146 CARBONIFEROUS. 



CARBONIFEROUS. 



The term Carboniferous was applied by Conybeare in 1822 

 to that system of formations, intimately linked together, 

 which in our country include the great coal-producing rocks. 

 It is, however, chiefly in the upper portion or in the Coal- 

 measures proper that coal is worked. 



For reasons previously given the Upper Old Red Sand- 

 stone may now be grouped with the Carboniferous system. 

 Hence this division comprises the following formations : — 



Upper ( Coal Measures. 

 Carboniferous. ( Millstone Grit. 



rUpper Limestone Shales and Yore-^ -d ■ • 

 dale Rocks. ' Bernician 



Carboniferous or Mountain Lime- 

 Lower J stone. 

 Carboniferous. 1 Lower Limestone Shales and Tuedian 

 Beds. 

 Upper Old Red Sandstone and Basement Con- 

 '^ glomerate. (See p. 142.) 



and 



Calciferous 



Sandstone 



Series. 



When traced across England from Devonshire to Somerset- 

 shire and South Wales, and thence through Derbyshire to 

 Northumberland, very marked lithological changes take place 

 in the strata. We have much yet to learn about the 

 Carboniferous rocks of Devonshire, where they consist of grits 

 and shales, and but little limestone. The Lower Limestone 

 Shales do not form so distinct a group in the north (where 

 they are only locally represented), as they do on the Mendip 

 Hills and in South Wales. And in the northern areas it is 

 not easy to draw any separating line between the representa,- 

 tives of the Upper Old Red Sandstone or Basement beds of 

 the Carboniferous system, and the overlying Carboniferous 

 rocks. The Carboniferous Limestone of South Wales and 

 Somersetshire loses its marked calcareous character when 

 traced beyond Derbyshire, and becomes a series of limestones, 

 shales, and sandstones, with seams of coal in the far north ; 

 the Millstone Grit exhibits many modifications in different 

 localities ; the Yoredale Rocks, scarcely noticeable in the 

 South of England and in North Wales, attain great importance 

 in the North of England ; while the Coal-measures, perhaps 

 the most persistent type of the series, is at least a very 

 unprofitable member in Devonshire.^ 



1 See papers by Prof. E. Hull, Q. J. xviii. 137 ; xxiv. 319 ; xxxiii. 640. 



