124 Dr. BucKLAND on the Formation of Valleys hy Elevation, 



having an opposite and outward dip from the axis of the valley, and thiSj often 

 at a high angle^ as near Fonthill and Barford in the vale of the Nadder^ and at 

 Oare near the base of Martinsell Hill in the Vale of Pewsey, obliges us to refer 

 their inclination to some antecedent violence,, analogous to that to which I have 

 attributed the position of the strata in the inclosed valleys nearKingsclere, Ham^ 

 and Burbage. Nor is it probable that without some pre-existing fracture or 

 opening in the lofty line of the great chalk-escarpment^ which is here pre- 

 sented to the north-west, the power of water alone would have forced open 

 three such deep valleys as those in question, without causing them to maintain 

 a more equable breadth, instead of narrowing till they end in a point in the 

 body of the chalk. 



A still larger and more decided example of the same kind of valley of eleva- 

 tion occurs in the well-known case of the great valley of the Weald of Kent 

 and Sussex ; surrounded as it is on all sides but the east by lofty escarpments of 

 chalk, facing towards each other with an outward dip in every direction, and 

 traversed from east to west by a central anticlinal line ; on either side of which 

 line the strata of iron-sand, weald-clay, lower green-sand, gault-clay, and fire- 

 stone sink like the two sides of a roof, with a high and regular inclination 

 beneath the inclosing escarpments of the chalk of the North- and South- 

 downs. The structure of this valley has been well represented in the sections 

 of Kent and Sussex published by Mr. W. Smith, and also in the section that 

 accompanies the inestimable work of Messrs. Conybeare and Phillips on the 

 Geology of England. This district has been usually described by the name of 

 the Kentish Denudation, seemingly from the hypothesis that the exposure of 

 all the strata here laid open, beneath the chalk, was the effect simply of denu- 

 dation. Now I am disposed fully to allow, that the force of water has been 

 sufficient to sweep away the greatest portion of the loose and shattered frag- 

 ments, which, after the elevation I am assuming, must have covered the axis of 

 this as well as the other valleys we have been considering, and which must 

 still have remained there in the form of rubbish, had there been no subsequent 

 diluvial action to drift them away : but I think the slightest inspection of the 

 sections I have referred to, will at once convince us, that no power of denuda- 

 tion by water could have produced the doubly inclined position of the entire 

 body of the strata within this district, as well as of the chalk by which it is 

 surrounded ; and that we must here again have recourse to a force producing 

 elevation from beneath, along the axis of the valley, if we would find an 

 adequate cause for the effects that have been produced in it along an extent of 

 60 miles in length and 20 miles in breadth. 



The facts then which we have examined, conspire to lead us to the conclu- 



