587 
zontal and undisturbed upon the dislocated Carboniferous 
beds. This is proof that the anticlinals are earlier than the 
commencement of the Permian age. But the limits thus 
defined include a vast interval — a period greater than most 
of us would dare to assign to the whole history of our globe. 
During that blank in the geological record nearly all the 
Carboniferous Brachiopoda died out, animals whose low 
organisation implies great specific longevity. We must 
endeavour to establish a more precise date. It appears that 
part (perhaps nearly all) of the great interval between the 
close of the Carboniferous age and the commencement of the 
Permian was occupied by an enormous denudation of the 
coal-measures. This is known to have preceded the deposition 
of the lower Permian beds, from the fact that those deposits 
lie upon the denuded Carboniferous strata, and also from the 
occurrence of waterworn limestone and grit in Permian rocks. 
This denudation gives us another epoch. The Craven anti- 
clinals have been shewn to be later in their origin than the 
close of the Carboniferous period. Did they first appear 
before, during, or after the subsequent denudation ? We have 
reason for saying that they originated either altogether before 
the wasting of the Coal-measures, or before it had made con- 
siderable progress. The violent contortion of the beds must 
have been caused by lateral pressure resisted by the downward 
thrust of a great mass of superincumbent strata. Had the 
limestone been near the surface at the time of its elevation, 
we might have expected that the disturbing force would 
produce a mere fault, as it did in Nidderdale, where the 
superjacent strata were probably thinner. 
I have now finished my remarks upon what has been to me 
a very interesting portion of the Geology of Yorkshire. It 
is necessary to own great obligations to the writings of 
Professor Phillips. My labour will not have been misdirected 
if I have succeeded in collecting and rendering more intelli- 
