Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/223

 greenish yellow radiated glassy actynolite, a quarter of an inch or more in diameter, smaller concretions of quartz, intimately mixed with actynolite, and therefore nearly in the state of prasium, together with concretions and irregular veins of foliated white calcareous spar.

Of the above described trap-formation, it is not easy to ascertain its geognostic relations on the western side. The portion north of the Severn, which is by far the most extensive, is bounded by the old red sandstone; and the line of their junction is marked by the course of Strine brook from Newport to its confluence with the Tern, and thence by this latter to the point where it falls into the Severn. Along the greater part of this boundary line the two rocks may be observed adjacent, and in some places the sandstone appears to be incumbent on the trap-formation. The little coalfield of Dryton, on the Severn side, containing only two beds of thin coal, is certainly bounded on the east by the trap, but on the west seems to be adjacent to the sandstone.

With regard to the portion south of the Severn, it may be remarked, that the western and northern sides of the base of the Lawley, Caer Caradoc, and Ragleath, are overspread with a bed of coarse sandstone, consisting of angular fragments of felspar, hornblende, quartz, indurated reddish clay slate, and a little mica. This aggregate has by some been erroneously described as granite, and this mistake has led to the further error of considering the whole of the trap-formation as primitive. There are indeed detached rolled masses of true granite of considerable magnitude, as well as of other primitive rocks, in the near vicinity of the Lawley, but they occur only in a superficial bed of gravel that skirts in this place the southern boundary of the old red sandstone.

Patches of the same coal-formation as occurs at Dryton are distributed