Carboniferous Limestone Series. By Hugh Miller. 117 



[ Upper Old Red Sandstone. Local conglomerates, ' more con- 

 nected with the Carboniferous than with the Devonian.' 

 No Stigmaria.~\ 



In 1875, Tate's classification of the upper divisions of the 

 series was set aside by Professor Lebour in favour of an arrange- 

 ment more ' natural and convenient.' Professor Lebour abolished 

 the distinction between the Calcareous and Carbonaceous groups, 

 and threw them, along with some of the Tuedian grits, 

 into a single large series, to which he applied the term 

 Bernician. This arrangement is . based on the assumption that 

 Tate's two divisions either do not exist in nature or do not persist 

 throughout the county. 



Carboniferous Limestone Series in Northumberland : 

 Lebour's Classification, 1875-1886. 



Bernician A large group — which ' cannot be divided 



in any natural manner ' — of limestones, 

 grits and sandstones, shales, and coals ; 

 lower limit, ' a variable one, ' not keeping 

 to any one horizon ; thickness, in North 

 Northumberland, 2,600 feet (after Tate) ; 

 in Mid Northumberland, a maximum of 

 ' at least 8,000 feet' (after Westgarth 

 Foster). 



Tuedian As in Tate's classification, but without 



definition at its upper limit. 



Basement Conglomerates Local. 



It has never been contended, the author believes, that Tate's 

 prior classification is not applicable to North Northumberland. 

 And it is now, as a result of the labours of the Geological Survey, 

 found to be equally applicable to South Northumberland, and 

 to the whole of what deserves to be distinguished as the North- 

 umbrian Type of the Carboniferous Limestone series, in contrast 

 with the Yorkshire type and Scottish type. 



The following table sets forth the classification as further 

 amplified and defined : — 



