LUDLOW SERIES. 



105 



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it was in local use in Caermarthen- 

 shire and Brecknockshire, yet there 

 is not a stone capable of being 

 formed into a //k from the Downton 

 Sandstone to the Cornstones of Wall 

 Hills ; but there are thin muddy 

 marls over the Downton beds, which 

 would have been tilestones had they 

 been sufficiently hardened, and which 

 are doubtless equivalents of the true 

 tilestones.^ The Passage-beds have 

 been observed also in Pembroke- 

 shire, as well as in Gloucestershire, 

 Worcestershire, and Shropshire. 

 Murchison has stated that the tile- 

 stones are visible all along the eastern 

 frontier of the Silurian rocks, and 

 scarcely exceed 40 or 50 feet in 

 thickness. 



The term Downton Sandstone 

 (used by John Phillips) is now ap- 

 plied to the lower portion of the 

 Passage-beds, the Ledbury Shales 

 constituting the upper portion. 



Among the fossils of the Downton 

 Sandstones are Land-plants, Actino- 

 phyUiim, Chondrites, and Lycopo- 

 diaceous seeds; Annelides, Comulites 

 and Serpulitis; Crustacea, Beyrichia, 

 Ctraiiocan's, Plerygotus Liidcnsis, P. 

 prohltviaiicus, Euryptej-iis, etc. ; Mol- 

 lusca, Lingula cornea, Platyschisma 

 helicites, etc. ; and Fishes, Onchus 

 tenuistriatiis, Cyathaspis, Pteraspis, 

 etc. The organic remains indicate 

 shallow-water conditions. 



Fossils may be found near Builth, 

 at Bradnor Hill, near Kington, in 

 Radnorshire, and near Trimpley in 

 Worcestershire," etc. The beds have 

 been exposed at Hagley Park,^ also 

 near Ledbury, and near Ludlow.^ 



1 W. S. Symonds, Q. J. xvi. 196. 



2 R. W. Banks, Q. J. xii. 93 ; G. E. 

 Roberts, Geologist, ii. 117. 



3 H. E. Strickland, Q. J. viii. 381. 



* A. Marston, G. Mag. 1870, p. 408 ; W. 

 S. Symonds, Q. J. xvi. 193, 

 = Q. J. xix. 178, fig. 2. 



