CHAPTEK XVII. 



THE CARBONIFEROUS GROUP. 



Coal-measures of English ; Terrain Houiller of French ; Kohlen-Gebilde of 

 German Authors. 



MUSEUMS : British Museum, Geological Society, those of Newcastle, Dudley, 

 Leeds, Halifax, Edinburgh, Glasgow, Dublin, and the Cabinets of many 

 Private Collectors. 



AUTHORS : Buckland, Lindley and Hutton, Artis, Witham, Phillips, Martin, 

 Farey, Brongniart, Sternberg, Presl, Cotta, Corda, Knorr, Schlotheim. 



CHARACTERISTICS : A vast group, composed of alternations of Marine and 

 Freshwater Strata, beds of Ironstone and Coal, with Shales and Grits, 

 remarkable for the abundance and variety of their Fossil Plants. 



have so often had occasion to allude to the coal forma- 

 tion, that a mere outline of its principal and characteristic 

 features will suffice for the present description, and for 

 more ample details we must refer to the various works of 

 the authors above quoted, which treat at length of this 

 highly interesting and important group. 



The coal-fields of the British islands are extremely 

 numerous, and the distribution of the beds varies according 

 to local circumstances. The following will, however, be 

 found to afford a general outline of their disposition and 

 arrangement. 



Coal-measures. 



Strata of shale, sandstone, and grit, with occasional seams 

 of coal and layers of ironstone. 



Millstone grit. 



A coarse quartzose sandstone, passing into a conglomerate, 

 sometimes used for millstones. 



Carboniferous limestone, or mountain limestone; a cal- 

 careous rock, containing marine shells and corals. 



The following table, by Professor Phillips, shows the com- 



