J. R. Dakyns — Prof. Hull’s Carboniferous Classification. 313 
fresh water and marine : the other is tbe furtlier subdivision of tlie 
lower or marine portion into two bv uniting the Ganister Beds, 
Millstone Grit and Upper Limestone Shales into a Middle divisiou, 
and the Carboniferous Limestone and Lower Limestone Shales into 
a Lower division. 
It is difficult to see how the Lower Coal-measures and the Mill- 
stone Grit can properly be classed as essentialhj marine in the face of 
the coal-seams and beds of Ganister, which bespeak land-surfaces : 
but the proposal to unite the Lower Coal-measures or Ganister Beds 
with the Millstone Grit has soinething to recommend it, for the 
North of England at least, on stratigraphical grounds beyond the 
pakeoutological ones relied on by Prof. Hüll : for the two sets of 
beds have much in common ; workable coal-seams are not unknown 
in the Millstone Grit of Herbyshire, and such become more common 
as we go northward ; though the Sandstone Beds are as a rule coarser 
in the Millstone Grit than in the Lower Coal-measures, yet all 
Millstone Grits are not coarse ; some are very fine ; and grits quite 
as coarse as ordinary Millstone Grits do occasionally occur in the 
Lower Coal-measures. It is true we have a well-m’arked top to 
the Millstone Grit in Derbysliire and Yorkshire : but this I look 
upon as a happy accident : and were the Permian removed, where 
it hides the upper part of the Millstone Grit, perhaps we should find 
the Rougli Rock lose its well-marked character or possibly thin 
away altogether, and then where would our division-line be ? But, 
what is more important, beds of Ganister, which are the distinguish- 
ing feature of the Lower Coal-measures, occur also in the Millstone 
Grit : this is the case as far south as Derbysliire ; and as we go north 
the Ganister beds in the Millstone Grit become so prominent that the 
measures containing them might easily be mistaken for the equivalents 
of the Lower Coal-measures of South Yorkshire. 
Prof. Hüll furtlier proposes to dass the Upper Limestone Shales 
with the Millstone Grit. It has always beeil a difficult matter to 
separate these two subformations satisfactorily, except for quite 
limited areas. The line between the two has been drawn in very 
different places by different observers. The late Prof. Phillips 
drew the line below the great grit of Pendle Hill : subsequent ob- 
servers threw the equivalent of this grit, under the name of Yoredale 
Grit, into the Upper Limestone Shales. But Phillips was undoubt- 
edly right in classing it with the Millstone Grit ; for the grit in 
question is simply the basement bed of the Kinderscout Grit, from 
which it is offen quite impossible to separate it satisfactorily. The name 
Yoredale Grit, too, is a singularly unhappy one ; for it is more than 
doubtful whether any representative of this grit occurs in Yoredale 
at all. But in my opinion the term Yoredale, as a synonym for the 
old term Upper Limestone Shale, is itself incorrect. The type of 
beds developed in the vallev of the Yore is a very marked one ; also 
very peculiar, by no means generally characterizing the beds below 
the Millstone Grit ; it would seem better therefore to retain the old 
term Upper Limestone Shales for these measures generally, reserving 
the term Yoredale series for those cases in which the beds approxi- 
