Stratification of the Limestone District of Derbyshire. 125 



faults has suffered, while on either side of the valley, beyond 

 the faults, we find such undoubted indications of immense dis- 

 locations. 



The formation of this curious and beautiful vale, cutting 

 completely through the elevated central ridge of the district, 

 perpendicularly to its direction, is thus simply accounted for. 

 I have entered with some detail into the explanation of it tor 

 the purpose of comparing it with the necessary deductions 

 from Farey's view of the subject. He asserts, as I have be- 

 fore mentioned, that the basset of the second toadstone crosses 

 the Wye at the mouth of Crossbrook Dale*, in which case 

 the limestone forming the N. side of Monsal Dale, imme- 

 diately E. of this point, must be the second, and as such 

 Farey has in fact described it. But this limestone is seen in 

 Crossbrook Dale, at the fault about 300 or 400 yards from 

 the Wye, to abut directly against his first toadstone, as above 

 described. Hence we must conclude that the limestone 

 on the south side of this fault (instead of that on the north 

 side, as I conceive,) has been elevated, and to an immense 

 height, since the first limestone and first toadstone are no 

 longer superincumbent upon it. And yet it is in this mass of 

 limestone thus elevated above the adjoining part, accord- 

 ing to Farey, that the present deep valley of the Wye has 

 been excavated. How the river first selected such a course 

 is most marvellous. The explanation I have myself given of 

 the formation of this valley will at least appear to have the 

 testimony of hydrostatical principles in its favour. 



It is almost incredible that so industrious an observer as 

 Farey must have been, should have failed to note any one of 

 the longitudinal faults in the district bordering the Wye, 

 though they are so frequent and characteristic, following al- 

 most to mathematical accuracy the law of parallelism. We 

 might suppose from his account of this interesting tract that 

 the stratified masses which it comprises remain, relatively at 

 least to each other, in the regular and undisturbed order in 

 which they were first deposited, although in its external cha- 

 racters we cannot fail to mark the most obvious indications of 

 violent dislocation. This is not, however, the only instance 



* A patch of toadstone which is seen at this point at the level of the 

 Wye has, no doubt, led to this erroneous notion. It must not be con- 

 founded with that before mentioned in the southern part of Crossbrook 

 Dale as belonging, according to Farey, to his first bed. According to my 

 own view of the subject it belongs to the undisturbed portion of limestone 

 and toadstone lying between the two parallel faults described above. 

 Other patches show themselves at several places along the valley, indi- 

 cating that this undisturbed portion of the toadstone lies just beneath the 

 bed of the river. 



