118 



stones. Like these, they are here underlaid by flag-like sandstones, sometimes 

 rather more argillaceous and approaching to clay slate, the whole passing down into 

 silicious sandstones, both thick and thin bedded. In the latter are casts of sever- 

 al fossils of the Caradoc formation, such as Pentameri of two species, and corals 

 peculiar to it. These fossiliferous strata are well exposed on the eastern side of 

 the hills by recent cuttings, where the new road from Bromsgrove to Birmingham 

 traverses the ridge. The ridge itself, however, consists essentially of quartz rock, 

 which the author shows is nothing more than altered Caradoc sandstone, precisely 

 analogous to that which he has on former occasions pointed out on the flanks of 

 Caer Caradoc, the Wrekin, Stiper Stones, &c. In those districts the passage 

 from a fossiliferous sandstone to a pure quartz rock has been accounted for by the 

 latter being in absolute contact with eruptive masses of igneous origin ; and here 

 it is suggested that the same cause may have operated, though the contact is not 

 visible, because the line of quartz rock is precisely upon the prolongation of the 

 trappean axis of the Rowley Hills, whilst the southern end of the parallel outburst 

 of the Clent Hills is but little distant. Notwithstanding their highly altered con- 

 dition, it is shown that all the quartz rocks throughout this ridge of low hills are 

 uniformly stratified, the dip being either to the E.N.E. or W.S.W., i. e. at right 

 angles to the direction ; and the parallelopipedal fragments into which the rock 

 breaks are shown to be produced by fissures more or less at right angles to the 

 planes of stratification ; these fissures being so numerous where the mass is much 

 altered, as almost to obscure the true laminae of deposit. 



4. Trap. — The composition and characters of the trap rocks and basaltic 

 masses of the Rowley Hills are first described, together with the manner in which 

 they are supposed to rise through and cut off the coal upon their flanks. Rocks 

 of similar origin occur at various detached points to the west of Dudley, of which 

 Barrow Hill is the principal, affording the most convincing proofs of the volcanic 

 mass having burst through the carboniferous strata, since the latter are not only 

 highly disturbed and broken, but fragments of coal and coal measures, in highly 

 altered conditions, are found twisted up upon the sides, and even mixed with the 

 trap itself. In the Wolverhampton or northern coal-field, the chief vent of erup- 

 tion is at Pouk Hill, two miles west of Walsall, where the greenstone is arranged 

 in fan-shaped columns. After pointing out distinct evidences of the intrusion of 

 similar rocks at Bentley Forge and the Birch Hills, in some of the old open 

 works near which the trap is seen to overlie the coal, the author gives various sec- 

 tions of subterranean works, which prove the existence of greenstone, in bands 

 more or less horizontal. As these bands of trap have jagged edges, are of limited 

 extent, of exceeding irregularity in thickness, and often produce great alteration 

 upon the inclosing carbonaceous masses, the author has no hesitation in expressing 

 his belief that they are not true beds, but simply wedges of injected matter which 



