l62 CARBONIFEROUS. 



area of Coal-measures is not without its parallel elsewhere in 

 England. There are patches of Limestone situated in the Coal- 

 tract of Clapton-in-Gordano, near Bristol ; and near Chudleigh, in 

 Devonshire, in the midst of the Culm-measures, there are some 

 very puzzling masses of Devonian Limestone. (See p. 131.) 

 Were a geologist, indeed, whose mind was filled with Glacial 

 theories, to come directly from Norfolk or Lincolnshire, having 

 been impressed with the really wonderful transported masses of 

 Chalk met with in the Drift of the one county, or of Inferior 

 Oolite and Marlstone that are occasionally met with in the other, 

 he might be led to suggest a similar explanation to account for the 

 isolated masses of Limestone that occur on the Coal-measures of 

 Somersetshire. But, after all, the question is not which agent is 

 most capable of producing the phenomena, but which agent 

 capable of the work is most in accordance with facts. 



A very detailed section of the Carboniferous Limestone at 

 Clifton, near Bristol, and indeed of the whole of the beds between 

 the Millstone Grit and Old Red Sandstone, was made many years 

 ago by Mr. D. H. Williams, The Carboniferous Limestone is dark 

 grey and reddish in colour ; partially divided by shales ; in 

 places compact or oolitic, shelly and crinoidal. It is about 1500 

 feet in thickness. The lower beds, comprising Encrinite- and Fish- 

 beds, are worked in the Black Rock Quarry. Above come other 

 beds characterized by various fossils, Lithostrotion aranea, Prodiidiis 

 longispinus, Euomphalus nodosus, Bdlcrophon apetius, Cyclophylliim 

 fiingitcs, Chatdes radians, etc.^ (See Fig. 26.) Fossils may also be 

 obtained at Portishead, Henbury, Clevedon, Weston-super-Mare, etc. 



At Cannington Park, near Bridgewater, there is a mass of lime- 

 stone, much disturbed, which has by different geologists been 

 classed as Devonian or Carboniferous : it resembles both in litho- 

 logical character, but is no doubt of Carboniferous age, on account 

 of the fossils collected by Mr. W. Baker, Mr. J. D. Pring, Mr. E. 

 B. Tawney, and others. These fossils include Lithostrotmi irregn- 

 lare, Clissiophyllum turbinatum, etc.^ 



At the base of the Culm-measures in Devonshire are impersistent 

 beds of black limestone, which probably represent portions of the 

 Carboniferous Limestone. As these beds are intimately connected 

 with the Culm-measures above, it will be most convenient to 

 describe them together. (See sequel.) 



Econojnic products, etc. 



The Carboniferous Limestone is extensively burnt for lime. It is also largely 

 used for road-mending, for which purpose it is conveyed to great distances. The 

 stone quarried in the Mendip Hills is advertised as " Mendip Granite" ! From 

 its hardness it is not serviceable as a freestone, but it is locally used for building 



^ De la Beche, Mem. Geol. Survey, i. 113; W. W. Stoddart, Proc. Bristol 

 Nat. Soc. (2), i. 322 ; and Proc. Cotteswold Club, vii. 144 (plate). 



- See S. G. Perceval, G. Mag. 1872, p. 94 ; Tawney, Proc. Bristol Nat. Soc. 

 ser. 2, vol. i. p. 380 ; Champernowne and Ussher, Q. J. xxxv. 547. 



