Great Coal-Jicld of Shropshire. 211 



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, to- 

 gether with concretions and irregular veins of foliated white calca- 

 reous 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 Dry- 

 ton, 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 re- 

 marked, that the western and northern sides of the base of the Law- 

 ley, 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 aggre- 

 gate 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 primi- 

 tive 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 Dry ton are distri- 

 2 D 2 



