﻿Vol. 64.] ANNIVEESAEY ADDKESS OF THE PRESIDENT. Cxix 



Weald was suddenly upheaved, and that as a consequence of 

 this disturbance a series of longitudinal folds was formed, with 

 transverse fissures at right angles to them. He looked upon the 

 transverse valleys as marking the lines of the faults by which they 

 had been determined. Subsequent detailed examination of the 

 ground has failed to reveal these theoretical faults, and though 

 perhaps traces of some of them may ultimately be detected, there can 

 hardly be any doubt that, as a whole, the valleys have been carved 

 out independently of any dislocations. Hopkins's explanation of 

 the topography of the Weald was based on a detailed mathematical 

 discussion of the action of the underground forces by which the 

 elevation of the great Wealden anticline was supposed to have 

 been effected. But, in spite of its imposing mathematical basis, 

 the data which it assumed did not agree with the actual facts as 

 since ascertained, and its resulting conclusions were not less 

 erroneous than other speculations on the subject.^ 



It was not until the summer of 1862 that in this country the 

 subject of the origin of valleys was taken up in serious earnest, 

 and worked out on the ground in definite reference to a group 

 of actual rivers. On the 18th of June in that year J. B. Jukes 

 read to the Society his memorable essay ' On the Mode of Formation 

 of some of the River- Valleys in the South of Ireland.' I can well 

 remember the vivid impression made on my own mind by the 

 appearance of this paper in the Quarterly Journal. It threw 

 a flood of fresh light on the whole question, suggested new ways 

 of approaching the subject, and confirmed views which one had 

 long been tentatively adopting. There can, I think, be no doubt 

 that it was this essay that started the vigorous study of the origins 

 of landscape, which has been so characteristic a feature in the 

 geological activity of the last forty years. Here, again, is a 

 conspicuous instance of the impulse given to the development of 

 geological research by papers published by this Society. 



It would lead me far beyond the limits which I have traced for 

 myself in this Address to attempt to give here any sketch of the 

 subsequent progress of the enquiries initiated by Jukes. A large 

 part of the considerable mass of literature which has been devoted 

 to the subject has been published in various forms outside of this 



^ It may be mentioned here that the natural presumption, that the transverse 

 yalleys by which the surrounding Ohalk-escarpments of the Wealden area 

 were breached had their lines determined by faults, was held long before. 

 See, for instance, Scrope, ' Considerations on Volcanoes' 1825, p. 214. 



