Great Coal-Jield of Shropshire, 209 



This bed is very distinctly stratified ; it rises N.W. at an angle of 

 about 65° where it rests on the Wrekin and Caer Caradoc, but in 

 the intermediate space at an angle of about 40°. 



Beneath the quartz-grit lies a very extensive bed of claystone or 

 compact felspar (for it presents the characters of both these minerals 

 in diflferent places, and even occasionally passes into jasper). Some- 

 times it is very distinctly slaty and stratified, which is particularly 

 the case with the lowest part of the bed, which rests on greenstone 

 and amygdaloid, and occasionally exerts a pretty strong action on the 

 magnetic needle. The craggy eastern side, both of the Wrekin and 

 of Caer Caradoc, consists of the slaty variety of this rock in nearly 

 vertical strata ; at the Arcal hill, it appears in the state of compact 

 felspar, covered to a considerable thickness by a mixture of fragments 

 of greenstone and felspar, more or less decomposing into a tenacious 

 clay ; it is nearly pure compact felspar at Wrockardine hill, the sides 

 of which are covered by a soft brownish-red very fine-grained sand- 

 stone, probably originating from the decomposition of the felspar. 



Under the claystone occurs an unstratified trap-formation which 

 constitutes the great mass of the Wrekin, the Lawley, Caer Caradoc, 

 Ragleath and Hope Bowdler hills, the various component parts of 

 which will be best understood by arranging them under the general 

 heads of felspar rocks and greenstone rocks. 

 1. Felspar rocks. 



The basis of all these is a claystone or compact felspar, of a colour 

 between flesh and brick-red, and they serve as the immediate support 

 of the superincumbent claystone. None of them affect the magnetic 

 needle. 



The variety which is most prevalent on the top of Caer Caradoc 

 is a cellular claystone, the cavities of which vary in size from that 

 of a small almond to a pin's head, and are all of them, especially the 



2 D 



