SALTER AND AVELINE ON THE CARADOC SANDSTONE. 



63 



beds ' could be identified with that * upper portion of the Caradoc ' 

 developed at May Hill and the Malverns, and which has lately 

 (vol. ix. p, 215) been described by Professors Sedgwick and M'Coy as 

 exclusively charged with Upper Silurian fossils, or whether they 

 formed a distinct series, intermediate between the Upper and Lower 

 Silurian rocks, and containing an intermediate group of organic remains. 



During the examination, the authors were able not only to confirm 

 the previous view of the physical connection of the beds in question 

 with the base of the Upper Silurian series, but to establish the fact of 

 a great unconformity between them and the subjacent so-called ' Ca- 

 radoc sandstone ' ; and the evidence of the fossils was found to be in 

 accordance with the geology. 



The fossils of the s»pposed typical Caradoc sandstone have been 

 already stated by Prof. Sedgwick to be the same with those of the 

 Bala group {I.e. p. 229). Not only are the forms identical, but in 

 association and proportionate numbers of the prevailing species it 

 would be difficult to mark any difference as compared with those of 

 Bala or Meifod. And there is no admixture of other or new forms, 

 or of those characteristic of higher parts of the system. This will be 

 shown in briefly noticing the character and fossil contents of its sub- 

 divisions. And in this respect they are in striking contrast with the 

 overlying grits and limestones of the ' Pentamerus beds,' which, 

 along the whole extent of the country under review, are characterized 

 by species nowhere to be detected in the adjacent Caradoc strata, 

 but which for the most part are the same as are found in the Wen- 

 lock strata, mingled with others more characteristic of this particular 

 horizon, and occasionally plentiful in the upper portion of the Llan- 

 deilo flags, such as the Pentameri. 



The strata that will now be brought under notice in more detail 

 are — 1. the various subdivisions of the rocks hitherto called 'Caradoc 

 sandstone ' in Shropshire (the lowest beds of which are cut off from 

 any inferior strata by great faults) ; 2. the Pentamerus sandstone 

 and limestone ; and 3. the lowest portion of the Wenlock shale. 

 The beds in a descending section are as follows : — 



Wenlock 

 shale. 



««2 



■^ ^ 



i1 



go 



*^ <x> 



s a- 



a, 



9. Grey rubbly concretionary shales, 

 1500 feet thick, with occasional 

 calcareous bands. 



8. Purple shales, 200 to 400 feet 

 thick. 



7. Thin limestone bands, interstra- 

 tified with ochreous sandstone, 

 and argillaceous shales (Penta- 

 merus beds). 



I 6. Conglomerates and sandstones. 



Localities where well exposed. 



? Wistanstow; HughleyMill; Build- 

 ) was, &c. &c. 



/■• Cheney-Longville foot-bridge; W. 

 3 of Hughley ; Belswardins brook ; 

 j N. of Buildwas ; S. endofLong- 

 C. mynds. 

 f Cheney-Longville ; Acton Scott ; 



near Soudley (the Hollies) ; Mer- 

 rish-wood, Harley ; Belswardins ; 

 Monell'sWood, near the Wrekin, 

 &c. &c. 

 Church Preen ; Kinley ; Harley ; 

 Morrell's Wood ; E. of Wrekin ; 

 S. and E. of Longmynds. 



