Murchisoris Silurian System. 215 



" The limestone at Le Batwood is extensively burnt for lime, and 

 is identical with that of Pontesbury and Uffington, containing also 

 the Microconchus carbonarius. It is about two yards thick, and lies 

 from eighteen to twenty yards below the surface. A three feet bed 

 of coal, found at eleven yards below the limestone, is of a sulphureous 

 quality ; and six yards still lower is a seam, twelve inches thick, of 

 good coal. In the limestone, besides the usual shells, the remarkable 

 species of fish Ctenodus Murchisonii (Agassiz) was found by the very 

 .Rev. Archdeacon Waties Corbet; and Professor Phillips detected, in 

 the shale, remains of the MegalicJithys Hebberti, fyc, on the western 

 edges of this bay. Amid the older rocks, coal has been worked near 

 Pulverbatch, Wetrains, &c. ; and on the eastern side it has been de- 

 tected, and was partially worked in former days, running up in small 

 transverse valleys towards the Caradoc and Acton Burnel hills. One 

 of the most curious of these thin patches is displayed on the west 

 bank of the brook at Bitchford. The whole carboniferous series is there 

 represented by a bituminous breccia, from ten to twelve feet thick; 

 which is partially covered by the new red sandstone, and rests upon 

 the highly inclined edges of a greenish greywacke sandstone (Cambrian 

 rock), similar to that of the Longmynd. 



" The highly inclined edges of these Cambrian rocks, which rise to the 

 height of only from twenty to thirty feet above the brook, are, on the 

 western side of it, covered with the carboniferous breccia arranged in hori- 

 zontal layers ; but as the works were abandoned when I visited the spot, 

 I could not observe the junction between these beds and the inclined 

 edges of the older rocks. This breccia is composed of fragments of the 

 underlying Cambrian rock, on the surfaces of which are casts of ferns 

 and other coal plants, the whole being cemented by bitumen and de- 

 composed sandstone. The beds were formerly much quarried, and the 

 breccia being transported to Shrewsbury, and there subjected to heat, 

 a liquid bitumen was extracted, which, when prepared, was sold as a 

 medicine, under the name of " Betton's British Oil." Contiguous to 

 this quarry is a well, on the surface of which is a constant accumulation 

 of bitumen exuding from the adjoining strata. It will hereafter be 

 shown that where points of trap rocks penetrate the adjacent strata of 

 the Cambrian system there are frequently bituminous exudations near 

 the points of contact. 



" From the preceding details respecting the carboniferous deposits 

 near Shrewsbury, it appears, that the coal was formerly worked in those 

 spots only where it actually rose to the surface ; and that, even at the 

 present day, the speculation has not extended to any considerable dis- 

 tance beyond the mere outcrop. In the small irregular troughs at 



