CHAPTER XXII. 



Denudation of the Valley of the Weald, continued The alternative of the pro- 

 position that the chalk of the North and South Downs were once continuous, 

 considered Dr. Buckland on the Valley of Kingsclere Rise and denudation 

 of secondary rocks gradual Concomitant deposition of tertiary strata gradual 

 Composition of the latter such as would result from the wreck of the secon- 

 dary rocks Valleys and furrows on the chalk how caused Auvergne, the 

 Paris basin, and south-east of England one region of earthquakes during the 

 Eocene period Why the central parts of the London and Hampshire basins 

 rise nearly as high as the denudation of the Weald Effects of protruding 

 force counteracted by the levelling operations of water Thickness of masses 

 removed from the contra! ridge of the Weald Great escarpment of the chalk 

 having a direction north-east and south-west Curved and vertical strata in the 

 Isle of Wight These were convulsed after the deposition of the fresh-water 

 beds of Headen Hill Elevations of land posterior to the crag Why no Eocene 

 alluviums recognizable Concluding remarks on the intermittent operations of 

 earthquakes in the south-east of England, and the gradual formation of valleys 

 Recapitulation. 



Extent of denudation in the Valley of the Weald. ' IT would 

 be highly rash/ observes Mr. Conybeare, speaking of the denu- 

 dation of the Weald, ' to assume that the chalk at any period 

 actually covered the whole space in which the inferior strata 

 are now exposed, although the truncated form of its escarpment 

 evidently shows it to have once extended much farther than at 

 present *.' 



We believe that few geologists who have considered the 

 extent of country supposed to have been denuded, and who 

 have explored the hills and valleys of the central, or Forest 

 ridge, without being able to discover the slightest vestige of chalk 

 in the alluvium f, will fail to participate, at first, in the doubts 

 here expressed as to the original continuity of the upper secon- 

 dary formations over the anticlinal axis of the Weald. For our 

 own part, we never traversed the wide space which separates the 

 North and South Downs, without desiring to escape from the 

 conclusions advocated in the last chapter; and yet we have 

 * Outlines, p. 144, f See above, p. 295, 



