CARBONIFEROUS LIMESTONE SERIES. I51 



Penton, north-east of Carlisle, have been described by Miss 

 Donald, of Stanwix. They include Aclisina costatula, Orihonema 

 quinquecarinata, etc' 



In Northumberland sandstones form a considerable part of the 

 series ; the limestones are for the most part inconstant, and like 

 cement-stones in character. In this district fossils are rare, but 

 obscure specimens of Nautilus and Athyris, together with Plant- 

 remains {Ulodendnm), have been noticed. Carter Fell, in the 

 Cheviot Hills, is in part made up of Tuedian Beds. (See p. 144.) 



Referring to the boundary between the Tuedian and Bernician 

 beds in Northumberland, Prof. Lebour observes that in places the 

 Harbottle grits, in the Upper Coquet, and the Great Dour grits, 

 form a lower line very distinct from the Tuedian purple shales and 

 cream-coloured beds upon which they rest. In other places there 

 is no distinct line of demarcation. Anodonta Jukesii h^?, been met 

 with in these passage-beds. On the flanks of the porphyritic mass 

 of the Cheviots, the Tuedian beds assume the red hue and coarse 

 structure which are characteristic of the Scottish Calciferous Series. 

 Prof. Lebour concludes that the divisional line between the Tuedian 

 and Bernician beds is one which in Northumberland separates 

 conditions of deposition rather than rigid horizons, and hence it 

 is a variable line.* 



Bernician Series. 



This term, derived from Bernicia, a Saxon kingdom occupying 

 what is now Berwickshire and much of the adjoining country, was 

 used by S. P. Woodward in 1856^ for the Lower Carboniferous 

 beds ; and the same name was independently suggested by Prof. 

 G. A. Lebour in 1875, for the representatives of the Carboniferous 

 Limestone and Yoredale rocks in those parts of the North of 

 England where no separating line can be drawn between them.* 

 As before mentioned, it is highly probable that the Tuedian Beds 

 (Calciferous Sandstone Series) represent a part of the Carboniferous 

 Limestone. Professor Phillips remarked, that in passing through 

 Northumberland these rocks become continually more and more 

 subdivided by interpolations of sandstone, shale, and coal, till on 

 the sea-coast, north of Belford, a part of this series contains a 

 number of bands of limestone, separated by many times their 

 thickness of sandstone and shale, and under the whole lie workable 

 seams of coal. The character of the surface of the western and 

 north-western part of Northumberland corresponds to this change 

 of the component strata. Instead of the beautiful green pastures 



^ Trans. Cumberland Assoc. 1885, p. 127. 



^ Proc. N. of England Inst. Mining Engineers, vol. xxv. ; Geology of 

 Northumberland, p. 45. See also W. Gunn, G. Mag. 1885, p. 93 ; and Prof. J. 

 Geikie, Trans. Inst. Engineers, Scotland, 1871. 



^ Manual of Mollusca, p. 409. 



* G. Mag. 1875, p. 543 ; 1877, p. 19. 



