454 Notices of Memoirs — British Association — 



in the Lake District, but tlirougbout the north-west of England 

 generally. But while it is doubtful whether any of the physical 

 features then produced have survived, it seems to be beyond dispute 

 that it was in consequence of the pre-Permian movements that the 

 older rocks of the Lake District were freed from their Carboniferous 

 covering, and that to this extent the district may be said to have 

 been blocked out in pre-Permian times. The detailed sculpturing 

 resulted from later movements, with which we are not now concerned. 



During this same period there rose into relief that jjart of the 

 Pennine axis which runs between Lancashire and Yorkshire. The 

 doming up of the Lower Carboniferous rocks and the wildness of 

 the moorlands which characterise their outcrops have impressed 

 all who have had occasion to cross from the one populous coalfield 

 to the other, and have gained the name of the ' backbone of England ' 

 for this anticlinal axis. Whether, however, it can be regarded as 

 one axis or as the result of several movements is doubtful, but 

 not material for our present purpose. Regarded as a geological 

 structure it is not continuous with that part of the Pennine axis 

 which runs along the north-eastern frontier of the Lake District. 



Passing westwards from the Pennine axis, we cross the deep and 

 broad Triassic basin of Cheshire, which may be regarded as the 

 complement of the dome of elevation of Derbyshire. To the west 

 of this, again, we reach a part of North Wales which was more or 

 less shaped out by the earth-movements which came into action 

 between the Carboniferous and Permian periods. Two leading 

 faults traverse the district. The one runs in a north-north-westerly 

 direction across Denbighshire and introduces that little bit of 

 "Cheshire in Wales" known as the Vale of Clwyd. Though there 

 has been some later movement along this fault, it was in the main 

 pre-Triassic, which statement, in view of the perfect conformity 

 between the Permian and Trias, amounts to saying that it was 

 pre-Permian. The other passes across Wales in a north-easterly 

 direction along the Dee Valley at Bala, and reaches the Triassic 

 basin between Chester and Wrexham. The date of this fault has 

 not been worked out in detail, but the fact that it is associated 

 with a pre-Triassic anticline, where it reaches the Triassic margin, 

 proves that it is in part at least of pre-Triassic age. In Anglesey 

 also there has been strong post-Caboniferous folding in the same 

 north-east to south-west direction. 



It is to be noticed, further, that the Carboniferous rocks maintain 

 their characters to their margins on the flanks of the Clwydian Hills 

 and other ranges of Silurian rocks in North Wales. Both along the 

 coast, and even in a little outlier preserved near Corwen by an 

 accident of faulting, they show a persistence of type and of detail 

 in sequence which could hardly have been maintained had the 

 Silurian uplands existed in Carboniferous times. The inference 

 that the uplands of Denbighshire and Flintshire are the result of 

 post-Carboniferous upheaval is strengthened by the fact that the 

 Carboniferous rocks reposing on their flanks are tilted at an angle 

 which would carry them over their tops. This part of North Wales, 



