Lxxvi PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



zoiital or slightly inclined surfaces of the magnesian conglomerate 

 at Kirby Stephen and Bela bridge, as well as at Westhouses near 

 Ingleton, lead to the conclusion that these faults were anterior to the 

 magnesian rocks. The only objection to this conclusion is derived 

 from a limited dislocation of the conglomerate near Brough, where 

 however it is not in conformity of disturbance with the carboniferous 

 limestone. Upon the whole then I venture to adopt the conclusion, 

 that the Penine and Craven faults, as well as the Ribblesdale and 

 Derbyshire disturbances, preceded the Magnesian Limestone epoch, 

 b'jt the Tjaiedale fault and some other considerable dislocations are of 

 somewhat later date. It is however impossible to close the discussion 

 without expressing the surprise I feel, that such a complicated pro- 

 blem as that of the age of a great system of convulsions should evep 

 be thought easy of solution." 



I would remark on the above extract, that, supposing, with the 

 author, the great faults bounding this district on the west to have been 

 anterior to the Magnesian Limestone, it would seem extremely impro- 

 bable that they should have been anterior also to the first movement 

 which broke up the Coal-measures ; for, in such case, these enormous 

 dislocations would be unconnected with any great movement in the 

 surrounding district, — a conclusion which, to any geologist acquainted 

 with them, must I conceive appear incredible. I make this remark in 

 consequence of the date which, as we shall see hereafter, M. de Beau- 

 mont assigns to the elevation of Cross Fell. The Ashby de la Zouchcoal, 

 on the borders of Charnwood Forest, is ovei'laid unconformably by 

 Triassic beds, as is likewise, I believe, the neighbouring field of War- 

 wickshire. In both cases the strikes are parallel to the central axis 

 of Charnwood Forest, about 30° W. of N . In the Ashby de la Zouch 

 field the Magnesian Limestone is wanting. 



In the Dudley coal-field the Permian beds are developed in great 

 thickness, but without any distinct bed of Magnesian Limestone. 

 Sir E. Murchison states that its lowest portion rests conformably on 

 the coal strata, and has been elevated with them. The geologists of 

 the Survey, however, have recognized distinct indications of discon- 

 tinuity between these formations, but still of that amount only which 

 would not be detected by examination of the surface of junction in 

 any one limited locality. Thus, whether we allow this discontinuity 

 or not, we may still assert that no great dislocating movement can 

 have taken place in this district before the middle of the Permian 

 period. Another must have taken place before the conclusion of the 

 Triassic period, for beds of that period in the northern part of this 

 field repose unconformably on the beds of coal. It is probable, however, 

 that the great dislocating movement here took place after the Triassic 

 period. The coal district is bounded on the east and west by great 

 faults which are continuous from one end of it to the other, that on 

 the western side having been traced, moreover, into the New Red 

 Sandstone to the north, and many miles to the southward into the 

 Lias, where it dies away. It dislocates this latter formation, and 

 must therefore have been posterior to it, at least in its southern 

 portion. Along the boundaries of the field itself, it dislocates the 



