74 



REPORT — 1877. 



upturned edges of the coal-seams been the source of the saline matter the water of 

 other coal-seams must have been similarly affected. Immediately above the Main 

 Coal, between it and the shale containing the marine shells, is a bed of impervious 

 clay called " Tow," and directly below it an equally compact bed of fire-clay ; and 

 it was the author's opinion that the saline water of the coal was in fact the fossil 

 or pent-up water of the sea in which those animals lived whose fossil remains had 

 been found in the shales above, and that it had been preserved to the present day 

 from evaporation and admixture by the impervious beds of clay, the position and 

 character of which he had described above. He adduced evidence he had met with 

 of the total submersion of every seam of coal found in the Ashby coal-field, and 

 in the other coal-fields of the Midlands, immediately after the completion of the 

 formation or deposition of each seam ; and from the fossils and other data therewith 

 associated, the submerging agent was, with few exceptions, fresh water; but 

 although there were several instances of the alternation of fresh- with salt-water 

 deposits in the Coal-measures generally, he knew of no other in which there was 

 so direct and clear an association of salt water with the fossil remains of marine 

 animals. The history of the Coal-formation of this county was as yet but imper- 

 fectly understood. 



The Carboniferous Limestone and Millstone Grit in the Country around 

 Llangollen, N. Wales. By George H. Morton, F.G.S. 



The author described the Carboniferous Limestone exposed in the Eglwyseg 

 ridge near Llangollen, N. Wales. He stated that the finest section is exposed at 

 the Ty-nant ravine on the west of Cefn-y-Fedw, and that the country around must 

 be considered as the typical area of the Lower Carboniferous series of North Wales. 

 The Millstone Grit, or Cefn-y-Fedw Sandstone, which reposes on the limestone in 

 the same district, was also described. The following tabulation explains the suc- 

 cession and thickness of the entire series : — 



Tabular view of the Carboniferous Limestone and Cefn-y-Fedw Sandstone in the 



country around Llangollen. 



Aqueduct Grit, or Upper Sandstone and ft.^; TT r, „ ^ , 



Conglomerate ... 70 I U Pf r ° fp^S* 



Upper Shale 80 f Dee-Bridge, or Mil 



Dee-Bridge Sandstone 30 J 



Lower Shale with Fire-clay and bands 



of limestone 18 



Middle Sandstone 200 



Cherty Shale 50 



Lower Sandstones and Conglomerate . . 2-">0 



Sandy Limestone 75^ 



f Upper Grey Limestone 300 T Upper Carboniferous 



Carboniferous J „ White „ 300 ( Limestone. 



Limestone. | Lower „ „ 120 1 



Cefn-y-Fedw 

 Sandstone. 



stone-Grit series. 



Middle and Lower 

 Cefn-y-Fedw or 

 Yoredale series. 



I 



Brown 



480 f 

 1923 



Lower ditto. 



Upper Old Red Sandstone 300 



Each of the subdivisions was separately described, and a section from the Ty-nant 

 ravine to Tyfyn-uchaf was exhibited, showing the regular succession of the whole 

 of the strata from the Old Red Sandstone to the Coal Measures. The following 

 Table shows the gradual attenuation of the Carboniferous Limestone towards the 

 south-east : — 



