconformable contact with the old red sandstone; the lower beds of which also lose their continuity, as may be observed above Pickleton Grange. The coal field of the Brown Clee Hill, comprises nearly two square miles, and, owing to an inosculation near the middle of the hill, its outline much resembles a figure of 8 (see Plate VII). Within its area are two isolated caps of basalt, forming the highest points of the hill, namely, the Abdon Burf, exceeding 1800 feet above the level of the sea; and the Clee Burf, which is about 200 feet lower. The basalt of Abdon Burf appears to be about 140 feet thick, but it has very extensively fallen down, and now appears only in the form of large blocks of stone. To the eye the basalt precisely agrees with that of Rowley Regis, near Dudley; and is much finer grained than the basalt at Earls Shilton in Lei­ cestershire. From the large fault in the coal measures, specimens of the rock were obtained, similar to the overlying mass of basalt. After the most careful and repeated examinations, no traces of a columnar arrangement could be per­ ceived in the basalt of the Brown Clee Hill. Prom the almost inaccessible nature of their situation, each of these two hills was formerly occupied as a for­ tified post, in the same manner as the Titterstone Clee. At Bouldon, about two miles distant, there was formerly an iron furnace, and it is generally believed that the ore was obtained from the Brown Clee Hill. Immense heaps of refuse are yet seen, from which the metal has been but very partially extracted. It is certain that iron ore is associated with this coal deposit; but its site is not sufficiently known to admit of being introduced into the accompanying plan; for the same reason I have omitted to mark the outburst of the beds of coal. * Plate VII. Map and Section E. F.