TJIE CARBONIFEROUS 8YSTKM 265 



Bernician Series. On the southern border of Northumber- 

 land the Scar limestone of Yorkshire and the Yoredale Beds are 

 still distinguishable as separate stages, but as they are followed 

 northward they lose their distinctive characters and merge into one 

 great series of alternating limestones, shales, and sandstones, with 

 many workable beds of coal. 



The most remarkable feature of this series is the great develop- 

 ment of mechanical sediments in the centre of the county, some of 

 the lower beds expanding into the " Carbonaceous " Group, and 

 many fresh beds of sandstone and shale with coal-seams coming in 

 above the Main Yoredale limestone to form the upper calcareous 

 division, so that the whole is about 6000 feet thick, but again 

 ! .twines thinner to the northward. 



The Carbonaceous division has not yielded many marine fossils, 

 but Professor Garwood has found Spiriferina laminosa with 

 dendroid Lithostrotions, and the group is referable to D r The lower 

 calcareous group contains species of Dibunophyllum with Cyatho- 

 phyllum regium and Lithostrotion junceum, so that its zonal age is 

 evident, and it is noteworthy that several of the limestones are 

 largely composed of the Foramtnifer Saccammina Carteri. 



The Oxford limestone is probably the equivalent of the Hardraw 

 limestone of Durham, and if so the beds above this correspond 

 with the Yoredale Group, but the Pendleside Cephalopoda have not 

 yet been found. On the other hand, the corals Lonsdaleia 

 floriformis and Alveolites septotsa, with the Brachiopods Productus 

 giganteus and P. Intissimus, first appear in and above the Oxford 

 limestone. 



6. Scotland 



The central lowknds of Scotland display a great thickness of 

 Lower Carboniferous rocks which may be regarded as the equivalents 

 of the Tuedian and Bernician Series of Northumberland, for the 

 Scottish Series is similarly divisible into a lower group, which is 

 mainly arenaceous, and an upper more varied group of shales, 

 sandstones, limestones, and coals. The lower has been called the 

 Calciferous Sandstone Series, and the upper was termed the 

 Carboniferous Limestone Series, but the equivalents of the main 

 mass of the Carboniferous limestone lie entirely below this " lime- 

 stone series " of Scotland. Thus the nomenclature formerly used 

 by the Geological Survey and adopted in most text-books gives 

 rise to misconception and tends to exaggerate the stratigraphical 

 importance of the upper part of the series. For while the upper 

 portion, which has a thickness of only from 1600 to 1800 feet, 



